FAQs

MVHR (Mechanical Ventilation with Heat Recovery) is a whole-house ventilation system that provides a continuous supply of fresh, filtered air while removing stale, moisture-laden air from the home.

The system works by extracting warm air from rooms that generate moisture and odours, such as kitchens, bathrooms and utility rooms. At the same time, it supplies fresh air to living rooms, bedrooms and other habitable spaces. Before the extracted air is discharged outside, it passes through a heat exchanger where most of its heat is transferred to the incoming fresh air without the two air streams mixing.

This heat recovery process allows the home to remain well ventilated while reducing the amount of heat that would otherwise be lost through traditional ventilation methods. The result is a healthier indoor environment with fresh, filtered air, improved comfort and greater energy efficiency.

MVHR systems operate continuously at a low level to maintain good indoor air quality and can automatically increase airflow when higher levels of moisture are detected from activities such as showering, cooking or drying clothes.

By combining effective ventilation with heat recovery, MVHR helps reduce condensation, control humidity, improve indoor air quality and create a more comfortable living environment throughout the year.

No, a properly designed, installed and commissioned MVHR system should operate very quietly and, in most cases, you will hardly notice it is running.

Modern MVHR units use energy-efficient, low-noise fans and are designed to provide continuous ventilation at low airflow rates. When correctly sized for the property and balanced during commissioning, the system should deliver fresh air without creating noticeable noise in living spaces or bedrooms.

The ductwork design also plays an important role in noise levels. Correct duct sizing, routing and airflow settings help minimise air resistance and prevent unwanted noise from air movement through the system.

In many homes, the noise generated by an MVHR system is significantly lower than the external noise that enters through open windows. As a result, homeowners often find that MVHR helps create a quieter and more comfortable indoor environment while still providing a constant supply of fresh air.

If an MVHR system is producing excessive noise, this can sometimes indicate a maintenance issue, blocked filters or that the system has not been correctly commissioned. Regular maintenance and filter cleaning will help ensure the system continues to operate efficiently and quietly.

When professionally designed and installed, most homeowners find that their MVHR system quickly fades into the background, providing fresh, filtered air with minimal noise or disruption.

Yes, like any ventilation system, an MVHR system requires regular maintenance to ensure it continues to operate efficiently and provide good indoor air quality.

The good news is that routine maintenance is simple and can usually be carried out by the homeowner. To keep the system performing at its best, the internal extract valve filters should be cleaned every three months. These filters help capture dust and debris before they enter the ductwork and can be easily removed and cleaned.

The filters within the MVHR unit itself should be cleaned every six months. Regular cleaning helps maintain airflow, protects the system components and ensures the unit continues to operate efficiently.

For homeowners who have chosen an optional pollen filter, this should be replaced every six months. Unlike standard filters, pollen filters are designed to capture finer particles and allergens, and replacement is recommended to maintain their effectiveness.

Regular maintenance helps ensure the system continues to deliver fresh, filtered air throughout the home while reducing energy consumption and maintaining optimal performance. Neglecting filter maintenance can restrict airflow, reduce efficiency and impact indoor air quality.

By following the recommended maintenance schedule, homeowners can enjoy reliable, efficient ventilation and help extend the lifespan of their MVHR system.

Yes, a properly designed, installed and commissioned MVHR system can fully comply with UK Building Regulations.

MVHR systems are commonly used in new-build homes and renovation projects to meet the ventilation requirements set out in Approved Document F (Ventilation). As modern homes become more airtight and energy efficient, effective ventilation is essential to maintain good indoor air quality and remove excess moisture from the property.

To comply with Building Regulations, an MVHR system must be correctly sized for the property, provide the required airflow rates and be professionally commissioned to ensure it performs as designed. Commissioning includes measuring and balancing the airflow throughout the home and providing the relevant documentation for Building Control where required.

MVHR can also contribute to compliance with Approved Document L (Conservation of Fuel and Power) by reducing heat loss through ventilation. By recovering heat from the extracted air and using it to temper incoming fresh air, MVHR helps improve the overall energy efficiency of the home.

It is important to note that simply installing an MVHR system does not automatically guarantee compliance. Proper system design, installation and commissioning are all essential to ensure the ventilation requirements of the property are met.

When correctly specified and commissioned, MVHR provides an effective way to achieve Building Regulations compliance while delivering the additional benefits of fresh air, improved indoor air quality and energy-efficient ventilation.

An MVHR (Mechanical Ventilation with Heat Recovery) system continuously extracts stale air from your home while supplying fresh filtered air. It recovers heat from outgoing air and transfers it to incoming air, improving air quality and energy efficiency.

If you are still experiencing condensation despite having an MVHR system installed, it usually indicates that there is an underlying issue affecting the performance of the system or that excess moisture is being generated within the home.

One of the first things to check is whether the filters are clean. Dirty filters can restrict airflow and reduce the system's ability to remove moisture from the property. We recommend cleaning the internal extract valve filters every three months and the unit filters every six months. If your system is fitted with an optional pollen filter, it should be replaced every six months.

Condensation can also occur if the MVHR system has not been commissioned correctly or if the airflow settings have been altered. An unbalanced system may not be extracting enough moisture-laden air from bathrooms, kitchens or utility rooms, allowing humidity levels to build up.

In some cases, the amount of moisture being generated within the home may exceed the system's normal ventilation rate. Activities such as drying clothes indoors, long showers, cooking without using boost mode or high occupancy levels can all contribute to increased humidity.

It is also important to remember that not all condensation and damp problems are caused by poor ventilation. Issues such as water leaks, penetrating damp, rising damp, inadequate insulation or cold bridges can all result in condensation-like symptoms that an MVHR system alone cannot resolve.

If your filters are clean, the system is running correctly and condensation is still present, we recommend contacting our team for advice. We can help determine whether the issue is related to system performance, commissioning or another building-related problem.

A properly maintained and commissioned MVHR system should significantly reduce condensation by continuously removing excess moisture and supplying fresh, filtered air throughout the home.

Yes, MVHR can be installed in many existing homes, not just new-build properties.

While MVHR systems are often associated with modern, airtight homes, they can also provide significant benefits in older properties, particularly where homeowners experience issues such as condensation, damp, mould, poor ventilation or stale indoor air.

The suitability of an existing property will depend on factors such as the available space for ductwork, the layout of the home and the overall condition of the building. In some cases, minor alterations may be required to accommodate the ducting and ventilation unit, but a well-designed system can often be installed with minimal disruption.

For existing homes, the primary benefits of MVHR are typically improved indoor air quality, better control of humidity and condensation, and a healthier, more comfortable living environment. Homes that have undergone insulation upgrades or improvements to airtightness can also benefit from the heat recovery and energy-saving advantages that MVHR provides.

Every property is different, which is why a professional assessment is recommended to determine the most suitable MVHR solution. With the right design and installation, many existing homes can successfully enjoy the benefits of whole-house heat recovery ventilation.

No, MVHR is not only suitable for new-build properties.

