What is MVHR?
Mechanical Ventilation with Heat Recovery (MVHR) is a continuous source of ventilation that extracts stale, moisture-laden air from a building and resupplies fresh, filtered air back in, resulting in a comfortable and condensation free environment all year round. MVHR meets Building Regulations for new properties under System Four of Building Regulations Part F.
Why do I need MVHR?
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 (IAQ).
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.
How does it work?
MVHR systems continuously extract moist, stale and polluted air from the wet rooms of a property such as bathrooms, utility rooms and kitchens. This air is passed over a heat exchange cell which recovers and retains the heat that would otherwise be lost from the extracted air. This heat is then transferred to incoming fresh, filtered air that the unit is resupplying back into habitable rooms such as bedrooms and living rooms, resulting in minimal heat losses and a more comfortable indoor environment.
What products are available?
There are two types of MVHR systems available – whole house and single room. A whole house centralised system is typically installed in a loft space and is ducted to the occupied rooms of a property for extract and supply. Decentralised single room heat recovery systems are typically installed through outside walls and resupply fresh, tempered air into the room they are extracting. They are ideal for replacing inefficient extractor fans and when installed in multiple rooms, reap the same benefits as a whole house system.