How to adjust your
ventilation system?

A ventilation system must always be adjusted for the individual home to ensure balance between exhaust and supply air. Therefore, it is advisable to reserve ample time to adjust and regulate the system after installation.

If you don't know how much air passes in and out of the valves, you don't actually know whether the system meets the requirements for air change, or whether there is positive or negative pressure in the home.

  • If the system sucks out more air than it blows in, a negative pressure will develop, resulting in cold, unheated air entering through windows, doors and cracks in the vapour barrier. This can lead to draughts and higher heating costs.
  • High levels of negative pressure can also cause unpleasant odours and be dangerous if the house has a wood-burning stove, because the system will try to suck air down through the stove. A thorough adjustment is therefore extremely important if the home has a wood-burning stove or fireplace.
  • If the house takes in more air than is sent out, this will create positive pressure in the home and the heat recovery unit will not work optimally. The supply air becomes cold and there is a risk of draughts. If positive pressure is created in the home, you risk humidity in the house being pushed into the building structure, where it condensates and potentially causes rot and mould growth.

Get our full 32-page guide for selection and installation of residential ventilation right here: Selection Guide for residential ventilation

Air measuring equipment

Balancing the system requires professional air measuring equipment that can measure air volumes in the home.

  • On some of Dantherm's ventilation systems, air volumes can be adjusted on a potentiometer on the unit itself. On other systems, the air volumes are set using PC Tool or directly from the control panel on the unit.
  • Differential pressure gauges are used to measure the pressure difference at the heat exchanger's air intake and exhaust side. These measurements enable you to determine the correct air volume for the ventilation system.
  • Flow meters are used to regulate air flow to the valves in the rooms.
  • Dantherm recommends that balancing the system is performed by an authorised installer.


How to balance the system

The adjustments are based on how much air needs to be changed and what the distribution will be between humid rooms and living spaces.

The fitter must balance the air change by adjusting the unit's main ducts so that the system's intake and exhaust replace the correct amounts of air and ensure a balance between the amount of air that is blown into and sucked out of the home.

The air volume is divided between the various rooms so that there is always an amount of air in each room corresponding to its size.

The air flow is then fine-tuned at the valves until intake and exhaust are in balance, without this causing draughts in the rooms.

For more information, please download Dantherm’s full Selection Guide for residential ventilation.