The most efficient way to run a heat pump

1. Adjust your heating curve
2. Keep your heat pump on for extended periods
3. Combine solar power, batteries and a time of use tariff
4. Upgrade your radiators
5. Optimise your Legionella protection
6. Deal with problems straight away
7. Bleed your ground loops (ground source heat pumps only)
8. Check your heating boost setting

This is also known as ‘outdoor weather compensation’. Your installer should set your heat pump’s heating curve when you first get it. If it’s not set correctly, it can increase your running costs. Let’s look at a heating curve in this graph. 

In the UK, we’re used to turning our heating systems on in the morning, off when we go to work and back on again in the evening when we return home. 

In Europe, however, they’re more likely to keep their heating on for longer. And instead of turning it off, they lower the temperature by a few degrees overnight or during the day when out at work. 

This is a good strategy for controlling heat pumps, which is known as a ‘set-back’.  

Make sure your heat pump isn’t trying to heat your hot water or the house overnight when outside air temperatures are significantly lower. That’s unless you’re using a time of use tariff when electricity is cheaper. 

During winter, the air temperature can drop by 5°C or more overnight. This will reduce the heat pump’s efficiency because it has to work harder to heat water to a high temperature. 

If the temperature of your home drops by a few degrees, your heat pump has to work a lot harder to warm it again. So, it’s best to keep your heat pump on all the time, and let your ‘set-back’ maintain a lower temperature when you’re out or asleep. 

You can maximise your savings and improve your carbon footprint even more by having your electricity come from a renewable energy source. 

Combining solar panels with a home battery lets you store free, renewable electricity to power your heat pump. This makes you less reliant on using electricity from the grid, bringing down your electricity bills further. 

The biggest benefit of a home battery comes in when you also have a time of use tariff. These tariffs encourage you to use your energy outside of peak times, with lower energy costs as a result. 

If you didn’t upgrade your radiators when you installed your heat pump, now’s the time to consider it. 

If the radiator in each room of your home isn’t big enough, that room won’t get warm. It doesn’t matter how big or powerful your heat pump is.  

Your radiators might have been fine when connected to a boiler, which typically runs at 75°C. But if the temperature of the water in the system drops to 45°C, which is usual in heat pumps, your radiators won’t be big enough. 

That’s if you continue to heat the house in the same way that you did with a boiler, like turning them on twice a day in the middle of winter.  

Larger radiators mean more surface area to circulate heat. And you can get radiators that don’t take up extra wall space. These are double or triple panel radiators. 

For more information on making your home fit for a heat pump, read our in-depth heat pump guide. 

UK building regulations advise that water cylinders (but not thermal stores) need to regularly reach temperatures of more than 60°C. This is to protect against Legionella bacteria, which causes Legionnaire’s disease. 

Your heat pump usually has this function to do this either daily, weekly, or permanently. If your bills are high, it may be because the timer has been set to do this job too frequently. 

For most, it’s safe to use this function weekly. If you’re at home regularly, you don’t need to do this every day.  

When your heat pump is installed, make sure you read your manual and understand the basics of both the control system and the heat pump itself.   

If there’s something critically wrong with the heat pump, the control screen will tell you.  

If you see warnings on the control screen, don’t ignore them. Check the fault log and see if you get recurring fault messages. Speak to the installer and manufacturer to find out what’s causing them. 

It’s better to fix these issues quickly and reduce the risk of your heat pump breaking down in winter. A common fault is a ‘heating blocked’ message, which might mean the heat pump is running at temperatures that are too high. 

Sometimes it’s a problem with the central heating system rather than the heat pump itself. Faulty pumps, valves or sludge and dirt in the radiators can all cause problems, which at first appear to an issue with the heat pump. 

If you don’t have water treatment and a filter in your central heating system, consider installing one as soon as possible. Not having these will cause long term problems with the heat pump, which could be expensive to fix.  

If you feel your installer isn’t taking your concerns seriously, speak to the manufacturer. They often have technicians who have more experience in at solving issues with your particular model.   

The ground loops in a ground source heat pump work just like in a radiator. Over time, air can get into the system and, if left unchecked, there might be occasional air locks that you need to bleed out. 

Your ground source heat pump may have a pressure gauge showing the pressure in the ground loops. Make a note of what pressure the installer set it to and make sure it doesn’t drop below this level too much.  

When you have a service, ask your technician for advice on how to spot potential issues and how to bleed your ground loops if they need it. For more information about what’s involved in a heat pump service, read our blog on common heat pump questions.

Heat pumps can perform down to -15°C or lower, but there may come a point when the heat pump’s output isn’t enough for you. However, there aren’t many days in a year when we see these sorts of temperatures. 

When temperatures plummet like this, the ‘heating boost’ or ‘heating comfort’ setting on your heat pump control panel can help. 

The heat pump uses an additional heater element to add energy to the system, until the temperature outside is within the expected limits. It’s quite normal for the heat pump to need a little help in the coldest periods. 

The heat pump doesn’t use this extra power for long, so it shouldn’t add much to your running costs, even over a whole year.  

Read your manual and make sure you have the heating boost set to come on only when the temperature outside is low enough. 

If you have to use this function regularly, speak to your installer as it might be a sign that: 

• your radiators are to small
• your heating curve isn’t set right

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