Although MVHR is commonly installed in new-build homes because they are typically more airtight and energy efficient, many existing properties can also benefit from a well-designed MVHR system. In fact, homeowners often choose MVHR to address issues such as condensation, mould, poor indoor air quality and inadequate ventilation in older homes.

Modern MVHR systems can be installed in a wide range of property types, including detached houses, semi-detached homes, bungalows, apartments and renovation projects. The key consideration is whether there is a practical route for the ductwork and sufficient space for the ventilation unit.

While heat recovery efficiency is generally greatest in well-insulated and airtight homes, existing properties can still benefit from the continuous supply of fresh, filtered air and the removal of stale, moisture-laden air. This can help create a healthier and more comfortable indoor environment while reducing the risk of condensation and damp-related problems.

Every property is different, which is why professional system design is important. A site survey can assess the layout of the home and identify the most effective MVHR solution for the building and its occupants.

MVHR recovers heat using a highly efficient component called a heat exchanger.

As warm, stale air is extracted from areas such as kitchens, bathrooms and utility rooms, it passes through the heat exchanger before being discharged outside. At the same time, fresh air is drawn into the system from outdoors and passes through the opposite side of the heat exchanger.

The heat exchanger transfers thermal energy from the outgoing air to the incoming fresh air without the two air streams mixing. This means the fresh air is pre-warmed before it enters the home, reducing the amount of energy needed to maintain comfortable indoor temperatures.

Modern MVHR systems can recover a significant proportion of the heat that would otherwise be lost through ventilation, making them far more energy efficient than traditional extract fans or opening windows for ventilation.

By recovering heat while continuously supplying fresh air, MVHR systems help improve comfort, reduce heat loss and maintain healthy indoor air quality throughout the year. This makes them particularly beneficial in modern, energy-efficient homes, although many existing properties can also benefit from the improved ventilation and heat recovery they provide.

The maintenance schedule for MVHR filters depends on the type of filter and its location within the system.

For our systems, the internal extract valve filters should be cleaned every three months. These filters help prevent dust and debris from entering the ductwork and can be easily removed and cleaned as part of routine maintenance.

The filters within the MVHR unit should be cleaned every six months to maintain good airflow and ensure the system continues to operate efficiently.

If your system is fitted with an optional pollen filter, this should be replaced every six months. Pollen filters are designed to capture finer particles and allergens, and regular replacement is important to maintain their effectiveness and indoor air quality benefits.

Keeping filters clean is one of the most important aspects of MVHR maintenance. Dirty or blocked filters can restrict airflow, reduce heat recovery efficiency and impact the overall performance of the system.

Following the recommended maintenance schedule will help ensure your MVHR system continues to provide fresh, filtered air and efficient ventilation throughout your home.

For many homes, both new and existing, MVHR (Mechanical Ventilation with Heat Recovery) is a worthwhile investment. It provides a continuous supply of fresh, filtered air while extracting stale, moisture-laden air from kitchens, bathrooms and utility rooms. This helps create a healthier, more comfortable indoor environment and can significantly reduce issues such as condensation, damp and mould.

In modern airtight homes, MVHR is particularly effective because it recovers heat from the extracted air and uses it to warm incoming fresh air, helping to reduce heat loss and improve energy efficiency. However, MVHR can also be highly beneficial in older properties. Even where airtightness levels are lower, it provides consistent whole-house ventilation that improves air quality, controls excess moisture and reduces reliance on opening windows, especially during colder months.

While the energy-saving benefits are greatest in well-insulated, airtight homes, existing properties can still benefit from improved comfort, healthier indoor air and better moisture control. For homeowners struggling with condensation, poor ventilation or stale air, MVHR is often one of the most effective long-term solutions available.

No, a properly designed and commissioned MVHR system should not make a room feel draughty.

Unlike opening a window, which can allow large volumes of cold air to enter a room, an MVHR system supplies fresh air at carefully controlled airflow rates. The incoming air is also tempered through the heat recovery process, meaning it enters the home closer to the indoor temperature rather than at the outdoor temperature.

Supply valves are positioned and adjusted to distribute air gently and evenly throughout the room, helping to avoid uncomfortable air movement. When the system is correctly balanced, most homeowners are unaware of the airflow and simply notice that the home feels fresher and more comfortable.

In fact, many people find that MVHR improves comfort by eliminating cold draughts associated with trickle vents, extractor fans and regularly opening windows for ventilation.

If a room does feel draughty, this may indicate that the airflow settings need adjusting or that the system has not been commissioned correctly. A properly designed MVHR system should provide continuous fresh air without creating noticeable draughts or discomfort.

By delivering fresh, filtered air in a controlled manner, MVHR helps maintain a comfortable indoor environment while reducing heat loss and improving indoor air quality.

A properly designed, installed and commissioned MVHR system should operate very quietly. If you are noticing excessive noise, there are several possible causes that may need attention.

One of the most common reasons is dirty or blocked filters. As filters become clogged, the system may have to work harder to maintain airflow, which can increase fan noise and air movement sounds. Regular maintenance helps prevent this and keeps the system operating efficiently.

Noise can also occur if the system has not been commissioned correctly or if airflow settings have been altered. Excessive airflow rates can create noise at the valves, within the ductwork or at the MVHR unit itself. A professionally balanced system should deliver the required ventilation rates without creating noticeable noise.

In some cases, rattling or vibration noises may indicate loose ductwork, fixings or components. These issues are often straightforward to resolve but should be investigated to prevent further problems.

If the noise is coming directly from the unit, it may be related to worn components, a fan issue or a fault that requires inspection. Any fault symbols displayed on the controller should also be checked, as they may help identify the cause.

Start by ensuring the filters are clean and that there are no obstructions around the vents. If the noise persists, we recommend contacting our team for advice and further investigation.

A well-maintained and correctly commissioned MVHR system should provide fresh, filtered air with minimal noise, allowing it to blend into the background of everyday life.

No, MVHR is not specifically required under UK Building Regulations. However, all homes must have adequate ventilation to comply with the requirements of Approved Document F (Ventilation).

Building Regulations set out the ventilation performance that a property must achieve, but they do not usually dictate the type of ventilation system that must be installed. There are several ways to meet these requirements, including intermittent extract fans, continuous mechanical extract ventilation (MEV) and Mechanical Ventilation with Heat Recovery (MVHR).

MVHR is often chosen for modern new-build homes and energy-efficient properties because it provides continuous ventilation while recovering heat that would otherwise be lost. This makes it an effective solution for meeting ventilation requirements while supporting the property's overall energy efficiency.

As homes become increasingly airtight, achieving the required ventilation rates through natural ventilation alone can become more challenging. In these situations, MVHR is often considered one of the most effective and practical solutions for maintaining good indoor air quality and complying with Building Regulations.

Whether MVHR is the right choice for your project will depend on factors such as the property's design, airtightness and energy performance targets. While it is not a mandatory requirement, it is widely regarded as one of the best ventilation solutions available for modern homes.

Approved Document F is the section of the Building Regulations for England that sets out the requirements for ventilation in residential buildings.

