Buying and installing a heat pump checklist

A heat pump fits in almost every home. Which heat pump best suits your home depends, among other things, on how well your house is insulated and whether your heating system can heat the home well and comfortably with low temperatures. With the heat pump selection aid you can see whether your home is already suitable for a fully electric heat pump.

It is important that you know in advance how much power the heat pump should have. If the power is too low, your house will not be warm enough in severe frost, or the inefficient electric reheater will have to step in too much. Too much power is more expensive to purchase and causes problems when only a little heat is needed.

You can use this bandwidth as an estimate.

• How well your home is insulated.
• How warm you keep your home.
• Whether you have underfloor heating or radiators.
• How to ventilate the house: with ventilation grilles, demand-controlled mechanical extraction or with a system that recovers heat from the ventilation air.

Heat loss calculation

It is best to have a heat loss calculation made by a consultancy firm. That does cost money: up to a few hundred euros.

An expert will examine exactly what insulation your house has, what ventilation system it has and what the heating capacity is (radiators, underfloor heating). Using a special computer program, he then calculates how much heat your house loses and how much power the heat pump needs. If the insulation of your house is not yet sufficient, he also gives advice on how you can improve it and what the effect is. He can do the same for ventilation.

Energy consumption on a cold day

You can also determine the power based on energy consumption on a very cold day.

How does it work? If it is very cold (rule of thumb: minus 5 degrees), measure your gas consumption for 24 hours (longer is also allowed). It is important that you do not turn the heating down much at night, at most 1 or 2 degrees lower than during the day. And that you use the shower and bath 'normally' (as you would otherwise). At the start you write down the meter reading and at the end (after at least 24 hours) you do so again. You then know how many cubic meters of gas you have used. This allows you to calculate the average power.

Other methods

Installers also use other methods to determine the power, but these are less reliable. For example, an estimate based on square meters of living space in combination with year of construction or energy label. Or an estimate based on gas consumption per year. But these methods do not take a number of things into account (for example the type of home and heating behavior).

An all-electric ready heat pump has a comparable capacity as a fully electric heat pump. However, you initially use it as a hybrid, together with your central heating boiler. This can be useful if your home is being adapted in the short term to switch off gas completely. Do you have good insulation, a suitable delivery system and do you cook electrically? Then, with a few adjustments, you can use the same heat pump completely electrically.

A hybrid heat pump works with the existing heating (radiators, convectors, underfloor heating, etc.) in the house. The greater the capacity of your heating, the more efficiently the heat pump works, the less often the central heating boiler has to be switched on, and the more natural gas you save.

A fully electric heat pump works at lower temperatures (35 to 55 degrees) than your central heating boiler (60 to 80 degrees). Your heating must therefore be 'large enough' to heat your house (in other words: have enough surface area). Underfloor heating and wall heating are very suitable in combination with a heat pump. But existing radiators may be too small or too thin. You can then replace some radiators with larger or thicker ones (with more plates and slats) or with convectors. There are also special radiators for a low temperature.

In a post-insulated house, the existing radiators are often already suitable or can be made suitable with minor adjustments.

Adjusting the installation

In order for the system to operate as efficiently as possible, the heating system must be properly adjusted. This concerns the (temperature) settings of the hybrid heat pump and the central heating boiler, at which day temperature and heat demand the central heating boiler switches on and whether there is sufficient water pressure in the central heating circuit. The heat must also be distributed as well as possible across the radiators and other heating elements in the house. The latter is also called water-side adjustment. This adjustment is mandatory when installing a new central heating boiler or hybrid heat pump. If it is not technically possible, an exception will be made.

An air-water heat pump has an outdoor unit, which resembles an air conditioner. The fan of this outdoor unit makes noise when the heat pump is running. This is especially true in autumn, winter and early spring, when you have the windows closed and therefore hear less outside noise. But a fully electric heat pump can also turn on at night and also works for hot water in the summer.

There are legal requirements for the maximum noise that an outdoor unit of a heat pump may produce. This is measured on the boundary with the neighbors (the property boundary). During the day this may not be more than 45 decibels and in the evening and night no more than 40 decibels. Place the outdoor unit in a place where it will not bother you or the neighbors much. The installer can advise you on installation and how to meet the noise requirements. There are sound-absorbing cabinets for sale.

Research shows that almost three-quarters (72 percent) of heat pump owners never experience noise pollution from the heat pump. Are you unsure whether you will find the sound annoying? Go listen to someone who has a heat pump and find out how you experience the sound.

For example, where do you place the outdoor unit?

• On the side of your house.
• Near or behind a shed or in an outdoor cupboard (you can also put it out of sight).
• On the roof of an extension (if the roof is not sensitive to vibrations).
• Not too close to the neighbors.
• Not near a bedroom window that is often open.
• Not on a dormer window or a roof above the living room or bedroom.

A complete heat pump makes a central heating boiler unnecessary. A hybrid heat pump works together with a central heating boiler.

A heat pump contains refrigerant. This substance is basically locked up in the heat pump, but sometimes a little escapes. The type of refrigerant in the heat pump makes a difference to the climate impact. Natural refrigerants have a much lower climate effect (greenhouse effect) than synthetic ones. Therefore, if possible, choose a natural refrigerant, such as propane.

If you choose a heat pump with an indoor and outdoor unit, it almost always contains a synthetic refrigerant. You also have a choice: for example, ask for refrigerant R32, which has a much smaller greenhouse effect than other synthetic refrigerants. Good to know: even with a synthetic refrigerant, a heat pump is better for the climate than a gas central heating boiler or an electric central heating boiler.

Heating at a lower temperature has an advantage: you have very even heat in your home. It does work a bit slower. You therefore have to heat your house a little differently than you are used to. With a fully electric heat pump, you set the thermostat at most 1 or 2 degrees lower at night than during the day. Because your house is well insulated (and it is, otherwise you wouldn't start with a fully electric heat pump), it doesn't lose that much heat at night.

In the morning, the heat pump can heat your house again easily and economically. If you set the thermostat much lower at night, the heat pump has to work much harder to heat the house again. This costs more energy, because the heat pump then has to work with a higher water temperature, which is much less efficient.

If you are going to be away from home for longer, for example on holiday in the winter, you can set it to 15 degrees. But keep in mind that warming up on your return will take a long time.

With a hybrid heat pump, the night temperature you set with the thermostat depends on the insulation of your home. Just like with a full heat pump, you can set the thermostat 1 or 2 degrees lower at night. Your house is then heated in the morning by the heat pump (not by the central heating boiler). If you set the thermostat lower by more degrees, heating up with the heat pump will take too long and the boiler will kick in. This usually has a greater climate effect than keeping warm with the heat pump. Exception: in poorly insulated homes it may sometimes be better to set the night temperature to 15 degrees. Your house is then heated in the morning by the central heating boiler instead of the heat pump, but that is sometimes more energy efficient than running a hybrid heat pump at higher night temperatures. So find a balance between the desired comfort and energy consumption. By heating up more slowly, you use the heat pump most efficiently (and use less gas). So also ensure better insulation, because then you get more out of your heat pump.

Keep track of how much power your heat pump uses and whether this is not more than previously calculated. You can sometimes do this with a simple plug that measures energy consumption or with an energy consumption manager with smart adapters. If you notice that the electric additional heat comes on often, you can ask the installer to determine the cause and take measures. With a hybrid heat pump, insight into its functioning is extra important: because the gas boiler can step in, any malfunctions are not so quickly noticed.

Have a heat pump maintained once every two years and it will last a long time (about 15 years).

Keep the outdoor unit clean and free of leaves. The air then flows properly and you have less chance of noise pollution.