Questions regarding ventilation units with integrated heat pump

Below we have listed some of the most common questions and answers
regarding ventilation units with an integral heat pump.
If you need further information, please contact one of our dealers or service partners.

Choose from the following topics:

  • Heat pumps in general
  • Economy
  • Service and maintenance
  • My house gets too hot in the summer
  • If your ventilation unit does not work as expected
  • When should I contact someone, and whom?

Heat pumps in general

A heat pump consists, roughly speaking, of 3 components: A compressor that compresses the gas and drives it around the system; an evaporator that extracts energy (heat) from the extract air; and a condenser that releases energy (heat) to the supply air when it is in heating mode. 

In cooling mode the cooling circuit is reversed and instead of heating the supply air, the supply air is cooled and the extract air is heated up.

Active heat recovery is not indicated in %, such as passive heat recovery, but as a COP (coefficient of performance). COP indicates the energy output in kW compared with the energy in kW used for operation. A COP of 4 therefore means that for every 1 kW energy consumed by the heat pump, you get 4 kW energy in the form of heating.  With a heat pump, heat recovery therefore often exceeds 100%.

The heat pump has a reversible cooling circuit, which means that it can heat the supply air in the winter and cool the supply air in the summer.

Some of Nilan’s ventilation units are equipped with both a counterflow heat exchanger and a heat pump. Heat recovery is primarily carried out in the counterflow heat exchanger. However, if it becomes necessary to heat the dwelling by means of the supply air, the heat pump will start up and add more heat to the supply air. On the other hand, if cooling is required, the heat pump will reverse its cooling circuit and cool the supply air.

Ventilation units with an integral heat pump typically produce no more noise than an ordinary refrigerator or freezer.

Nilan produces ventilation units of different sizes and with duct connections placed on top or on the side of the unit. A top unit is typically installed in a tall cabinet, whereas a unit with duct connections on the side may be installed in, for instance, an unused attic. 

You do not need permission from the council in order to install a ventilation unit with heat recovery. The ventilation unit has a hermetically sealed cooling circuit, and it is therefore not a requirement that the unit is installed by a cooling technician. However, it is important that it meets the requirements specified in the Building Regulations regarding power consumption and heat recovery.

If you have no experience with dimensioning and installing ventilation units, we recommend that you get an expert to carry out the installation.


The power consumption depends on which model of ventilation unit you choose and how you use it. The power consumption of the heat pump depends on how much heating and/or cooling you require.

Please contact a dealer to get an estimate of the expected energy consumption in your dwelling.

A Nilan ventilation unit with a heat pump typically has a service life of more than 20 years.

Service and maintenance

There are no legal requirements preventing you from installing the ventilation unit yourself. You can download Installation and Software Instructions from our website under Downloads.

However, we recommend that a certified dealer carries out both installation and balancing. It requires expertise to install the ventilation unit so you achieve maximum operation with the lowest possible power consumption and low level of noise. 

It is important that you carry out maintenance to your ventilation unit in order for it to operate properly for many years.  You can compare it to a car that will eventually break down if it is not maintained.

The most important thing is to replace the filters when they are dirty, which typically means 4 times a year. In addition to this, the unit will need an annual check-up. You can find a detailed description of the maintenance requirements in the User Manual for the individual ventilation unit. The manual can be downloaded from Downloads.

Service of the heat pump must be carried out by a cooling technician.

You can buy filters online or over the phone from our dealers and service partners. Please state which ventilation unit and model you have and its approximate age so you are sure to get the correct filters.

The primary function of the filter is to protect the ventilation unit. You will be able to purchase the same type of filter that the unit had been fitted with when it was delivery, called ISO Coarse > 65% (previously called G4 filters)

If anyone in the household has allergies, we will recommend that you purchase a Pollen Filter ISO ePM1 50-65% (previously called an F7 filter). It filters out most of the pollen from the outdoor air. The filter area of the pollen filter is bigger than the standard filter and it therefore does not need replacing quite as often.

My house gets too hot in the summer

We are often asked if the ventilation unit can cool the dwelling in the summer, but this is not the case. The air exchange rate in a standard dwelling is ½ a time every hour. In order to achieve efficient cooling, however, the air exchange rate needs to be 7-10 times per hour. A ventilation unit for a dwelling is unable to do this.

Nonetheless, if you have no large, south-facing windows and you ensure that as little sun as possible touches your window panes, a ventilation unit could help cool the dwelling in the summer. 

The heat pump, which has been built into the ventilation unit, primarily serves to heat the dwelling in the winter. However, it is reversible and can therefore also cool the supply air with up to 10 °C in the summer. Due to the low air exchange rate, the cooling effect remains limited, though. 

When cooling the outdoor air, humidity is extracted from the supply air. Instead of an indoor temperature of e.g. 28 °C and a humidity level of 80%, you may end up with an indoor temperature of 25 °C and a humidity level of 60%.  It is easier to cope with the heat when the air humidity level is low indoors. That is why we call it “comfort cooling”.

If your ventilation unit does not work as expected

Contact the dealer from whom you purchased the unit. This is also the case if you purchased the unit online.

When should I contact someone, and whom?

If you want to purchase a Nilan ventilation unit, please contact one of our authorised dealers.  They will be able to advice you and ensure that you get a unit that meets exactly your requirements.

Contact the dealer from whom you purchased the unit. This is also the case if you purchased the unit online.

If the unit is not working and it is still under warranty, please contact the dealer from whom you purchased the unit. This is also the case if you purchased the unit online.

If the warranty has expired, please contact one of our service partners.

Nilan collaborates with some companies that carry out balancing. You can contact any of these to get your unit balanced.

The dealer from whom you have purchased the unit will be able to talk you through exactly how the unit works and how to operate it.

Remember the legally required inspection of your heat pump

If your heat pump contains more than 1 kg refrigerant it is required by law to have an annual inspection. This way you ensure that a leak or other issues are fixed.
Make an agreement for this inspection with a Nilan Service partner and ensure efficient and optimal operation of your heat pump.