The purpose of the system is to:

A – Ventilate
– provide adequate fresh air to the inhabitants,
– extract excessive moisture and polluted air,
– prevent the build up of pollutants and moisture,
– for a healthy indoor climate and in order to protect the building structure,

B – Recover heat
– Effectively recover the heat in the dwelling, such as internal and solar gains.
– without the heat losses that are associated with other forms of ventilation.

C – For some systems: Provide or supplement space heating (if this has been explicitly designed to do so)
The post heater in the supply ducting provides some of the space heating together with the other methods of heating, e.g. towel radiators. The post heater is operated by hot water and controlled by a room thermostat. The heat output of the heater increases with increasing water temperature and increasing air flow (speed setting 3). Once the room temperature has reached the desired level, the heater will switch off.

The HRV system is based on a balanced supply and extract of air on a continual basis. Only with a balanced air flow can maximum efficiency be achieved.

As the system operates on a different principle than air conditioning, windows and external doors can be opened as it is needed without endangering the functionality of the system, other than that heating energy is lost in the cold season.

The ventilation zones are distinguished between:
– supply rooms (habitable rooms),
– transfer rooms (hallways, stair cases, etc.) and
– extract rooms (kitchen, WC and wet room).

Ventilation levels:
The system is normally operated on three levels: normal, reduced and boost ventilation.
– level 1 = reduced: When the dwelling is un-occupied for a couple of hours.
– level 2 = normal: Whenever the house is occupied
– level 3 = boost level: When smells or excessive humidity need to be purged quickly. This setting is limited to normally 15 min after pressing the boost switch on the display or in the bathroom.
– Un-occupied: holiday mode. The ventilation is operated on the lowest level for 15min. per hour.

Please note that these are guidelines according to normal calibration methods, but the ventilation levels 1 and 3 can freely be changed to improve personal well-being.

Summer operation:
The summer bypass function provides fresh air and extraction in the warm season without heat recovery. The bypass opens and closes automatically according to extract air temperature levels. These levels can be changed according to your personal requirements.

Some systems, such as focus and climos, have a summer bypass simulation, which switches to supply only mode (without heat recovery) if the internal temperatures reach the threshold. In this mode, the extract function is functional only, when the boost is activated.

In summer the system can also temporarily be switched off (stand by) when sufficient ventilation is achieved by opening of windows and doors.

Filter changes and maintenance:
Please note that filters of MVHR systems need to be checked and changed regularly. Depending on the pollution levels, filters usually last between 4-12 months. They can be cleaned with a vaccum cleaner once, but need to be exchanged for new ones at least once per year. Replacement filters can be bought online at:

There are two filters in the MVHR unit: One intake filter and one extract filter. These are dust filters (G4). The intake filter can be changed over to pollen filter (F7). They can be accessed via two black access panels. Please note that the filters are directional and need to be placed into the unit that the arrow on the filter shows in the direction of the air flow.

If installed, there is also a filter in the defroster box which needs to be checked and changed.

The unit has got a timer which counts down for the next filter check. The interval can be adjusted and the timer reset by pressing the filter change button.

Maintenance: Every two years the system is to be maintained by a professional HRV technician.