WHAT SIZE HEAT PUMP DO I NEED?

Getting your heat pump size right isn't just a simple equation. Here's everything your installer will need to take into account

- DAVID HILTON Is an expert in energy efficiency and director of Heat & Energy Ltd.

Heat pumps and heat pump technology are no longer new, and in fact most of us have had one in our homes for many years in the form of a fridge.

They operate on the same principle, using a refrigerant-based system to heat and cool.

However, in the same way as you wouldn't expect a small fridge to provide enough space for a large family's food, or to work hard enough to freeze the food, heat pumps also need to be designed to be able to heat your home efficiently.

Getting it wrong can result in increased costs - both in terms of energy usage and in the risk of paying too much for an over- or undersized system. Calculating the final heat pump size should always be done by a qualified installer, but here's what they'll be taking into account when they determine the right heat pump size for your home.

SIZE IS IMPORTANT

Traditional central heating systems often had boilers that were actually too big. This was especially true for combination boilers, which needed to be big and have a higher flow rate in order to meet the hot water needs of showers and baths. However, this meant the energy efficiency of the heating was compromised, as the boiler would constantly switch off and on again in short cycles to heat the home. Modern boilers can modulate this more, but sometimes not enough to prevent the stop-start cycles.

Heat pumps, however, need attention when it comes to specifying the size, which is why there are a number of considerations to take into account when sizing one, as I explain in more detail below.