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MVHR Units

MVHR units (Mechanical ventilation heat recovery)

There are many manufacturers of MVHR units.

The question is, which is most suitable for you?

At Airwave, we will always make a recommendation based on our experience and design requirements, however another brand of unit maybe desired by you, which will be accommodated.

The following characteristics should be considered when choosing a ventilation unit in order of importance as we do.

  • Unit size, the following is a simplified example of how a unit should be sized in accordance with building regulations Part F. note: this is a minimum requirement and is for dwellings only.Consider a 150m2 home calculated thus.Total floor area 150m2 x 0.3 = 45 litres/second x 3.6 = 162 m3/hour x 2 = 324 m3/h.

    Therefore your home requires >162 m3/hour to ventilate adequately, the MVHR unit should be running at as close to 50% of its capacity, in normal setting as possible and achieve >162m3/hour, to achieve this, the minimum size unit for your home should be as close to or greater than 324m3/hour for the following reasons.

    1. It keeps electrical running cost to a minimum, typically €60 per year or less running 24/7/365.
    2. Ensures maximum heat recovery efficiency, typically 90%.
    3. Less noise from the unit.
    4. It will prolong the life of the fan motors


    All MVHR manufacture's advise the above scenario.

  • Is a vertical or horizontal unit required? Normally vertical units used unless space is a major problem.

MVHR Horizontal unit

MVHR Units

MVHR Vertical unit

MVHR Units
  • Budget. Units come in all price ranges depending on their quality and function, at Airwave we generally recommend a mid-range cost unit representing best value for you.


  • Unit efficiency expressed as percentage of heat recovered, we do not recommend anything under 80%.


  • Consumption, SFP (specific fan power) watts/litre/second} example, 0.85 w/l/s, at Airwave we do not recommend a scenario producing a value over 1.0 w/l/s.


  • Warranty, Manufacturers usually give between two or three years warranty.


  • Building Energy Rating, If the unit supplied is not registered on the SAP Appendix, default efficiency values will have to be used by your BER assessor. This will have a negative effect on your BER.


  • Recommendation, It is always useful to get feedback from family and friends. We at Airwave are happy to have an unbiased chat with you to help make up your mind. Just give us a call or email.

We use the following leading brands of MVHR units: