Mechanical Ventilation and Heat Recovery (MVHR)

MVHR systems are designed to continuously extract air from within a building and introduce fresh at the same rate; energy from the extracted air is transferred to the incoming cold air by means of a plate heat exchanger or thermal wheel.

Mechanical Ventilation and Heat Recovery

A Mechanical Ventilation with Heat Recovery system requires the installation of ducting to every major space. The system usually consists of a single unit which contains the heat exchanger and circulation fans - the unit is usually installed on the roof void, if space is available, but they are often small enough to be fitted in a cupboard space. 

A MVHR system has the advantage that the rate of air changes is fairly constant and does not vary depending on outside wind speeds or direction. But it is important that the inlet for the fresh and the outlet for the extracted air are kept well apart to avoid short circuiting where the extracted stale air is drawn back into the building.

What should I do?

Consider an MVHR system if you are building or refurbishing an airtight building.

WLGA - CLILC Llywodraeth Cynulliad Cymru / Welsh Assembly Government