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How MVHR Works

How MVHR (mechanical ventilation heat recovery) Works

The MVHR unit is a compact air handling unit that delivers efficient ventilation with highly efficient heat recovery, as well as cooling recovery for hot summer days.

The unit is very clever but also very simple. It draws in fresh air from outside, while at the same time extracting stale air from within the house. As the fresh air and stale air travel through the counter-flow heat exchanger inside the unit, the thermal energy from the used air can be taken and used to heat the fresh incoming air. Basically as a heat pump, it recycles 80% of the thermal energy from the air.

With virtually no moving parts, these units are virtually maintenance free and simply requires both filters to be changed at least once a year. Changing the filters is as simple as changing a light bulb.

This award winning heat recovery unit (MVHR) made from high quality Swedish technology, has been successfully used in for both low-energy and passive house designs for many years to meet the exacting Swedish Building Code and Passiv Haus standards. With the UK now well on the way, to catching up with Europe, with the introduction of the Code for Sustainable Homes; energy-efficiency products such as these, are an ideal alternative to traditional radiators and virtually eliminates the need to purchase energy. Your utility bills will be a fraction of what they are now, from day one with these types of heat recovery systems.

  • The fans  works with constant flow regulation (cruise control), which ensures the air flow is maintained at the correctly adjusted level and compensates for filter blockages. Comes with built-in, overheat protection.
  • The MVHR unit is fitted with an integrated electric afterheater (0.9 kW) which ensures the supply air temperature will not fall below the set temperature. As an optional extra, the unit can also be fitted with the following heating coils;
    • - 1.8 kW reinforced electric afterheater
    • - 1.6 kW water, or
    • - 2.8 kW reinforced water
  • If a water coil is used, connections are on top of the unit (dimension 3/8”) and include 2-way valve and valve motor.
  • The unit comes fitted with an automatic by-pass, which applies cooling recovery on hot summer days. Alternatively, an external cooling coil (EKB) can be used.
  • Counterflow Heat exchanger is fully sealed between the supply air side and the exhaust air side, to stop seepage of odours or contaminants between the old air and the new. This design also means wear and tear is now down to a minimum.
  • Silencers are designed and fitted to both supply air and exhaust air ducts. Located between the duct and the unit, a flexible silencer (Aku-comp) reduces the operational noise levels and prevents ‘eavesdropping’ between different rooms that are interlinked with the same part of the duct system.
  • The cooker fan is fitted with a separate fireproof spiral duct. The extract air is fed out via a roof hood (VHS) and the link between the cooker fan and kitchen flue is made using an approved hose (KF) and 2 quick-action clamps (SBF).
  • Air diffusers/valves (CTVK or STQA) can be wall or ceiling mounted and operate at low noise levels. The air discharged from the valve is mixed thoroughly with the room air, thus providing a draught-free air supply. Supply air is brought into rooms of long-occupation, such as living or bedrooms, while exhaust air is taken out of bathrooms, laundries and toilets.
  • The unit can be fitted with a fire function, to accommodate a modern fireplace.
  • The MVHR (mechanical ventilation heat recovery) unit comes with factory-fitted condensation drainage, to be connected to a drain in the floor. Alternatively, it is possible to provide the unit with a condensation evaporator (KAVK), as an optional extra when no external connection is required or possible.


For details of our range of MVHR Units go to our MVHR Units section.

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