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What affects the efficiency of an air source heat pump?

Several things effect how efficient your heat pump will be:

• Temperature: The difference between the outdoor temperature and the flow temperature of the heat pump affects its efficiency. Essentially the colder it gets, the less efficient the heat pump is, but don’t worry all MSC-registered heat pumps are designed to be efficient in sub-zero climates and keep your home warm on the coldest days.  In fact, heat pumps can still work in temperatures down to -15. 

• Design: A properly sized heat pump will operate more efficiently. An undersized heat pump may not be able to keep up with the amount of heat the home loses (heat loss), while an oversized heat pump may turn on and off frequently, which decreases efficiency. It’s critical that your heat pump is designed properly to meet the needs of your property to ensure its sized correctly.

• Insulation: If your home is well-insulated, a heat pump doesn’t work as hard, as your property can retain its heat better. Proper insulation helps prevent heat loss through walls, roofs, and windows.

• Maintenance: Like any heating system, ensuring you keep up with maintenance and servicing ensures the heat pump operates at its optimal efficiency.

• Radiator size: The size and type of your radiators can affect efficiency. For example, bigger radiators are more efficient because the heat pump doesn’t have to operate at such a high temperature. Underfloor is also a great option due to its larger surface area. If you want to read more about radiators, this post goes into more detail. 

• Weather compensation: Getting the weather compensation right can help improve efficiency. Using an outdoor sensor your heat pump adjusts it’s settings to maximise the natural energy (heat) in the air.

• Hot water: Making sure the hot water isn’t set too hot can help improve efficiency. Most heat pumps are designed to emit hot water at temperatures between 45-50°C, which covers most needs (without burning yourself).

Will a heat pump cost me more to run?

Running costs can vary on several factors such as your energy tariff, and the performance of your heat pump.  With current electricity prices, the costs of running an air source heat pump will be similar to your average gas boiler unless you take out a heat pump specific tariff. However, if you’re replacing an older, G-rated gas boiler, you could save around £290 a year on your energy bills (6). 

There are also ways to save even more by switching to a heat pump tariff like the EDF Heat Pump and Save tracker(3) tariff which gives you zero standing charges for 12 months. You also pay less for running your air source heat pump at certain times.

How to improve heat pump efficiency

There are several things you can do to keep your air source heat pump running at maximum efficiency, including:

• Ensure your radiator thermostat valves (TRVs) are set to their highest setting.
• Make sure you bleed your radiators when you need to.
• Ensure weather compensation is set up correctly. 
• Leave your air source heat pump turned on all year round.
• Ensure your hot water schedules are set up correctly. 
• Keep windows closed on colder days (reducing heat loss).
• Don’t alter the settings of your air source heat pump without first consulting an expert.
• Look at dedicated energy tariffs which make running costs cheaper.
• Look into the benefits of solar panels to power your home and heat pump.
• Keep it clear from snow, debris, and obstruction, allowing for good airflow.  

Yes, your system may be less efficient in the winter, but it will still keep you cozy and warm. 

MCS requirements mean that all systems must be designed down to sub-zero temperatures which is more than adequate for the UK climate. Furthermore, each system is designed to keep your home warm in freezing temperatures.

If you live in a cold area and the temperatures drop below zero, you will see efficiency impacted but it certainly won’t leave you out in the cold. Most air source heat pumps are designed to work in temperatures of up to -15C.  The average UK temperature in the winter ranges from -2C to -7C so your heat pump will be more than able to cope with the UK climate and cold weather. 

It’s been written in the media and online that air source heat pumps are not suitable for the UK climate. This isn’t true.

An air source heat pump works by absorbing energy from the air outside and converting it to heat your home and hot water even in below-zero temperatures. There really shouldn’t be anything to worry about when the weather gets colder.

