When considering the benefits of air-source heat pumps (ASHPs) over gas or oil boilers, one aspect...
Brass tacks: How much does each heating system cost to run?
It’s probably not too far from the truth to say that whatever the various benefits of heat pumps vs. boilers are, the thing that most people care about is the cost of running their heating system!
So how does the cost of running a heat pump work out against three common alternatives?
It’s all about the efficiency
The cost of running your heating system is determined by the relationship between two key numbers.
One is the price of fuel - whether it’s gas, oil or electricity.
The other is the efficiency of the system. This is a measure of how well the system can turn a unit of fuel into a unit of heat. Let’s talk about this first.
As an example of how different levels of efficiency can have an impact - imagine boiling some water in a saucepan. In one scenario we’re holding the saucepan over a gas hob, and in another we’ve placed it on an induction hob.
Gas hobs look like they’re doing a good job, with a nice solid blue flame and the feeling of the heat coming off them - but all that energy converted to light, or radiated out as heat you can feel, isn’t going into the water! A common estimate is that gas hobs are turning only 45% of the energy put into them into heat that’s actually applied to your food. The rest of it is lost to the air.
Induction hobs work differently. They use magnetic induction to heat the pan directly, meaning around 90% of the energy that goes into them is applied to food as heat! The other 10% is either lost in generating the magnetic field, or radiated by the hot cookware back to the cooking surface.
Compare the two then, and induction hobs are a much more efficient way of heating that water up, using twice as much of the energy that you put in for the purpose it’s intended.
And when it comes to efficiency, not all heating systems are born equal.
Lets see the numbers
| Combi Boiler | Oil Boiler | Electric Radiators | Air Source Heat Pump |
| Gas boilers - and combi gas boilers - are about 85% efficient | Domestic oil boilers are about 85% efficient | Electric radiators are 100% efficient | Air source heat pumps are anywhere between 280% and 450% efficient. |
From that table alone it looks like direct electric radiators - which operate at 100% efficiency - are a better option than gas or oil boilers. But we’re missing the crucial second element here, which is the cost of fuel.
The high price of UK electricity
Recent reporting has highlighted that the UK has the highest electricity prices in the world; twice the median price of electricity paid by the 34 members of the International Energy Agency. This inflated electricity price can mean that running direct electric radiators becomes prohibitively expensive, even though they’re at 100% efficiency.
Let’s take a look at the numbers, assuming that the average home needs 14,000 kWh of heat over a year.
| Gas Boilers | Oil Boilers | Electric Radiators | Air Source Heat Pumps | |
| Efficiency | 85% | 85% | 100% | 350% |
| Fuel Type | Gas | Oil | Electricity | Electricity |
| Units of fuel needed a year | 16,470 | 16,470 | 14,000 | 4,000 |
| Cost of fuel type | 10p per kWh | 10p per kWh | 35p per kWh | 35p per kWh |
| Cost of heating | £1,460 | £1,460 | £4,900 |
£1,400 |
We can see that even though heat pumps and electric radiators are both powered by the same fuel at the same cost, the dramatic difference in efficiency between them means running a heat pump is thousands of pounds cheaper per year.
That cost of running a heat pump can be lowered even further if the homeowner switches to one of the new heat pump specific electric tariffs, provided by energy suppliers like Ovo, and Octopus.
These tariffs lower the cost of energy used by the heat pump down to 15p per kWh, making running a heat pump significantly cheaper! Here’s that same table with the heat pump on a specialised tariff.
| Gas Boilers | Oil Boilers | Electric Radiators | Air Source Heat Pumps | |
| Efficiency | 85% | 85% | 100% | 350% |
| Fuel Type | Gas | Oil | Electricity | Electricity |
| Units of fuel needed a year | 16,470 | 16,470 | 14,000 | 4,000 |
| Cost of fuel type | 10p per kWh | 10p per kWh | 35p per kWh | 15p per kWh |
| Cost of heating | £1,460 | £1,460 | £4,900 | £600 |
The importance of a good installation
The efficiency of a heat pump is determined by the quality of installation! It’s crucial to get a system designed by an expert engineer, and installed to the highest quality standards. Partnering with Fornax can help you with this, as with our network of vetted, expert engineer partners we’re perfectly placed to help you upgrade your heating system while downgrading your bills!
If you'd like to talk to us about what a heat pump installation can do for your bills, feel free to pop in your details below, and one of our heat pump enthusiast team will give you a ring!
