Heat pumps come in a variety of sizes, ranging from around 6kW up to 15kW. You don’t want to get the wrong sized heat pump, as it will impact the return on your investment and should be calculated by a trusted installer. A heat pump that’s the correct size should heat your home adequately all year round. If your heat pump’s output is too low, it will have to run for longer, and if it’s too powerful for your house it could short cycle, where it turns off, which is bad for the motor and means it won’t perform efficiently.
According to Evergreen Energy, a well-insulated house requires 1 kilowatt of heat for every 25 square metres of space, whereas in a poorly-insulated house, 1 kilowatt of heat will heat 10 square metres.
To make sure you get the correct size the following should be considered:
The size of your home - in general, the bigger the house the bigger the heat pump, but you should also consider the layout of your home. Is it a bungalow or a townhouse? If you have a large lounge, this is typically heated for longer and to a higher temperature than a bedroom.
The level of insulation in your home - to make the most of your heat pump you should make sure your house is well insulated. An Energy Performance Certificate (EPC) will show any structural factors that should be addressed before the installation to make sure you’re not losing heat unnecessarily.
Your location - the temperature range in your local area should be taken into consideration when designing your heat pump. The warmer your area, the smaller your heat pump should be. The heat pump should be sized on the coldest average temperatures for your area. The Microgeneration Certification Scheme (MCS) will provide data on this.
Your existing heating system - a new heat pump needs to work with your current heat distribution (or you could look at upgrading or replacing your current one). Heat pumps work well with underfloor heating, as they provide hot water at a lower temperature than boilers. Radiators need a more powerful output to reach the same room temperature. This means that a larger surface area is needed for the heat to be emitted at the same level of comfort. The size of your radiators and your ideal temperature would also affect the size of your heat pump.
Rough guide of size installations by Boiler Guide:
This is something that you don’t want to get wrong, as it will impact the return on your investment and should be calculated by a trusted installer. We’ll be writing more about trusted installers soon.
I hope this was helpful, what other content on heat pumps would you like to see?