Its purpose is to ensure that homes receive sufficient fresh air and that stale, moisture-laden air is effectively removed. Proper ventilation is essential for maintaining good indoor air quality, reducing the risk of condensation and mould, and creating a healthy living environment for occupants.

Approved Document F specifies the minimum ventilation rates that a property must achieve, along with guidance on the different types of ventilation systems that can be used. These include natural ventilation, intermittent extract fans, continuous mechanical extract ventilation (MEV) and Mechanical Ventilation with Heat Recovery (MVHR).

As modern homes become more airtight and energy efficient, achieving adequate ventilation has become increasingly important. MVHR is a popular solution because it provides the required ventilation while recovering heat that would otherwise be lost, helping to improve both indoor air quality and energy efficiency.

To comply with Approved Document F, a ventilation system must be correctly designed, installed and commissioned. This includes ensuring the required airflow rates are achieved and providing commissioning data where necessary for Building Control approval.

In simple terms, Approved Document F sets the standards that ensure homes are properly ventilated, helping to create healthier, more comfortable living environments.

MVHR systems are suitable for a wide range of properties, including new-build homes, self-build projects, renovated properties and many existing homes. They are particularly effective in well-insulated and airtight buildings, where they can maximise heat recovery and energy efficiency.

However, MVHR is not limited to modern homes. Many older properties can also benefit from continuous fresh air, improved indoor air quality and better control of condensation and damp. A professionally designed system can help address common issues such as mould growth, stuffy rooms and excess humidity, while providing a consistent and comfortable indoor environment.

Whether you're building a new home, carrying out a major renovation or looking to improve ventilation in an existing property, an MVHR system can often be tailored to suit your home's layout and requirements. The best way to determine suitability is through a professional assessment of the property and its ventilation needs.

Yes, replacing and cleaning MVHR filters is a simple task that can usually be carried out by the homeowner without the need for specialist tools or technical knowledge.

As part of routine maintenance, the internal extract valve filters should be cleaned every three months, while the filters within the MVHR unit should be cleaned every six months. If your system is fitted with an optional pollen filter, this should be replaced every six months to maintain its effectiveness.

Most filters can be accessed quickly and easily by following the manufacturer's instructions. Regular filter maintenance helps ensure the system continues to provide good airflow, efficient heat recovery and high indoor air quality.

Keeping on top of filter maintenance can also help reduce energy consumption, prevent unnecessary strain on the system and extend the lifespan of the MVHR unit.

If you are unsure which filters your system uses or how to access them, our team is always happy to provide guidance and help you source the correct replacement filters.

MVHR helps reduce condensation by continuously removing excess moisture from the air before it has a chance to settle on cold surfaces.

Everyday activities such as cooking, showering, washing clothes and even breathing release moisture into the home. When humid air comes into contact with colder surfaces like windows, walls or ceilings, condensation can form. If left unchecked, this can lead to mould growth, damp patches and poor indoor air quality.

An MVHR system continuously extracts moisture-laden air from areas such as bathrooms, kitchens and utility rooms, while supplying fresh, filtered air to living spaces and bedrooms. This constant air exchange helps maintain balanced humidity levels throughout the home and prevents excess moisture from building up.

Unlike opening windows, which provides only temporary ventilation and can result in heat loss, MVHR delivers controlled, year-round ventilation while recovering heat from the extracted air. This helps create a healthier and more comfortable indoor environment without compromising energy efficiency.

By controlling humidity and improving airflow throughout the property, MVHR can significantly reduce condensation and help prevent the conditions that allow mould and damp-related problems to develop.

MVHR is not a heating system, so it won't actively heat your home. However, it can help your home feel more comfortable and reduce heat loss by recovering warmth that would otherwise be lost through ventilation.

In a traditional ventilation system, warm indoor air is extracted and replaced with colder outdoor air. An MVHR system works differently by transferring heat from the outgoing stale air to the incoming fresh air through a heat exchanger. This means the fresh air entering your home is pre-warmed before it is distributed throughout the property.

As a result, your heating system does not have to work as hard to warm incoming air, helping to maintain a more consistent indoor temperature and improve overall energy efficiency.

Many homeowners find that their home feels more comfortable with MVHR because fresh air is supplied without the cold draughts often associated with opening windows or using traditional ventilation methods. The continuous circulation of fresh, tempered air can also help eliminate cold spots and create a more balanced indoor environment.

While MVHR should not be considered a replacement for central heating, it can play an important role in reducing heat loss, improving comfort and supporting the overall energy efficiency of your home.

The cost of an MVHR installation can vary significantly depending on the size and layout of the property, the complexity of the installation and the specification of the system being installed.

Factors that can influence the overall cost include the size of the MVHR unit, the amount of ductwork required, the accessibility of installation routes, the number of rooms being ventilated and whether the system is being installed in a new-build, renovation or existing property.

In general, installing MVHR during a new-build or major renovation project is often more straightforward and cost-effective, as ductwork can be incorporated into the building design from the outset. Retrofitting an MVHR system into an existing home may require additional work to accommodate the ducting and ventilation unit, which can affect installation costs.

To help homeowners, self-builders and contractors understand the requirements of their project, we offer a free MVHR design service. Our team will assess your property plans and ventilation requirements, providing a tailored system design and quotation to ensure you receive the most suitable solution for your home.

While MVHR represents an upfront investment, many homeowners consider the long-term benefits worthwhile. These include improved indoor air quality, reduced condensation and damp, enhanced comfort and improved energy efficiency through heat recovery.

The best way to obtain an accurate installation cost is to take advantage of our free design service. This allows the system to be designed around the specific requirements of your property and ensures you receive a solution that delivers the best performance and value for your home.

If you are experiencing little or no airflow from your MVHR vents, there are several possible causes, many of which can be resolved with routine maintenance or simple checks.

One of the most common reasons is dirty or blocked filters. As filters collect dust and airborne particles, airflow through the system can become restricted. Cleaning the internal extract valve filters every three months and the unit filters every six months will help maintain proper airflow. If your system is fitted with an optional pollen filter, this should be replaced every six months.

Another possible cause is that the system is not operating correctly due to a fault, incorrect settings or a power supply issue. Check that the unit is switched on and that there are no warning lights or fault codes displayed on the controller.

Reduced airflow can also occur if vents have been accidentally closed, covered by furniture or obstructed by dust and debris. It is important to keep supply and extract valves clear and avoid adjusting them unless advised to do so, as this can affect the balance of the system.

If the system has recently been installed, poor airflow may indicate that commissioning has not been completed correctly or that the airflow settings require adjustment.

If you have checked the filters, vents and system controls and are still experiencing poor airflow, we recommend contacting our team for assistance. A professional inspection can identify whether there is a blockage, system fault or commissioning issue affecting performance.

Regular maintenance and correct commissioning are key to ensuring your MVHR system continues to provide the fresh, filtered air and balanced ventilation it was designed to deliver.

Yes, MVHR systems work all year round, including during the summer months.

While the primary purpose of MVHR is often associated with recovering heat during colder weather, the system continues to provide an important ventilation function throughout the summer by supplying fresh, filtered air and removing stale, humid air from the home.