In the winter, your air source heat pump works no differently. Your heat pump is perfect for the UK climate because it can work off-grid and still operate when outside temperatures are as low as -15C. Even in freezing cold temperatures, air contains thermal energy and air source heat pumps absorb this heat and transfer it to your home using refrigerant. This will boil even in sub-zero temperatures.  Your air source heat pump works the same in winter as it does throughout the rest of the year, it will just work a little harder in the winter months in the same way that your old gas boiler did.  Your external unit is sealed and has been designed to withstand all the weather that the UK climate can throw at it.

A well-designed air source heat pump system, tailored to your property and local climate will keep you warm in winter, and provide you with all the hot water you need for many years to come.

Most of today’s heat pumps have a built-in defrosting and de-icing setting which keeps the fans clear so that your heat pump is always working when you need it. Never pour boiling water over your heat pump to defrost it. Your heat pump is an electrical appliance and doing so is highly dangerous and will damage your unit.

If you are impacted by snow, it never hurts to pop outside if you can, and make sure that the snow is away from the outside unit in much the same way as you would go out and keep your drive and paths clear from snow to access your house.

You could also consider a custom-built cover that has been specifically designed for your air source heat pump. We do not recommend making one yourself as you could block the airflow of the unit so have a chat with your installer about the options available to you.

Will a heat pump cost more to run in the winter?

Much like any heating system, your energy consumption will be more in colder months, due to outside temperature and the heat loss profile of your home (the rate in which your property loses heat).  An air source heat pump is like any other heating system in those colder months. As your home loses more heat, more heat is required to keep it warm.  

In winter you can expect your heat pump to use more energy (just like your existing boiler) and see an increase in your energy bill (depending on what kind of tariff you are on). The important thing to consider is that over the year, you would have still used 3x less energy than a boiler and saved some money too.  

Remember – Even if the savings on your energy bill are not enough to win you over, you are still reducing carbon and energy consumption, leaving a better world behind for future generations. Fitting your home with the latest technology can also increase its value. 

If you’re making the switch to an air source heat pump, you’ll be moving to a fossil-free system. Your air source heat pump will draw energy (heat) from the air around it.

When we talk about the energy used by an air source heat pump system, we’re talking about the energy required to operate it and extract the required heat from the air.  For Example – Heat pumps use 1kW of electricity and produce 3kw of heat. A household that uses 12,000kw of gas a year, will only need to use 4,000kw of electricity to produce the same amount of heat – that’s a huge saving on energy and carbon.  

Currently, electricity prices are higher than gas which means that the costs of running an air source heat pump will be similar to your average gas boiler. If you’re replacing an older, G-rated gas boiler, you could even save around £290 a year on your energy bills (6). 

However, there is a way to save even more. Switching to a heat pump tariff (like the EDF Heat pump tariff) means you pay less for running your heat pump at certain times reducing the cost of your electric bill.  With some clever scheduling of your hot water and smart meter, you can be money-savvy and save even more with your heat pump running costs.  

If you have solar panels, an air source heat pump could be the perfect choice. The power (electricity) that is produced can also be used to power your heat pump so you can reduce your energy bill even more. 

Every heat pump installation we carry out is specific to your home and your personal requirements. There are a wide range of factors that need to be taken into account before we can give you a dedicated quote. What we can say is that alongside the £7,500 Boiler Upgrade Scheme (BUS grant)(2) and any eligible finance options, a complete heat pump system, matched perfectly to your requirements as part of our bespoke system design service and fully installed, could be a lot closer than you think.

While the upfront costs may be higher than a gas boiler, air source heat pumps have a much longer life span and a much greater level of efficiency.  Running costs for a heat pump also vary and factors such as your energy tariff, type, and size of system are a few of the variables that impact running costs. The benefits of an air source heat pump system, and the savings it will ultimately generate, will far outweigh the initial outlay costs over time. We explore more about costs in our dedicated costs page.

We’ve been installing air source heat pumps for over 20 years now. Backed by EDF, we know we can create the perfect heat pump system for you.  What’s more, our systems are underpinned by the Heat Pump Promise. If your heat pump doesn’t work as promised, we’ll give you a refund.

So, if you’re just starting to look into the options, or have a few questions, drop us a message below and we’ll give you a call back.