Heat Recovery Ventilation Units (MVHR)

For example, in winter, the stale air inside the house is 21°C while the outside air is approximately 5°C. To avoid constantly filling the house with cold air, a HRV system is utilized. The stale air is first sent over a heat exchanger before being discharged outside.
This causes the heat exchanger to increase in temperature to 20°C.

The fresh air, which is at 5°C, is then passed through the other side of the heat exchanger without mixing with the outgoing stale air. As a result, the incoming fresh air rises to 19°C before it is blown throughout the house. This system helps to maintain a comfortable temperature inside the house and avoids the need for the radiators to heat up the cold outside air.

Whether your project is a new build, retrofit, renovation or you are updating a property, ventilation can be installed to any project!
It is common to hear that heat recovery does not work in older buildings, but this is not the case. It will still work but you may not get the highest efficiency from a system as you would if it were installed in a new home, but it is still a worthwhile and beneficial system.

Yes. Retrofitting the system into a single storey house is usually no problem but it is more difficult in two storey houses unless considerable renovation work is also being undertaken. However it is important to ensure the house is sufficiently air tight to warrant the spend. If not, Demand Controlled ventilation may be the more appropriate system.

MVHR systems are designed to provide ventilation and improve indoor air quality in a building. While they can recover and reuse heat from the outgoing stale air, they are not designed to be the primary source of heating for a home.

Instead, MVHR systems work in conjunction with a heating system, such as a boiler or heat pump, to help maintain a comfortable temperature inside the home. By recovering heat from the outgoing air and transferring it to the incoming fresh air, the MVHR system can help reduce the amount of energy needed to heat the home.

An MVHR system is usually around the size of a large boiler and has four ducts – two running outside and two for internal extract and supply, as well as pipework that connects each of your rooms to the system. It can be wall-mounted in a utility room or loft space.

The noise level of an MVHR System depends on several factors, such as the type of unit, the size of the property, and the location of the unit.

In general, MVHR systems are designed to operate at a low noise level to minimize any disturbance to the occupants of the property. Most modern MVHR systems are equipped with low-noise fans and are insulated to further reduce noise levels.

Correct sizing of the system is essential to keep noise to a minimum. An undersized unit running at higher speeds will contribute more noise to the building. It is also important to use a quality, correctly sized ducting system to reduce the noise levels. Slow moving air throughout the ducting system will generate less sound.

Yes, you can open the windows in a property with an MVHR (Mechanical Ventilation with Heat Recovery) system installed. The MVHR system is designed to work in conjunction with natural ventilation to help maintain good indoor air quality.

However, it’s important to note that opening the windows for extended periods may reduce the efficiency of the MVHR system. This is because the system is designed to control the flow of air in and out of the property to optimize heat recovery and ventilation. When windows are open, the MVHR system will still operate, but it will be unable to maintain the desired level of air quality and temperature.

We generally use a manifold ducting system using semi-rigid ducting as it’s more durable and has a longer lifespan. We also use small amounts of acoustic flexible duct, which reduce the sound of the machine entering the ducting system in strategic areas like connections to the fan unit. It is essential to use insulated ducting between the unit and the outdoor vents where the air is taken in and discharged through. This reduces cold bridging, condensation within the ducting and water vapour forming on the outside of the ducting.

Apart from keeping all the air vents clear and clean, the only maintenance is periodic filter changes. There are several filters which need to be changed to keep the air flowing properly. How frequently depends on where you live and how clean the air is. The filters keep your air clean, but are also needed to keep the system working properly. The kitchen extract filter may need changing/ cleaning more often than the others. Normally filters need to be changed every 12 months.

Even though an MVHR system should be left on all the time, the fans are powered by low energy motors. Depending on the size of property the annual cost will be around €80 to €100 a year which will be significantly outweighed by the savings made in heating costs for the home.