Heat Pump Running Costs

Every customer wants to know how much cheaper a heat pump is to run than a gas boiler. The mainstream and social media are full of misinformation on this topic so it’s important to layout the facts clearly and honestly. It’s also vital that customers have realistic expectations and an understanding of how they can influence the outcomes.

A few basics…
A heat pump is extremely efficient.  For instance, a Samsung EHS R290 can be more than 400% efficient over the course of the year.  An old gas boiler on the other hand is more likely to be around 85% efficient.

So a heat pump must cost hardly anything to run compared to a gas boiler, right? WRONG.

That’s not the whole story, while the heat pump efficiency is magnificent, electricity is more expensive per unit of energy than gas, at the time of writing this article, a standard electricity tariff was 25.55p/kWh and gas is 6.14p/kwh.
That’s 4 times the price.

So how does this stack up in real life and what are the comparable running costs?

Tariffs

For starters, you need to sort out the right tariff.  There are many heat pump tariffs now available which give cheaper power periodically throughout the day.  This cuts the normal running costs.  For instance, EDF have a tariff that reduces the rate by 10p/unit for 6 hours per day.

Flow temperature next
The next thing to consider is the flow temperatures, with a 55 degree flow temperature (the maximum allowed under the £7500 boiler upgrade scheme grant) you won’t need to change many radiators but the seasonal efficiency isn’t the highest (for Samsung R290, its around 340%).  With a lower flow temperature, perhaps 45 degrees, the radiators need to be larger but the efficiency improves (more than 404% efficient).  These efficiencies are based on weather compensation so the heat pump only runs at this highest flow temperature when it is coldest outside.

The bottom line

• Heat Pump at 45 degree seasonal flow is likely to save about 40% vs a mains gas boiler
• Heat Pump at 55 degree seasonal flow is likely to save about 25% vs a mains gas boiler

These figures are based on a heat pump tariff (with some load shifting) vs an 85% efficient gas boiler.

What’s next?
We expect over the coming months and years to see more pressure from the government on reducing the cost of electricity for heat pump owners.  We also expect to see the £7500 boiler upgrade scheme (BUS) grant reduce or disappear.  So now is a good time to get a heat pump fitted.

It’s also worth noting that the Samsung EHS R290 is a particular efficient heat pump, many heat pumps do not operate at the kind efficiencies outlined in this article.  Quality of installation is also a vital factor in determining system performance.