The bigger the heat pump, the better… right? Not quite. When it comes to determining the right size heat pump for your home, there is little room for error: if it is too large, the heat pump will run too short; if it is too small, the system will die too oftenUse additional heating. In both cases, the result is an inefficient and expensive heating system. To correctly size an air-to-water heat pump, you need an experienced and certified heat pump installer with special design software. Most poorly functioning heat pumps are due to a lack of knowledge of this software. Since this seems to happen all too often, we've put together a quick heat pump sizing guide to help you find the right size for your home.
Air-water heat pump – intelligent and economical energy generation
The air-water heat pump is called the heat pump of the future because it is robust, simple, space-saving,efficient and environmentally friendlyis. It uses the outside air heated by the sun to generate hot water and warm heating air. Modern systems can draw enough energy for heating even from cold winter air. This heating system also has the advantage of emitting less CO₂ and consuming very little energy. You can find out how much electricity an air-water heat pump needs in this guideCosts and efficiency of the heat pumpexperience.
Sizing a heat pump
Heat pump sizes range from around 3kW to 15kW and are typically quoted at industry standard temperatures, i.e. 7°C/35°C. This means that a 10 kW air heat pump achieves its output of 10 kW at an outside temperature of 7 degrees and a flow temperature of 35 degrees. As a rule of thumb, a well-insulated house requires 1 kilowatt of heat per 25 m² of living space, while the same power only heats 10 m² in a poorly insulated house.
A heat pump with an output of between 4 kW and 12 kW is usually more than sufficient for most single-family homes in Germany with good insulation. For large, poorly insulated houses, heat pumps with an output of 15 kW and 16 kW are the better choice.
The size of heat pump you need for your home depends primarily on three factors:
- Design temperature
- Desired room temperature
- flow temperature
Design temperature
The heat extracted from the outside air is absorbed in the evaporator and transferred to the low-pressure refrigerant. In order for the refrigerant to start boiling, the temperature of the environment must be higher than the temperature of the refrigerant. The warmer the outside temperature is, the better the heat pump works.
To ensure the heat pump can meet your home's heating needs year-round, heat pumps are sized based on the coldest air temperatures of the year in your area.
The design temperature for your area is determined from theTaken from climate database– the lower the coldest temperature, the larger your heat pump needs to be. In Germany, for example, the minimum outside temperature is usually between -12 °C and -16 °C. But in Passau, for example, the climate is moderately warm and the outside temperature does not drop below -5 °C.
The only downside is that theHeat pump for your heating needsis technically oversized if the outside temperature is above this “worst case” temperature. Another factor that plays a role in the precise design is the wind chill effect, which takes into account the difference between the measured and the perceived temperature as well as the wind speed. It depends on how protected or exposed your house is.
Desired room temperature
The desired room temperature is determined by the homeowners. As a rule, most people want a warm and comfortable room temperature of 21°C. However, at lower room temperatures there is less heating required, so a smaller heat pump can be used in your home. The lower the room temperature, the better.
The difference between the outside and inside temperatures can be used to determine the total heat loss of a property.
flow temperature
The flow temperature is simply the temperature at which the water must circulate around the radiators in your home to reach the desired room temperature.
This depends on the size of the radiators (and underfloor heating if present) and theInsulation of the houseaway. If the radiators are too small, the flow temperature must be higher to achieve the desired room temperature. The better the insulation, the slower the heat can escape to the outside and the less heating needs to be done to reach the desired room temperature.
