If you’ve got a heat pump and your electricity usage seems higher than you expected, you’re probably wondering whether that’s normal or whether something isn’t quite right.
The first thing to say is that there isn’t a single amount of electricity a heat pump should use. Every home is different, and how much electricity your heat pump uses depends on things like the size and heat loss of your home, the weather, how warm you keep it, how much hot water you use and how efficiently the system is running.
So seeing your electricity usage go up doesn’t automatically mean there’s a problem.
However, if your electricity consumption seems unusually high, has suddenly increased or you’re struggling to keep the house warm, it’s worth finding out why.
Here’s what to look at.
Have there been any changes in your household?
Before changing anything, it’s worth taking a step back and looking at what has changed.
Your heat pump will naturally use more electricity when your home needs more heat. If you’ve gone from mild autumn weather to a cold spell in winter, for example, your heating demand will increase.
The same applies if you’ve:
- Increased the temperature you want your home to be
- Started heating more rooms
- Had more people living in the house
- Started using more hot water
- Had colder weather than usual
- Changed how you use the heating
It’s also worth remembering that your heat pump uses electricity for both heating and hot water. If you’re looking at your total electricity bill, there will be other things contributing to it as well.
So don’t assume that a bigger electricity bill means the heat pump itself is inefficient.
The more useful question is:
Is my heat pump using more electricity than you’d reasonably expect for my home and the conditions it’s working in?
That’s where things get more interesting.
Cold weather can make a big difference
Heat pumps don’t work at a fixed level all year round.
When it’s cold outside, your home loses heat more quickly. Your heat pump then has to put more heat into the house to keep it at the temperature you’ve asked for.
There’s another factor too.
A heat pump works by moving heat from outside into your home. The colder it is outside, the harder the system has to work to lift that heat to the temperature needed by your heating system.
This affects its coefficient of performance (COP), essentially, how much heat the heat pump produces for each unit of electricity it uses.
As the outside temperature drops, the heat pump generally becomes less efficient, so it can use more electricity to provide the same amount of heat.
So don’t judge your heat pump’s performance based on one particularly cold day.
A better way to spot a problem is to look at your electricity use over a longer period and compare it with what was happening in the house and outside.
Your home has a bigger impact than you might think
Two houses can have the same heat pump and completely different electricity consumption.
The reason is simple: the heat pump is replacing the heat your house is losing.
A large, poorly insulated house will generally need more heat than a smaller, well-insulated one.
Things that can make a difference include:
- The size of the property
- Loft, wall and floor insulation
- Windows and doors
- Draughts
- The temperature you keep your home at
- How many rooms you’re heating
- How exposed the property is
This is why comparing your electricity usage with a neighbour’s isn’t particularly useful unless the houses and how they’re being heated are reasonably similar.
If your home loses a lot of heat, the heat pump has to replace that heat. Improving the fabric of the building can therefore reduce the amount of heat the system needs to provide.
The way your heat pump is working matters too
The amount of electricity your heat pump uses isn’t just about the weather or the size of your house.
The way the system has been designed, installed and set up can make a difference too.
One important factor is the temperature the heat pump needs to produce for your heating system.
In general, a heat pump works more efficiently when it can heat your home using a lower flow temperature. The lower the temperature it needs to produce, the less work it generally has to do.
That doesn’t mean you should simply turn the flow temperature down as far as possible.
Your heat pump still needs to be able to provide enough heat to keep your home comfortable. If it needs to run at a much higher temperature than expected, there may be a reason for it.
If you want to understand your heat pump settings in more detail, we’ve covered that separately in our guide to reducing your bills while keeping your home warm.
Don’t forget about hot water
Your heat pump isn’t only heating your radiators.
It’s also heating your hot water, and that can make up a noticeable part of your electricity use.
The amount of hot water your household uses will obviously affect this. A family taking several showers a day will have a very different demand from someone living alone.
Your hot water cylinder also needs to reach a higher temperature than your heating system normally operates at. This means the heat pump can use more electricity when heating your hot water than it does when providing space heating.
So if you’re looking at your electricity consumption and wondering where it’s all going, don’t forget to consider hot water.
When could high electricity use indicate a problem?
This is the important bit.
Higher electricity consumption doesn’t automatically mean your heat pump has a fault. But there are situations where it’s worth getting the system checked.
For example, you may want to investigate further if:
- Your electricity consumption has suddenly increased without an obvious change in weather or how you use the house.
- The heat pump is running for long periods but your home still isn’t reaching the temperature you want.
- You’re having to keep increasing the heating temperature to stay comfortable.
- Your system is regularly using an additional or backup heater.
- You’re seeing error messages or fault codes.
- Your hot water isn’t reaching the temperature you expect.
- The heat pump is making noises that are unusual for your system.
- The outdoor unit is repeatedly becoming heavily iced up.
- You’ve recently had work carried out on the heating system and your electricity use has changed noticeably.
None of these things automatically means there’s a fault with your heat pump. But if you’re seeing one or more of these signs, it’s worth getting an engineer out to have a proper look at the system.
They can check how the heat pump is operating, look for any faults or issues with the wider heating system, and help work out whether there’s a genuine problem behind the higher electricity use.
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