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What Does the COP Rating of a Heat Pump Mean?

The Coefficient of Performance (COP) indicates the efficiency of a heat pump. For example an heat pump operating at a COP of 3 would provide 3kWh of heat for every 1kWh of electricity consumed. Higher COPs indicate higher energy efficiency levels.

How Much Electricity Does a Heat Pump Use?

The average home requires around 12,000 kilowatt hours (Kwh) of heat per year. In order to achieve this, a heat pump boiler with a COP of 3 would use 4,000kWh of electricity annually (12/3=4). This figure will depend on the size of your home, how well insulated it is and how much hot water you use. It will also depend on the efficiency of your heat pump. 

How Much Does an Air Source Heat Pump Cost to Run?

A simple calculation can provide you with a rough idea of how much a heat pump could cost you per year to run. Take your annual heat demand and divide by the COP rating of your heat pump to work out how many kWh of electricity your heat pump will use annually. Then use your final kWh figure and times by what your supplier charges you for electricity per unit. So, as an example, 4000kWH of electricity priced at £0.28 a unit will cost you around £1120 per annum in heating costs 

An example equation looks like this: 12,000kWh (annual heat demand) / 3kW (heat production per unit of electricity) = 4,000kWh of electricity  

If you're struggling to work out your annual costs, Great Home provide a simple online calculator for working out Air Source Heat Pump running costs

What Size Heat Pump Do I Need?

In terms of output, this depends on the size and type of your home, i.e whether you live in a bungalow or terraced house, a two-bedroom property or a 5-bedroom property. Generally speaking, a heat pump with an output rating between 5kW and 12kW should be adequate for most UK homes. As a rough guide, most installers will recommend 1kW of output for every 10 square meters, however this does depend on how well insulated your home is.

If you're trying to work out what size hot water cylinder you need than it is important to ensure it will meet the demands of the household. As a rough guide it is recommended that a 180L cylinder is appropriate for a two bedroom house, a 210L cylinder for a three bedroom house and a 250-300L cylinder for a four bedroom property.


We hope that this guide has helped to answer your questions about hot water heat pumps. We've also written another handy guide which covers questions about how heat pumps work, how to install them and where to buy a heat pump from. However, if you still have questions please contact a member of our knowledgable team on 0203 994 5470, drop us an email at sales@electricpoint.com or use our Contact Form.