Both domestic and commercial premises require ventilation, it allows its occupants to breathe fresh, wholesome air whilst removing stale damp air and provides safe operation for combustion appliances. Opening doors and windows or using extractor fans often will achieve the above but at the cost of heat loss resulting in increasing running costs.
A Mechanical ventilation heat recovery (MVHR) will extract warm stale air from a kitchen or bathrooms through a series of concealed ducts and vents. This air is drawn through a heat exchanger where it passes over fresh air drawn from outside, the clean air absorbs the heat from the extracted warm air and is distributed around the property. This heat contributes to the heat load of the property as well as providing excellent health benefits. MVHR also supplies cool air when required by bypassing the heat exchanger, this is often ideal for hot summer nights.
The system uses simple controls often pre-set to extract air as quickly as it replaces it. Extraction rate can be boosted when multiple showers are in operation. Regular maintenance is essential as filters, grilles, fans and heat exchangers need to be kept clean.
MVHR is often easier and more cost effective to install in new builds where the concealed ducting can be hidden in pre-planned, fabricated voids. The heat exchanger itself can be located in the attic, airing cupboard, basement or garage.
MVHR systems work by combining supply and extract in one unit. Moisture-laden, stale air is extracted from ‘wet’ areas, such as kitchens and bathrooms.
The heat from this stale air is recovered via a heat exchanger, and this tempered air delivered into the living areas of the home.
As homes become increasingly airtight through efficiency measures such as insulation, draught-proofing and double-glazed windows, a lack of natural ventilation means that moisture created from everyday activities such as cooking, washing and even breathing remains in the home. With nowhere to go, this moisture collects on cold surfaces such as windows and outside walls and causes condensation, damp and mould growth, all of which contribute to poor indoor air quality.
An MVHR unit is constantly ventilating a property, meaning that everyday moisture has no time to settle on surfaces as it is extracted to the outside, eliminating the risk of structural and cosmetic damage caused by condensation and mould. They are also extremely efficient, being able to recover up to 91% of heat lost through extraction and transferring it to incoming air.