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When to consider using an air source heat pump

Posted by John Lightfoot on 8 December 2010 at 2:07 pm

Air source heat pumps can be used in many applications for heating water, be it domestic (tap) water or the water used in for space heating.

The first part of the decision process of whether I should consider using an air source heat pump to heat my house starts with – "why I am doing this?".

Heating System

There are of course a multitude of reasons one might consider a heat pump: your existing heating system is on its last legs; you want your next heating system to be more environmentally friendly; or you currently use a heating system where fuel cost are prohibitive and so you are on a quest to find a cheaper running cost option.

Running costs

If you are looking to replace a modern condensing gas boiler then the payback period will probably not encourage you to make the switch to a heat pump. If, however, it is any other fuel type, (with the exception of free biomass of course!) there may be considerable running cost savings to be made.

The most obvious savings can be seen when comparing heat pumps to direct electric heating or storage heaters where the 3 to 1 coefficient of Performance (COP) provides the obvious economies (see my previous blog, An introduction to air source heat pumps).

It is, however, probably fair to say that compared with all other traditional fuel heating technologies (with the exception of mains gas and free biomass) considerable running cost savings can be made. This is in addition to the ease and convenience of use of heat pumps.

Air source heat pumps can be controlled like a gas fired heating system with programmable timers and room thermostats or thermostatic radiator valves. It beats having to stoke up the fire or having to store heat the previous day because it was cold and then having to allow it to escape by opening the windows the following day in this wonderful changeable climate we have in the UK.

Carbon savings

If the reason you’re looking to replace your existing heating system is to reduce your carbon footprint to help protect your grandchildren’s future environment, then heat pumps stack up well against most traditional heating technologies. Savings of over 1 tonne of CO2 per dwelling per year can be made even against mains gas systems, perhaps the cleanest of all of the traditional fuel technologies. As our national grid becomes cleaner then this figure will only improve.


Life is never simple of course. There are some issues that prevent an air source heat pump being your best option even if you are not in a mains gas area and I will discuss these in my next blog “Where you can use air source heat pumps".

Picture by Andrew Magill

About the author: John Lightfoot is director at Thermal Energy Ventures Ltd.

If you have a question about anything in the above blog, please ask it in the comments section below.

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3 comments - read them below or add one


FarrellMackennonComment left on: 28 January 2014 at 7:54 am

Air source heat pumps aren’t suitable for every house and I can’t count the number of times I have had to point this out to home-owners who want advice on switching their current heating systems for something cheaper or more environmentally-friendly. They’re not that cheap to buy either and there are a variety of conditions to be followed if they are to be fitted correctly. Always get an experienced plumbing company to come and do the work for you as then the work is under guarantee and you can call them back if there are any problems.

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Mike Maybury

Mike MayburyComment left on: 20 December 2010 at 6:01 pm

Will one be permitted to have a cheap night time tariff for the electric supply with a heat pump? I can see that savings in running cost might be considerable ie. 3 by 3. A very large storage tank would be a one off expense, which would probably last forever.

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Stirling Consulting Limited

Stirling Consulting LimitedComment left on: 14 December 2010 at 4:33 pm

As per my last responses it would be good if you took the time to declare the MANDATORY considerations when discussing the fitment of these units. Equally with the lower flow temperatures a typical family of four might find the response time lacking against that of the boiler- which may not be a problem but should be stated in the pre-amble?

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