8.3Mechanical ventilation with heat recovery

This chapter gives guidance on meeting the Technical Requirements for mechanical ventilation with heat recovery (MVHR) systems acceptable to NHBC.

Definitions for this chapter

Air valve
(extract and supply)
Wall or ceiling mounted fittings used to balance the flow rate of air between rooms; may be referred to as grilles.
Exhaust ductworkCarries air from the fan unit and exhausts it to the external atmosphere.
Intake ductworkCarries air from the external atmosphere to the MVHR fan unit.
MVHR fan unitUnit that contains the fan(s), heat exchanger and filter(s).
Service ductwork
extract and supply
Carries air between the air valves and the MVHR fan unit.
Terminal fittingsLocated on the outside of the building to finish the intake and exhaust ductwork.