Many modern MVHR units include a summer bypass feature. When outdoor temperatures are warmer, the summer bypass automatically diverts the incoming air around the heat exchanger, preventing unwanted heat recovery. This allows cooler outdoor air to enter the home without being warmed by the extracted indoor air.

During warmer weather, MVHR can help maintain good indoor air quality, control humidity and remove excess heat generated by everyday activities such as cooking, showering and household appliances. It also allows fresh air to circulate throughout the property without the need to rely solely on opening windows.

Although MVHR is not a replacement for air conditioning and does not actively cool a home, it can help improve comfort during summer by providing continuous ventilation and making the most of cooler outdoor temperatures, particularly during the evening and overnight periods.

MVHR is not an air conditioning system, so it does not actively cool your home. However, it can help improve comfort during warmer weather by providing continuous ventilation and fresh air throughout the property.

Many modern MVHR systems include a summer bypass function. During warm weather, the summer bypass automatically directs incoming air around the heat exchanger, preventing it from being warmed by the outgoing air. This allows the system to take advantage of cooler outdoor temperatures, particularly during the evening and overnight periods.

By continuously removing stale air and supplying fresh air, MVHR can help prevent rooms from becoming stuffy and assist with controlling humidity levels during the summer months. This can create a more comfortable indoor environment, especially in well-insulated homes.

Our systems also include a dedicated button that allows the fresh air supply fan to be switched off when windows are open. This gives homeowners the flexibility to enjoy natural ventilation during warm weather without the system working against the airflow created by open windows. Once the windows are closed, the MVHR system can be returned to normal operation to continue providing balanced ventilation.

While MVHR will not lower indoor temperatures in the same way as air conditioning, it can help improve comfort, maintain good indoor air quality and make the most of cooler outdoor air during the summer months.

While MVHR is not a legal requirement in most new-build homes, effective ventilation is. As modern homes become increasingly airtight to meet energy-efficiency standards, natural ventilation through gaps and draughts is significantly reduced. Without a suitable ventilation strategy, moisture, pollutants and stale air can build up inside the property.

MVHR is one of the most effective ways to provide the continuous fresh air a modern home needs while minimising heat loss. Unlike traditional extract fans, an MVHR system recovers heat from the air being extracted and uses it to temper incoming fresh air, helping to improve comfort and energy efficiency.

Many self-builders, developers and homeowners choose MVHR because it provides whole-house ventilation, helps prevent condensation and mould, improves indoor air quality and reduces the need to open windows for fresh air.

Whether you need MVHR depends on your home's design, airtightness and ventilation requirements. However, for many modern new-build properties, MVHR is widely considered the best long-term solution for maintaining a healthy, comfortable and energy-efficient living environment.

The MVHR unit is typically installed in a location that is easily accessible for maintenance while minimising noise within the living areas of the home.

Common installation locations include loft spaces, utility rooms, plant rooms, cupboards, garages and dedicated service areas. The best location will depend on the layout of the property, the available space and the most practical routes for the ductwork.

When selecting a location, it is important to ensure there is sufficient space around the unit for filter changes, routine maintenance and servicing. The unit should also be positioned to allow efficient duct runs to the rooms being ventilated, helping to maximise system performance and minimise installation costs.

In new-build properties, the MVHR unit is often incorporated into the home's design from the outset. In existing homes and renovation projects, the unit can usually be installed in a loft, utility room or other suitable service space with careful planning.

As part of our free MVHR design service, we assess each property individually and recommend the most suitable location for the unit, ensuring the system delivers optimal performance, ease of maintenance and long-term reliability.

Yes, MVHR can be an excellent way to achieve compliance with Approved Document F (Ventilation).

Part F sets out the ventilation requirements that homes must meet to ensure a healthy indoor environment. Rather than specifying a particular type of system, it defines the airflow rates and ventilation performance that must be achieved.

A properly designed MVHR system can meet these requirements by continuously supplying fresh air to habitable rooms, such as bedrooms and living areas, while extracting stale, moisture-laden air from kitchens, bathrooms, utility rooms and WCs. This helps maintain good indoor air quality and control humidity throughout the home.

To achieve Part F compliance, the MVHR system must be correctly sized for the property, designed to deliver the required airflow rates and professionally commissioned once installed. During commissioning, airflow rates are measured and adjusted to ensure the system performs in accordance with the design specification and Building Regulations requirements.

MVHR is particularly popular in modern, airtight homes where natural ventilation alone may not be sufficient to provide the required levels of fresh air. By combining effective ventilation with heat recovery, MVHR can help homeowners meet Part F requirements while also improving energy efficiency and indoor comfort.

When properly designed, installed and commissioned, MVHR provides a reliable and effective route to achieving Part F compliance in both new-build and renovation projects.

Regular filter maintenance is essential to keep your MVHR system operating efficiently. If filters are not cleaned or replaced as recommended, they can gradually become blocked with dust, dirt and airborne particles.

As filters become clogged, airflow through the system can be restricted. This means the MVHR unit has to work harder to move air around the property, which can reduce efficiency and increase energy consumption. Reduced airflow can also affect the system's ability to remove moisture and provide the fresh air needed to maintain a healthy indoor environment.

Over time, neglected filters can lead to poorer indoor air quality, increased dust levels and reduced heat recovery performance. In some cases, homeowners may notice rooms feeling less fresh, higher humidity levels or an increase in condensation.

For systems fitted with an optional pollen filter, failing to replace the filter at the recommended intervals can reduce its ability to capture pollen and other fine particles, making it less effective for allergy sufferers.

To keep your MVHR system performing at its best, we recommend cleaning the internal extract valve filters every three months, cleaning the unit filters every six months and replacing any pollen filters every six months. Following this simple maintenance routine will help ensure reliable performance, efficient operation and excellent indoor air quality for years to come.

An MVHR system should not normally blow cold air into your home. The incoming fresh air is typically warmed through the heat recovery process before it is distributed throughout the property.

However, there are several reasons why the air from the vents may feel cooler than expected.

During colder weather, the fresh air supplied by the system is usually cooler than the room temperature, even after passing through the heat exchanger. While the air has been warmed significantly, it is not heated to the same temperature as the air already inside the room. As a result, some homeowners may perceive the airflow as cool, particularly when standing directly beneath a supply valve.

In warmer weather, the system's summer bypass function may be active. This allows fresh air to bypass the heat exchanger and enter the home without heat recovery, which can make the incoming air feel cooler.

If the air genuinely feels cold, it could indicate a problem with the system. Dirty filters, a fault with the unit, incorrectly configured settings or issues with the heat exchanger can all affect heat recovery performance. Inadequate commissioning or airflow balancing may also impact how the system operates.

Start by checking that the filters are clean and that there are no fault codes displayed on the controller. If the problem persists, we recommend contacting our team for advice and further investigation.

A properly functioning MVHR system should provide a continuous supply of fresh, tempered air that helps maintain comfort while reducing heat loss and improving indoor air quality.

In most cases, MVHR ductwork does not require regular cleaning if the system is correctly designed, installed and maintained.

