Mechanical Ventilation Heat Recovery
The function of ventilation is to provide ‘good air quality”. Our bodies have two main intakes – food and air. For years we have had advice on quality food. Since we normally spend 80% of our time in indoor conditions good quality air is critical.
In a very well insulated house, which is designed as airtight, poor air quality can be a problem. The most energy efficient method of ventilation is mechanical ventilation with heat recovery.
Homes with well designed Mechanical Ventilation Heat Recovery (MVHR) systems have reduced heating bills and persons with asthma or hay fever type problems enjoy much improved health. There are now a number of asthmatic children who, since they moved into their new home with MVHR, no longer require their inhalers.
The quality of filters used in MVHR systems varies widely. The standard should be filters approved by the Asthma Society of Great Britain. The number of air changes is very important. Some systems are quoting heat recovery efficiencies of 95%+. The fact is, that if this is being achieved, then the air changes are inadequate, and quality of the air is being sacrificed. Some companies are now using duct sizes which are so small, that if adequate flow rates were possible, the system would be noisy.
Key requirements
- Quality Asthma Society approved filter
- Large, well designed ducts, well installed to deliver/extract air to/from each room
- Efficient heat recovery system
- EU7 filters with large surface area
- Beware – Poor design or inexperienced installers can cause problems
- Loss of privacy by “cross talk” – speech from one room being conveyed to another room
- Noise from the ventilation unit or air noise due to poor ducting
- If there is noise the system will be switched OFF
- Save money – seek independent advice to get it right first time