Sizing an air-to-water heat pump (AHP) is an essential step in guaranteeing its efficiency and avoiding unnecessary costs. If the heat pump is too small, it won’t be able to meet your home’s heating and domestic hot water (DHW) needs, while one that’s too big will be too expensive and consume more energy. Here are the main criteria to take into account when sizing your heat pump.

Analyze heating requirements

The first factor to consider is the thermal load of your home. This is the amount of heat required to maintain a comfortable temperature inside, taking into account the outside temperature. To determine this load, you need to take several factors into account:

• Surface area to be heated: the larger the surface area, the more powerful the heat pump. This is measured in m² and calculated according to the average outside temperature in winter.
• Building insulation: a well-insulated house will need less heating, so a less powerful heat pump will suffice.
• The type of heating system: underfloor heating or low-temperature radiators are more compatible with an air-to-water heat pump, as these systems work better with lower water flow temperatures.
  

There are online calculation tools and professionals capable of carrying out this precise sizing, taking into account the specific features of your home.

Consider domestic hot water (DHW)

An air-to-water heat pump is also used to produce domestic hot water (DHW). Sizing should therefore also take into account DHW demand, especially if you have a large family. DHW requirements vary according to the number of people and daily use, for example for showers, baths and appliances. By estimating your daily requirements in liters, you can determine whether the heat pump should be adapted to meet these needs, or whether an additional hot water cylinder is required.

Calculate coefficient of performance (COP)

COP (Coefficient of Performance) is a key indicator of heat pump efficiency. It measures the amount of energy produced in relation to the energy consumed. A heat pump with a high COP is more efficient, as it produces more heat for less electricity consumed. It’s important to choose a heat pump with a COP adapted to the climatic conditions in your region, as the efficiency of the heat pump varies according to the outside temperature.

Take outdoor temperature into account

The performance of an air-to-water heat pump is influenced by the outside temperature. The lower the outside air temperature, the less efficient the heat pump will be. It is therefore essential to size the heat pump according to the minimum winter temperatures in your region. In colder regions, it may be necessary to opt for a higher-powered heat pump, or to provide additional heating (such as auxiliary heating).

Choosing heat pump capacity

The capacity of the air-to-water heat pump should be chosen on the basis of the results obtained using the above criteria. It is expressed in kilowatts (kW). The capacity required varies according to your home’s heating and DHW needs. A heat pump that’s too small won’t deliver enough heat, while one that’s too large will be less efficient, especially at low temperatures, and will consume more energy.

Conclusion

Sizing an air-to-water heat pump is crucial to maximizing its energy efficiency and guaranteeing optimum comfort. By taking into account heating and domestic hot water requirements, home insulation, climatic conditions and COP, you can choose the most suitable device. We strongly recommend that you call in a professional to carry out a precise calculation and avoid any unpleasant surprises. For further information or to obtain a quote, please contact us via our contact page, and visit our page dedicated to air-water heat pumps.