Our systems include filters within the extract valves and MVHR unit that help prevent dust and debris from entering and accumulating within the ductwork. By keeping these filters clean and following the recommended maintenance schedule, the amount of contamination entering the ducts is kept to a minimum.

Over time, a small amount of dust may naturally settle within the ductwork, but this is generally not enough to affect system performance. Regular cleaning of the extract valve filters every three months and the unit filters every six months is usually all that is required to keep the system operating efficiently.

Yes, MVHR can help support compliance with Approved Document L (Conservation of Fuel and Power) by improving the overall energy efficiency of a home.

Part L focuses on reducing energy consumption and carbon emissions in buildings. As modern homes become better insulated and more airtight, ventilation remains essential, but traditional ventilation methods can result in significant heat loss.

An MVHR system helps address this challenge by recovering heat from the stale air being extracted from the property and transferring it to the incoming fresh air. This reduces the amount of heat that would otherwise be lost through ventilation and helps lower the heating demand of the building.

Because MVHR improves ventilation efficiency while reducing heat loss, it can contribute positively to SAP calculations and the overall energy performance of a property. This is one of the reasons MVHR is commonly specified in energy-efficient homes, self-build projects and developments aiming for high EPC ratings.

While MVHR alone does not guarantee Part L compliance, it can form an important part of a wider energy-efficiency strategy alongside measures such as insulation, airtightness, efficient heating systems and renewable technologies.

When correctly designed, installed and commissioned, MVHR can help homeowners achieve a healthier, more comfortable and more energy-efficient home while supporting compliance with modern Building Regulations.

Yes, a whole-house MVHR system requires ducting to distribute fresh air throughout the property and extract stale air from key areas.

The ductwork forms an essential part of the system, connecting the MVHR unit to supply and extract valves located in different rooms. Fresh, filtered air is typically supplied to living rooms, dining rooms, studies and bedrooms, while stale, moisture-laden air is extracted from kitchens, bathrooms, utility rooms and WCs.

The amount and layout of ducting required will depend on the size and design of the property. In new-build homes, ductwork is usually incorporated into floors, ceilings or service voids during construction. In existing properties, duct routes can often be installed within loft spaces, cupboards, boxed-in areas or other suitable locations.

A well-designed ducting system is crucial to the performance of an MVHR installation. Correct duct sizing, routing and airflow balancing help ensure the system operates quietly, efficiently and delivers the required ventilation rates throughout the home.

As part of our free MVHR design service, we produce a tailored ducting layout for each project, ensuring the system is designed to suit the property and achieve the best possible performance.

A properly functioning MVHR system should not produce unpleasant smells. If you notice odours coming from the system, it is usually a sign that maintenance is required or that there is an issue that needs attention.

One of the most common causes is dirty filters. Over time, filters can collect dust and airborne particles, which may affect airflow and contribute to unwanted odours. Regular filter maintenance is essential to keep the system operating efficiently and maintain good indoor air quality.

In some cases, smells can be caused by a blocked or poorly maintained condensate drain. If water is not draining away correctly, stagnant water can develop within the system and create unpleasant odours.

Odours may also occur if extract valves in kitchens or bathrooms have become dirty, or if the system has been switched off for an extended period and stale air has accumulated within the ductwork.

For newly installed systems, it is not unusual to notice slight manufacturing or installation-related smells during the first few days of operation. These should disappear as the system settles into normal use.

If cleaning the filters and checking the basic maintenance items does not resolve the issue, we recommend contacting our team for advice. Persistent odours may indicate a fault, contamination within the system or a maintenance issue that requires further investigation.

Regular maintenance, including cleaning the internal extract valve filters every three months and the unit filters every six months, will help keep your MVHR system operating efficiently and your home's air fresh and clean.

Yes, in many cases MVHR can significantly reduce condensation and help prevent damp problems caused by excess moisture in the home.

Condensation occurs when warm, moisture-laden air comes into contact with colder surfaces such as windows, walls and ceilings. Everyday activities such as cooking, showering, drying clothes and even breathing generate large amounts of moisture. If this moisture is not effectively removed, it can lead to condensation, mould growth and damp-related issues.

An MVHR system continuously extracts humid air from areas such as bathrooms, kitchens and utility rooms while supplying fresh, filtered air to living spaces and bedrooms. By maintaining balanced ventilation throughout the home, it helps control indoor humidity levels and reduces the conditions that allow condensation and mould to develop.

MVHR is particularly effective in modern, well-insulated homes, but it can also provide significant benefits in existing properties where condensation, mould or poor ventilation are ongoing concerns.

It's important to note that while MVHR can help prevent moisture-related issues caused by inadequate ventilation, it will not resolve damp problems caused by building defects, leaks, rising damp or structural issues. A professional assessment can help identify the underlying cause of any damp problem and determine whether MVHR is an appropriate solution.

Yes, MVHR can help reduce excess humidity and maintain healthier moisture levels throughout your home.

Everyday activities such as cooking, showering, drying clothes and even breathing release moisture into the air. Without adequate ventilation, this moisture can build up, leading to condensation, mould growth and a generally uncomfortable indoor environment.

An MVHR system continuously extracts moisture-laden air from areas such as kitchens, bathrooms and utility rooms while supplying fresh, filtered air to living spaces and bedrooms. This constant air exchange helps prevent excess humidity from accumulating and keeps moisture levels under control.

By maintaining balanced ventilation throughout the property, MVHR can significantly reduce the risk of condensation and the damp-related issues that often result from high indoor humidity. Many homeowners notice that windows remain clearer, rooms feel fresher and moisture-related problems are reduced after installing an MVHR system.

It's important to note that MVHR is designed to control excess humidity, not remove all moisture from the air. A properly functioning system helps maintain comfortable humidity levels rather than creating an overly dry environment.

For homes affected by condensation, mould or poor ventilation, MVHR can be one of the most effective long-term solutions for managing indoor humidity and improving overall comfort.

A summer bypass is a feature found in many MVHR systems that helps prevent unwanted heat recovery during warmer weather.

In normal operation, an MVHR unit recovers heat from the warm air being extracted from the home and transfers it to the incoming fresh air. This is highly beneficial during colder months, helping to reduce heat loss and improve energy efficiency.

During the summer, however, recovering heat is often unnecessary. When the outdoor temperature is warmer than the indoor temperature, the summer bypass automatically directs incoming air around the heat exchanger rather than through it. This prevents the fresh air from being warmed by the extracted air before it enters the home.

By bypassing the heat recovery process when conditions are suitable, the system can help make the most of cooler outdoor temperatures, particularly during the evening and overnight periods. This can improve comfort within the home while still providing the continuous fresh air and ventilation benefits of MVHR.

It's important to note that a summer bypass does not provide air conditioning or actively cool the property. Instead, it helps prevent unnecessary heat gain and allows the ventilation system to operate more effectively during warmer weather.

Yes, MVHR can help create a more comfortable indoor environment for allergy sufferers by continuously supplying fresh, filtered air throughout the home.

