Installation and dimensioning
of heat recovery ventilation unit

How to dimension and install a Dantherm heat recovery ventilation unit

The heat recovery ventilation system should be dimensioned for an air change of 0,30 l/s pr. square metre heated floor area or with an increased air change from the kitchen, the bathroom, the toilet, the utility room and the basement of:

  • Kitchen: 20 l/s
  • Bathroom and toilet: 15 l/s
  • Toilet/utility room/basement room: 10 l/s

The heat recovery ventilation unit is placed either in the utility room or in the loft area. By means of ventilation ductings it is connected to the extraction outlets in the kitchen, the bathroom and the utility room, as well as to supply air grilles in the living rooms and bedrooms.

Here is a drawing showing where to place the ventilation unit (a horizontal model for loft installation):
  (Source: Danish "Videncenter for energibesparelser i bygninger").

The ventilation unit is supplied with fresh outdoor air from air intakes which are connected to the heat recovery unit by means of ventilation ducts (outdoor air intake to ventilation unit). The stale air is removed through the ventilation ducts to the exhaust air outlet. All four ducts are connected to the ventilation unit with a fire resistant, flexible connection to avoid vibrations in the ducts. The cooking hood must not be connected to the ventilation system as cooking exhaust air will grease up the ducting.

If the heat recovery ventilation unit is installed in the loft, it must be placed on a stable foundation which is strong enough to carry the weight of the unit and 1-2 men. The foundation must also be vibrationless. To eliminate vibrations a sandwich foundation can be built for placing the unit on it.  Dantherm heat recovery ventilation units for installation in the loft (HCH models) are supplied with a control panel with 10 m cable, so that the control panel can be placed on the ground floor.

The heat recovery ventilation unit should be placed in the middle of the area to be served. It is recommended not to place it just above a living room to avoid any noise nuisance.  It is recommended to leave enough place around the unit to provide for duct work, connection of electricity supply, and connecting a condensate drain. Dantherm heat recovery ventilation units with counterflow heat exchangers must be fitted with a condensate drain kit.

In order to supply the remaining 10-20 % heat in winter, the ventilation unit can be fitted with water after-heating coils. The water heating coils must be connected by an authorised plumber/heating engineer. The heat pipes must be insulated. The heat loss can also be covered by the radiators in the house.
Source: "Videncenter for energibesparelser".

For more detailed specifications we refer to the technical booklet.

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Heat recovery ventilation