Mechanical Ventilation

What is a Heat Recovery and Ventilation System?

A mechanical ventilation heat recovery system (MVHR) extracts warm, moist air from rooms such as kitchens and bathrooms. This is done through a concealed duct system. The air is passed through a heat exchanger then ducted outside.

Fresh air from outside is drawn in and passed through the heat exchanger, which warms it, and it’s then ducted to the living rooms and bedrooms. Some systems have a summer bypass feature so that when it’s warm outside, the air can bypass the heat exchanger to help keep the house cool.


  • The systems often have two speeds, so when the kitchen and bathrooms are being used – and producing lots of moisture – the extraction rate can be boosted.
  • MVHR will contribute to satisfying the requirements of Passivhaus Standards.
  • Systems are fitted with air filters, so they’re helpful in preventing potential allergens entering the house.


An MVHR system will need regular maintenance. The system needs to be kept in balance in terms of the supply and extraction of air. Filters, grilles, fans and heat exchangers need to be kept clean, too.

Where is the System Installed?

The system’s heat exchanger is generally fitted in the loft, although it could also be installed in a void in the eaves or ceiling, or a cupboard in the kitchen or utility room, or even in the garage. Consideration will need to be given to the positioning of the concealed ducting at planning stage.


Although the system can be fitted by a competent DIYer, changes to the building regulations in October 2010 mean that ventilation provision in new houses must be commissioned by a suitably qualified person. You should make sure that your system is commissioned on completion of the installation.

We can provide site support services, which includes a qualified engineer visiting the site to offer help and guidance to those who are undertaking the installation.

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