Unlike opening windows, which can allow pollen, dust and other airborne particles to enter the property, an MVHR system filters the incoming air before it is distributed to living spaces and bedrooms. This can help reduce the amount of airborne contaminants entering the home and improve overall indoor air quality.

All of our MVHR systems include filters that remove dust and airborne particles from the incoming air. For those who suffer from hay fever or pollen allergies, we also offer an optional pollen filter that provides enhanced filtration by capturing a greater proportion of pollen and other fine particles before they enter the property.

Many homeowners with allergies find that having a continuous supply of filtered fresh air reduces the need to open windows, particularly during periods of high pollen levels. This can help create a cleaner and more comfortable indoor environment throughout the year.

To maintain effective filtration, regular filter maintenance is essential. Internal extract valve filters should be cleaned every three months, unit filters should be cleaned every six months, and optional pollen filters should be replaced every six months.

While MVHR is not a medical treatment for allergies, it can play an important role in improving indoor air quality and reducing exposure to airborne allergens within the home.

A small amount of water inside an MVHR system is completely normal. As warm, moisture-laden air passes through the heat exchanger, condensation forms and is collected within the unit before being safely discharged through the condensate drain.

However, if water is leaking or dripping from the outside of the MVHR unit, this usually indicates a problem that should be investigated.

One of the most common causes is a blocked or incorrectly installed condensate drain. If the condensate cannot drain away properly, water can build up inside the unit and eventually overflow. This can occur if the drain becomes blocked with debris or if the pipework does not have the correct fall.

Water leaks can also occur if the condensate pipe has become disconnected, damaged or frozen during very cold weather. In some cases, poor installation or inadequate insulation of the condensate pipework can contribute to drainage problems.

If you notice water leaking from your MVHR unit, we recommend checking that the condensate drain is clear and functioning correctly. If the issue persists, the system should be inspected by a qualified engineer to identify and resolve the underlying cause.

Addressing the problem promptly can help prevent damage to the unit and ensure the MVHR system continues to operate efficiently and reliably.

Yes, an MVHR system can help reduce heating bills by recovering heat that would otherwise be lost through ventilation.

In a traditionally ventilated home, warm air is extracted and replaced with colder outdoor air, which then needs to be heated. An MVHR system works differently by transferring heat from the outgoing stale air to the incoming fresh air through a heat exchanger. This means the fresh air entering the home is already pre-warmed, reducing the demand on the heating system.

The level of energy savings depends on several factors, including the property's insulation levels, airtightness, heating system and how the ventilation system is designed and commissioned. In modern, well-insulated and airtight homes, the savings can be particularly significant because a greater proportion of heat is retained within the building.

While reducing heating costs is an important benefit, MVHR should not be viewed solely as an energy-saving measure. It also provides continuous fresh air, helps control condensation and humidity, improves indoor air quality and creates a more comfortable living environment throughout the year.

Although every property is different, many homeowners find that the combination of improved energy efficiency, healthier indoor air and enhanced comfort makes MVHR a worthwhile long-term investment.

An MVHR system should be serviced regularly to ensure it continues to operate efficiently and provide good indoor air quality.

For most homeowners, routine maintenance consists of cleaning the internal extract valve filters every three months and cleaning the unit filters every six months. If your system is fitted with an optional pollen filter, this should be replaced every six months to maintain its effectiveness.

In addition to routine filter maintenance, we recommend having the system professionally inspected and serviced periodically. A service visit allows key components such as the fans, heat exchanger, condensate drain and controls to be checked, ensuring the system is operating correctly and efficiently.

Yes, commissioning is an important part of achieving Building Regulations compliance for an MVHR system.

Building Regulations require ventilation systems to deliver the correct airflow rates throughout the property. Simply installing an MVHR system is not enough; it must also be tested and adjusted to ensure it is operating in accordance with the design specification and the requirements of Approved Document F (Ventilation).

During the commissioning process, airflow rates are measured at each supply and extract valve using specialist equipment. The system is then balanced and adjusted to ensure the correct amount of fresh air is being supplied and stale air is being extracted from each room.

Once commissioning has been completed, the airflow results are recorded and commissioning documentation is produced. This information is often required by Building Control as evidence that the ventilation system meets the required standards.

Without proper commissioning, an MVHR system may not provide adequate ventilation, which can lead to poor indoor air quality, increased condensation, excessive noise and reduced energy efficiency. It may also result in the system failing to meet Building Regulations requirements.

Whether the system has been professionally installed or self-installed, commissioning is the final and essential step in ensuring the MVHR system performs correctly and complies with current Building Regulations.

Yes, one of the primary benefits of an MVHR system is improved indoor air quality.

MVHR works by continuously removing stale, moisture-laden air from areas such as kitchens, bathrooms and utility rooms while supplying fresh, filtered air to living spaces and bedrooms. This constant air exchange helps reduce the build-up of pollutants, odours, humidity and airborne contaminants within the home.

The filters within an MVHR system can also help reduce the amount of dust, pollen and other outdoor particles entering the property, making the indoor environment cleaner and more comfortable. This can be particularly beneficial for allergy sufferers and those sensitive to airborne pollutants.

Unlike relying on opening windows, MVHR provides controlled, whole-house ventilation throughout the year, helping to maintain fresh air levels while minimising heat loss and external noise.

By delivering a continuous supply of fresh, filtered air, MVHR helps create a healthier, more comfortable living environment and can contribute to better overall wellbeing for occupants.

Yes, many of our customers choose to install their own MVHR systems, particularly on self-build and renovation projects.

We offer three levels of support depending on how involved you would like us to be:

• Materials Only – We supply the complete MVHR system and components for you to install yourself.

• Materials & Commissioning – You install the system, and we return once the installation is complete to commission and balance the system.

• Materials, Installation & Commissioning – We supply, install and commission the entire system for a complete turnkey solution.

For many renovation projects, the Materials & Commissioning option is particularly popular. Renovations are often completed in stages, making it easier for homeowners or builders to install the ductwork and components as work progresses. Once everything is in place, we can commission and balance the system to ensure it is operating correctly and delivering the required airflow rates.

We have successfully worked with many customers who have installed their own systems, and this can be a cost-effective approach when carried out carefully and in accordance with the design drawings.

Where we undertake the installation, the work can typically be completed within a couple of days. However, on projects that are progressing gradually, it can become costly and impractical for installers to make multiple return visits as different areas of the property become accessible. In these situations, self-installation followed by professional commissioning is often the most efficient and economical solution.

Whichever option you choose, proper commissioning and airflow balancing are essential to ensure the system performs efficiently, quietly and in accordance with the design specification.

Yes, one of the often-overlooked benefits of MVHR is that it can help reduce the amount of external noise entering your home.

Traditional ventilation often relies on opening windows or using trickle vents to bring fresh air into the property. While effective for ventilation, these methods can also allow unwanted noise from traffic, aircraft, neighbours, construction work and other outdoor sources to enter the home.

An MVHR system provides a continuous supply of fresh, filtered air without the need to keep windows open. This means homeowners can maintain good indoor air quality and comfortable ventilation while keeping external noise to a minimum.

