Heat recovery ventilators (HRVs)

Heat recovery ventilator operation 
HRVs remove stale air, while transferring heat to incoming fresh air.

A heat recovery ventilator (or HRV) is a ventilation system that is able to remove stale air and bring fresh air into the home, while at the same time using the heat from the air being removed to either heat or cool the incoming fresh air. These systems are popular in homes with a tight building envelope because of the degree of control they allow over both ventilation and heating systems.

Heat recovery ventilator (HRV) 
Heat recovery ventilators are complex but efficient devices.

How do HRVs work?

Heat recovery ventilators uses two ‘blowers’ to force stale air out of a property while drawing fresh in. As warm air is forced out, the system uses the heat in the air to actively heat or cool the air before it is vented inside (depending on what's required).

HRVs and the closely related energy recovery ventilators (ERVs), which also transfer humidity from warm to cool air so as not to dry it too much, uses heat exchange technology (similar to that which is in your car’s radiator or a refrigerative air conditioner) to precondition the incoming air. Inside is a series of narrow passages that allow the air to be cooled (or heated). They also contain highly efficient air filters (including HEPA filters) to remove pollen and pollutants from the incoming air, so as to purify it.

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How effective are HRVs?

How much heat can HRVs recover? It depends largely on the particular system and setup, but some HRVs can recover in excess of 80% of the heat from ventilated air. HRVs are a very efficient and effective way to ventilate and heat your home, although if you are considering one you should also be mindful of the fact that there are operating costs involved. Because HRVs are fully controllable and customisable they can be very energy efficient when used properly.

Advantages
  • More effective than natural ventilation
  • Air is cooled or warmed before it enters the home
  • Effective both in summer and in winter
Disadvantages
  • Expensive to buy
  • Requires electricity to operate
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