HRV Overview.

‘Shut that door and don’t let the heat out’ is a familiar cry in winter. Heat recovery ventilation, also known as HRV or MVHR offers a solution, it brings fresh air into your home without letting the heat escape. Energywise Ireland are leading suppliers of heat recovery ventilation systems. We design and supply and if required install these systems in homes and commercial buildings.

Why do we need HRV?

Now days buildings are now a lot more insulated and air tight, so it is vital that a suitable ventilation system is in place. With the current building regulations, installing a heat recovery unit is becoming a necessity rather than a choice. It is important that you have adequate air supply to all rooms and extraction from bathrooms and kitchens. Insufficient ventilation can lead to mould growth, condensation damage and unhealthy living conditions. Our team at Energywise can advise you on the most suitable ventilation system to match your home’s airtightness level. Why not email us your drawings, our experts will design your system for you and provide you advice and a free no obligation quotation?

What is HRV?

HRV or a heat recovery ventilation system remove odour and humid air from kitchens and bathrooms. The same volume of clean, preheated air is supplied to bedrooms and living rooms. As much as 95% of the normally wasted heat is being recovered. Since the energy of the extracted air is transferred to the fresh. This means maximising energy for minimum cost. The filtered and, consequently, cleaner air increases the comfort for you and your family.


How does heat recovery ventilation work?

1. Heat recovery ventilation systems are designed to recover up to 95% of the heat normally lost through open windows, vents and other breakout points.

2. Fresh air is continuously drawn into the home via a low energy heat recovery ventilation unit, usually located in the attic or utility area.

3. Once passed through the heat exchanger within the HRV ventilation system, the warm, clean, fresh, filtered air is distributed around the home through a series of ducts. Since the energy of the extracted air is transferred to the fresh, cool outdoor air, 95% of the heat is retained. That means no waste of energy.

4. Air from wet rooms e.g. bathrooms, kitchens, etc. is continuously extracted and filtered back through the heat recovery ventilation unit. The heat from the extracted air is transferred to the fresh incoming air. HRV can also dissipate warm air from your home in Summer, bringing in cool, fresh air from outside.

5. With an auto summer by-pass, the HRV unit automatically controls whether to reclaim heat energy (or not) based on temperature. This ensures that your house does not get over-heated while still remaining air-fresh.



No is the short answer. A heat recovery ventilation system is purely to manage the ventilation of the building, providing fresh air and extracting stale air and steam. A heat recovery ventilation system will reduce the heat demand of the house regardless of the type of heating system as it reclaims a proportion of the heat that would have been lost in the air changes of the house.
A properly specified and installed heat recovery ventilation system should be barely audible if at all. However whenever the unit is on boost mode the ventilation rate is increased so more air is moving through the vents and the sound may become noticeable but this is generally only when someone is having a shower.
Some manufacturers in the past have toyed with this but have since discontinued with the principal. A cooker hood typically moves a lot of air, often more than the whole house ventilation rate would be, so to add this extra demand onto the heat recovery ventilation system would mean compromising the extract rate from the cooker hood or increasing the ventilation rate for the whole house by a lot. It is generally recommended to us a recirculating cooker hood with activated charcoal filter for dealing with the steam and odours from the cooker. With this the heat that the cooker produces is not just pumped outside as is done with an extractor hood. The heat recovery ventilation system would typically have an extract vent in the kitchen located between the cooker and the sink to extract whatever steam that escapes the cooker hood.
No. The heat recovery ventilation ducts (pipes) are all hidden above the ceiling level of the rooms. The only thing that is seen is the small white circular ceiling vent of which there would usually be one in each room.
The heat recovery ventilation unit itself is usually located either in the attic space or in a plant room where other services for the building would be located.
Not usually. There is usually a supply vent in the likes of bedrooms, living areas, sitting rooms etc. The extract vents would be in bathrooms, WCs, utility, en-suites etc. This arrangement allows for the fresh air to be fed into the rooms where you spend most of your time. With the extract in other rooms it causes the air to flow from supply rooms in the direction of extract rooms ensuring a cross ventilation of the whole building.
No. The heat recovery ventilation manages all the general ventilation as well as the extract ventilation for the building so extra wall vents are not required. The only exception is where there is a fire place or stove in a room which must have its own dedicated air supply. This is usually done by installing a vent pipe from outside directly to the location of the stove or fireplace so as to not cause a draught in the room.
The cost to run a heat recovery ventilation system per year depends on the size of the house. The larger the house the more air needs to be moved and so the fans have to work harder. A house of 250m2 would cost in the region of €40 to €60 per year to run. The same system would reclaim an energy value roughly equivalent to 200 litres worth of oil per year. Do I need bathroom fans with a HRV system? No. The heat recovery ventilation system manages the extraction of the steam from the bathroom and reclaims some of this heat to contribute to the heating of the building.
This depends on the air quality in the area and the amount of activity within the building. In some installations it is only necessary to vacuum the filters about once a year and change them every few years while in other installations the filters may need to be changed once a year.
Yes, it works independently of your heating system. The unit recovers the heat from the warm air in the house. It doesn’t matter how that heat was generated, whether by oil, gas, wood pellet, electricity, heat pump or any other source. However, it is important to choose a heating system that will suit your needs.
Enquire About HRV

Follow Us on Facebook!