This benefit is particularly noticeable in properties located near busy roads, flight paths, schools, town centres or other noisy environments. Many homeowners find that bedrooms are quieter at night, helping to create a more peaceful and comfortable living environment.

While MVHR is not a soundproofing system, the ability to keep windows closed while still enjoying fresh air can make a significant difference to overall noise levels within the home.

By combining effective ventilation with reduced reliance on open windows, MVHR can help create a quieter, healthier and more comfortable indoor environment throughout the year.

The time required to install an MVHR system depends on the size of the property, the complexity of the design and whether the project is a new build, renovation or retrofit installation.

For most new-build properties, a professional MVHR installation can typically be completed within a couple of days. This is often the most straightforward scenario, as the ductwork can be installed while the building is under construction and access to ceilings, floors and service areas is readily available.

Renovation and retrofit projects can take longer depending on the stage of the building works and how easily duct routes can be accessed. In many cases, homeowners or builders choose to install the ductwork themselves as the project progresses, allowing the MVHR system to be fitted alongside other trades without delaying the overall build schedule.

If you choose our Materials, Installation & Commissioning package, we will typically complete the installation and commissioning over a short, planned period. However, where a project is being completed in phases, it is often more practical and cost-effective for the system to be installed gradually, with final commissioning carried out once the property is ready.

The best way to determine installation timescales is to discuss your project with our team, as every property and build programme is different.

No, MVHR systems are designed to be highly energy efficient and typically use relatively little electricity.

An MVHR unit uses low-energy fans to continuously extract stale air from the home and supply fresh, filtered air. While the system does require electricity to operate, the amount of power consumed is generally low, particularly when compared to many other household appliances.

In most homes, the electricity used to run the system is often offset by the energy savings achieved through heat recovery. By recovering heat from the extracted air and using it to warm incoming fresh air, MVHR helps reduce the amount of energy needed to heat the property.

The exact electricity consumption will depend on factors such as the size of the property, the airflow rates required and the efficiency of the MVHR unit itself. A well-designed and properly commissioned system will operate efficiently while providing continuous ventilation and maintaining good indoor air quality.

Rather than being a significant energy user, MVHR is widely regarded as one of the most energy-efficient methods of providing whole-house ventilation, helping homeowners enjoy fresh air, reduced condensation and improved comfort without a substantial impact on electricity costs.

Yes, blocked or dirty filters can have a significant impact on the performance of an MVHR system.

Filters are designed to capture dust, dirt and airborne particles before they enter the MVHR unit and ductwork. Over time, these filters become clogged and can restrict airflow throughout the system if they are not cleaned or replaced as part of regular maintenance.

Reduced airflow can make it more difficult for the MVHR system to supply fresh air and extract stale, moisture-laden air from the home. This can lead to poorer indoor air quality, increased humidity levels, condensation issues and reduced comfort for occupants.

Blocked filters can also cause the MVHR unit to work harder to maintain airflow, potentially increasing energy consumption and placing unnecessary strain on the system's fans and components. In some cases, homeowners may notice reduced airflow from vents, increased noise levels or fault warnings from the unit.

To keep your MVHR system operating efficiently, we recommend cleaning the internal extract valve filters every three months and cleaning the unit filters every six months. If your system is fitted with an optional pollen filter, it should be replaced every six months to maintain effective filtration.

Regular filter maintenance is one of the simplest and most important ways to ensure your MVHR system continues to provide fresh, filtered air, efficient heat recovery and reliable long-term performance.

Yes, it is possible to install an MVHR system yourself and still comply with Building Regulations, provided the system is correctly designed, installed and commissioned.

Many self-builders and homeowners choose to carry out some or all of the installation work themselves, particularly on renovation projects where work is being completed in stages. Installing the ductwork and MVHR unit as the project progresses can often be more practical and cost-effective than arranging multiple installer visits throughout the build.

However, compliance with Approved Document F (Ventilation) depends on more than just the installation itself. The system must be correctly sized for the property, designed to achieve the required airflow rates and professionally commissioned once installation is complete.

During commissioning, airflow rates are measured and balanced using specialist equipment to ensure the system is delivering the correct levels of ventilation throughout the home. Commissioning results are then recorded and can be provided as evidence for Building Control where required.

Many of our customers choose our Materials & Commissioning package, where we supply the system and the customer completes the installation. Once the installation is finished, we commission and balance the system to ensure it performs correctly and meets the necessary ventilation requirements.

As long as the system is properly designed, installed in accordance with the design drawings and professionally commissioned, a self-installed MVHR system can comply with current Building Regulations and provide the same performance benefits as a professionally installed system.

No, a pollen filter is not essential for every MVHR installation, but it can be a worthwhile upgrade for certain households.

All of our MVHR systems are supplied with standard filters that help remove dust and airborne particles from the incoming air, improving indoor air quality and protecting the system from contamination.

For homeowners who suffer from hay fever, pollen allergies or sensitivities to airborne particles, an optional pollen filter can provide additional protection by capturing a greater proportion of pollen and finer particles before they enter the home. This can help create a more comfortable indoor environment, particularly during the spring and summer months when pollen levels are at their highest.

Pollen filters do require additional maintenance and should be replaced every six months to ensure they continue to perform effectively. Over time, a clogged filter can restrict airflow and reduce filtration performance.

Whether you need a pollen filter depends on your individual circumstances. Many homeowners are perfectly happy with the standard filtration provided by an MVHR system, while allergy sufferers often find that upgrading to a pollen filter offers noticeable benefits to their comfort and wellbeing.

No, a properly designed MVHR system should not dry out the air in your home.

MVHR is designed to provide balanced ventilation by continuously removing stale, moisture-laden air and replacing it with fresh, filtered air. Its purpose is to control excess humidity and maintain healthy indoor air quality, not to remove all moisture from the indoor environment.

In homes with high humidity levels, homeowners may notice that the air feels fresher and less humid after an MVHR system is installed. This is because the system is helping to remove excess moisture that could otherwise lead to condensation, mould and damp-related issues. However, this should not result in the air becoming uncomfortably dry.

Maintaining the right balance of humidity is important for both comfort and health. A correctly commissioned MVHR system is designed to keep humidity levels within a comfortable range while ensuring the home remains well ventilated.

If the air in a property feels excessively dry, this is often related to other factors such as heating patterns, seasonal weather conditions or the property's overall ventilation strategy rather than the MVHR system itself.

By providing continuous, controlled ventilation, MVHR helps maintain a healthy and comfortable indoor environment with balanced humidity levels throughout the year.

If your MVHR unit displays a fault code, the first step is not to panic. Fault codes are designed to alert you to a specific issue and can often help identify the cause of the problem quickly.

Start by checking your user manual, as the meaning of fault codes can vary between different MVHR units. In some cases, the issue may be something simple, such as a maintenance reminder, a blocked filter or a temporary interruption to the power supply.

If the fault code relates to filter maintenance, clean or replace the filters as recommended and then reset the warning if instructed by the manufacturer. For our systems, the internal extract valve filters should be cleaned every three months, the unit filters cleaned every six months and any optional pollen filters replaced every six months.

