Heat Pump

Yes, or no?


Let me cut this short for people with limited time... NO.

This emphatic statement is based on the fact that you probably have a gas boiler as the source of heat for your heating system. It’s NO - most definitely - NO. A heat pump will cost you more than your gas boiler, it’s as simple as that. Below I will show all the figures for that and why a heat pump doesn’t even stack up against an ELECTRIC heating system very well - and would take years to get your money back.


You’re probably reading this because Google or DuckDuckGO has led you here. You probably have got to the point where your heating source (boiler) needs replacing. Gas boilers last about 12.5 years[1] so replacement during your adult life may happen as many as 5 times! There is a concerted effort by the government to get you to have a heat pump. This is because they are stark raving mad - seriously. There is no climate crisis[2], and the campaign for Net Zero is just plain insane[3]. We (heating technicians) are being inundated through our trade magazines to sell heat pumps to our customers - our trade magazines have ceased to simply comment on what’s going on, and instead have joined the government’s campaign, with no alternative voices even heard.


We’re going to make assumptions during this explanation. Change assumptions and you change the calculations, obviously. Do so if you want to.


The first assumption we’ll make is that you have a central heating system (radiators) with a gas boiler as the heat source. This is the most common form of heating in the UK. For these calculations, we will look at gas, electric, and heat pumps. The electric heating system will be a simple one. We believe the ‘best’ heating system is a relatively expensive (to install) electric one. Not because of its 100% efficiency, but because of its simplicity and reliability.


So gas first:

A 3-bed home in the UK is going to consume 8,000 kWh a year for heating and 2,000 kWh a year for hot water. This then is a consumption of 10,000 kWh. But gas boilers are not 100% efficient, so in order to get your 10,000 kWh you will have to input 12,000 kWh for an 84% efficient gas boiler to give you 10,000 kWh a year...

12,000 x 10p = £1,200 (gas bill).



A simple electric system is 100% efficient. If you consume 10,000 kWh of electric at 34p per kWh then your consumption will be...

10,000 x 30p = £3,000 (electric bill)


Heat pump:

A heat pump uses electric, and heat from the air. Their efficiency is based on something called COP - coefficient of performance. This means (roughly) the energy you put in (electric) is converted to heat. So they can take electric input and magically enhance it by about 350%. This is a COP of 3.5. So you only need 3.5 of your electrical consumption. Remember your electric costs 34p per kWh...

10,000 kWh divided by 3.5 = £971 (electric bill)


So at first glance it would look like your heat pump is £229 cheaper every year...BUT...


Remember, we’re assuming that your gas boiler has come to the end of its life and needs replacing. Ok, so we’re going to assume a cost (which you hand to your heating technician) of £2,000 to replace your gas boiler. Over the course of the lifetime of a boiler, the replacement (saving up money to replace it every 12.5 years) is called depreciation. So your gas boiler depreciates at a cost to you of £160 a year.


To go all electric (a simple electric system) is much cheaper than the vast majority of people think. Small electric heaters are incredibly cheap and can be bought for just £15 each. However, we’re going to assume you want good control over them, so we’re going to guess £20 each x 10 = £200. Yes, really! An electric heating system really can be this cheap. We’re going to guess that one will fail per year, so that’s a depreciation cost of £20 a year.


A heat pump (to install) cannot just be thrown in as a replacement to your boiler. They operate at a lower temp than a gas boiler, typically. For this reason, you will have to have larger radiators. The cost of a heat pump can be just 50% more than replacing a gas boiler (at £3,000) but the other work required such as a cylinder for your hot water etc. bumps that up to around £14,000 typically. Heat pumps depreciate at the same rate as gas boilers, and have to be replaced. Assuming a replacement cost of £4,000 it means an annual depreciation of £320 a year (your cylinder will also depreciate!).


So already we see huge variances in replacement costs. Although an electric system is expensive to run, it is cheap to install and maintain. Although a heat pump is expensive to install, it is cheap to run. And gas falls between the two. There are though, other factors to take into account before we come to some conclusion.


Gas boilers do break down - they need maintenance and servicing. This then is an annual cost you MUST take into account to get a real grasp of how much your boiler actually costs you. We’re going to assume an annual cost of £200[4]. This then, together with the cost of gas used and depreciation takes the overall annual cost of your gas boiler to...



Electric systems tend to be very reliable, as usually they just have an element. We have already assumed a heater replacement annually, and they require no maintenance, so together with the cost of electric used, the overall annual cost of your electric heating system is...



Heat pumps are a rather unknown kettle of fish! They haven’t really been in long enough for us to get a grasp of reliability, and the costs of calling out technicians to repair them. Much guessing is currently being done, but it’s thought that they are roughly double the cost of a gas boiler to maintain, so £400 a year[4]. So together with the cost of electric used, the overall annual cost of your heat pump is...



So a heat pump will cost you £131 MORE than a gas boiler every year. And let’s not forget that you have invested £12,000 more (for your heat pump) than you would for replacing your gas boiler. So when people talk of how long it will take to get your investment back in saved energy, the answer is you don’t get your money back. The whole experience is a COST to you, NOT a saving. Even against an electric system, a heat pump is ‘only’ £1,329 cheaper a year. Over 20 years, your saving (against electric) would be considerable. But due to the high cost of the investment needed for a heat pump (£14,000) it still means that it would take you 10 years to pay your investment back - even against an electric system!!!


And there’s lots of talk from people on YouTube about how the cost of installing heat pumps will come down. No, they won’t! Specialist engineers will RAISE their prices, not drop them, and although the purchase cost of a heat pump may drop a little, it’s not going to be much less than the £3,000 we have assumed here, if at all.


So we’ve made a few assumptions here which you may question. If so, input your own figures where we have put ours. You will still find that a gas boiler is cheaper than a heat pump when everything is taken into account, and that you will NEVER get your money back in savings. Remember, the government don’t want you to have a heat pump in order to save you money, they want to (insanely) drop CO2 emissions (and gas boilers emit CO2), so they may well lie and say that a heat pump will be cheaper than your gas boiler. IT WON’T.


Typical energy consumption per year (assumed) of a typical 3 bed home:

Heating 8000 kWh

Hot water 2000 kWh

Total 10,000 kWh

Other (lighting, cooking) 3000 kWh


Finally, we’re going to do a little calculation to show just how poor heat pumps stack up even against electricity...

Imagine you want a heat pump to provide your hot water demands (just that, you’re happy with your heating - perhaps a wood burner). So, we’ve already said that your hot water demand is 2,000 kWh a year. If you use an immersion heater to provide that, it will cost you £680 a year. You would now have to find a heat pump which is so inexpensive to buy, install, and maintain, that you would get your money back in say 10 years. Remember, you aren’t going to get free electricity - your heat pump will still cost you £194 (at a COP of 3.5) in electricity, so your actual saving is £486 a year. So that would be a heat pump costing around £3,360 to buy and install (we’re adding another £1,500 over those 10 years for maintenance, so £4,860 in total). Can you get a heat pump purchased and installed for £3,360? And remember, that’s against electric! The £2,995 quoted by British Gas may include everything, I don’t know. If so, that would be viable...but it would still take you 10 years to get your money back - even against electric.



[1] Defra figures

[2] Not a single scientist anywhere says there is a climate crisis

[3] Why It Won’t Ever Happen

[4] Over the lifetime of an appliance - call-out costs, parts, and servicing