If the fault remains after carrying out the recommended checks, or if the code relates to a fan, sensor, electrical component or another system fault, we recommend contacting our team for assistance. Providing the fault code and a brief description of the issue will help us diagnose the problem more quickly.

Most fault codes are intended to identify issues early, helping to prevent more serious problems and ensuring your MVHR system continues to operate efficiently and reliably.

Yes, an MVHR system will continue to operate if windows are open, but it may not work as efficiently as it was designed to.

MVHR systems are designed to provide controlled, balanced ventilation by supplying fresh air and extracting stale air at carefully calculated rates. When windows are opened, additional uncontrolled airflow enters the property, which can disrupt this balance and reduce the effectiveness of the heat recovery process.

Opening windows will not damage the system, and there may be times when you choose to do so, particularly during warm weather or to enjoy a natural breeze. However, one of the key benefits of MVHR is that it provides a continuous supply of fresh, filtered air without the need to open windows, helping to maintain indoor comfort while minimising heat loss, external noise and the entry of pollen and outdoor pollutants.

Many homeowners find that once an MVHR system is operating correctly, they feel less need to open windows because the home remains fresh and well ventilated throughout the year. However, there are still times when you may want to open windows to enjoy a natural breeze or increase airflow during warmer weather.

Some MVHR systems, including ours, feature a dedicated summer mode button that allows the fresh air supply fan to be temporarily switched off when windows are open. This helps avoid unnecessary energy use and prevents the system from working against the natural ventilation provided by open windows. When the windows are closed again, the MVHR system can simply be returned to its normal operating mode, ensuring the home continues to benefit from balanced ventilation and heat recovery.

For maximum energy efficiency and heat recovery performance, it is generally best to keep windows closed during colder months, allowing the MVHR system to operate as intended.

MVHR is widely regarded as an important component of Passivhaus design because it provides the continuous fresh air and energy-efficient ventilation required in highly airtight buildings.

Passivhaus homes are designed to achieve exceptionally low energy consumption while maintaining excellent indoor comfort and air quality. Because these buildings are extremely airtight, a mechanical ventilation system is essential to provide fresh air and remove moisture from the home.

While MVHR is commonly used in Passivhaus projects, not all MVHR units are certified for Passivhaus applications. Our MVHR units are not Passivhaus-certified, so they may not be suitable for projects that require specific Passivhaus-approved products as part of the certification process.

However, our systems still provide the key benefits associated with heat recovery ventilation, including continuous fresh air, improved indoor air quality, reduced condensation and enhanced energy efficiency. They are suitable for a wide range of new-build, self-build and renovation projects where Passivhaus certification is not a requirement.

If you are aiming to achieve formal Passivhaus certification, we recommend discussing your project requirements with your Passivhaus designer or consultant to ensure all specified products meet the relevant certification criteria.

For homeowners seeking a healthy, comfortable and energy-efficient home, an MVHR system can still play a valuable role, regardless of whether the property is being built to Passivhaus standards.

MVHR commissioning is the process of testing, adjusting and balancing the system to ensure it is delivering the correct airflow rates throughout the property.

Once the MVHR unit and ductwork have been installed, simply switching the system on is not enough. Every room requires a specific amount of fresh air supply or air extraction, and these airflow rates must be carefully measured and adjusted using specialist equipment.

During commissioning, an engineer will check that the system is operating correctly, measure the airflow at each valve and make any necessary adjustments to achieve the design specification. This ensures the system provides the correct level of ventilation in every room while maintaining balanced airflow throughout the home.

Proper commissioning is essential because an incorrectly balanced system can lead to poor indoor air quality, condensation issues, excessive noise, increased energy consumption and reduced heat recovery performance. Even a well-installed MVHR system may not perform as intended if it has not been commissioned correctly.

Commissioning is particularly important for homeowners who choose to install the system themselves. Many of our customers carry out their own installation work, and we then commission and balance the system once everything is complete. This provides the reassurance that the MVHR system is operating efficiently, quietly and in accordance with the original design.

In short, commissioning is the final step that turns an installed MVHR system into a properly functioning ventilation system, ensuring you receive the full benefits of fresh air, heat recovery and energy-efficient performance.

A high-quality MVHR system can provide many years of reliable service when properly maintained. Most MVHR units are designed for long-term operation and can often last 15–20 years or more.

The lifespan of an MVHR system depends on several factors, including the quality of the equipment, the standard of installation and how well the system is maintained over time. Regular cleaning of filters and routine servicing can help ensure the unit continues to operate efficiently and reduce unnecessary wear on key components such as the fans and heat exchanger.

While the MVHR unit itself may eventually require replacement, other parts of the system, such as the ductwork, can often remain in service for much longer when correctly installed and maintained.

Keeping filters clean is one of the most important ways to maximise the lifespan of the system. We recommend cleaning the internal extract valve filters every three months, cleaning the unit filters every six months and replacing any optional pollen filters every six months.

With proper maintenance and care, an MVHR system can provide decades of fresh, filtered air, improved indoor air quality and energy-efficient ventilation for your home.

Yes, many homeowners find that MVHR helps create a more comfortable sleeping environment.

Bedrooms can quickly become stuffy overnight as occupants breathe and release moisture into the air. Without adequate ventilation, carbon dioxide levels, humidity and stale air can build up, which may leave rooms feeling uncomfortable by the morning.

An MVHR system continuously supplies fresh, filtered air to bedrooms while removing stale air from elsewhere in the home. This helps maintain good indoor air quality throughout the night, creating a fresher and more comfortable sleeping environment.

MVHR can also help control humidity levels, reducing the likelihood of condensation forming on bedroom windows and helping to prevent the damp, uncomfortable conditions associated with excess moisture.

Another benefit is that fresh air can be provided without the need to leave windows open. This can help reduce external noise from traffic, aircraft or neighbouring properties, while also preventing pollen and other airborne particles from entering the room.

While MVHR is not a sleep aid, many homeowners report that bedrooms feel fresher, more comfortable and better ventilated throughout the night. By maintaining a consistent supply of fresh air and balanced humidity levels, MVHR can contribute to a healthier and more comfortable sleeping environment all year round.

Yes, MVHR systems help improve indoor air quality by filtering the air that enters your home.

All of our MVHR systems include filters that continuously remove dust, airborne particles and other contaminants from the incoming fresh air. This helps keep the indoor environment cleaner while also protecting the MVHR unit and ductwork from dust build-up.

For homeowners who suffer from hay fever or pollen allergies, we also offer an optional pollen filter upgrade. This enhanced filter is designed to capture a greater proportion of pollen and other fine particles before they enter the home, helping to create a more comfortable indoor environment during allergy seasons.

To maintain effective filtration and system performance, filters should be inspected and replaced regularly. Standard filters typically require periodic replacement, while pollen filters should be replaced every six months to ensure they continue to provide optimal protection.

By filtering incoming air before it is distributed throughout the home, MVHR systems can help reduce dust levels, improve indoor air quality and provide a fresher, healthier living environment all year round.