Do heat pumps work with radiators? Your questions answered

Speak to an expert – Get a free quote

Updated: 4th August 2025

Can I use my existing radiators for my new heat pump?

Yes, you can but there are some caveats. Many people worry about needing to upgrade their radiators when switching to an air source heat pump. Sometimes, this concern puts people off the idea entirely – but it doesn’t have to!

If your radiators are not old, 30+ year models, you may not need to upgrade them. An air source heat pump system can still work with newer radiators. It just may work less efficiently than it otherwise would.

Even with old panel radiators, the heat pump system will still work. However, it may be too expensive to run. Therefore, while it is possible to use existing radiators, upgrading them can enhance efficiency and reduce running costs significantly.

To summarise: 

• Look for radiators with the largest surface area possible for each room in the house.
• Try and steer clear of designer radiators or small radiators in large rooms which won’t give you the heat output you need.
• The larger the surface area of your radiator, the more efficient your new air source heat pump system will be.  

We can always help point you in the right direction if you need advice.

Will radiator upgrades reduce costs?

Upgrading the radiators in your home can make your heating system more efficient. This can lower your energy bills and improve your comfort.

If efficiency and running costs matter to you, check the type of radiators you have. Count how many there are. Also, see if you need to upgrade any before installing your heat pump. Remember, you should have a more efficient system. This can lower your energy bills and improve comfort in your home.

If you can’t afford the extra cost of upgrading radiators right now, you might choose a higher flow temperature system. To find out more, speak to one of our experts who will advise on the best way to proceed.

Why you should consider upgrading your radiators as part of your heat pump installation

If we think upgrading your radiators will help you, we will guide you on what to do next.

1. Effective system planning

Our system designers will effectively plan the system output and operational efficiency for you. We will pair a suitable heat pump and any radiators for your home. This will result in a much more efficient system.

Effective project management

Radiator replacements may add to the overall time that an installer has to be present. Installing them in the same project helps the engineer plan the time needed to finish the job quickly. It also removes the need for a separate engineer later. They would need extra time to learn your home’s system.

3. Lower operational cost

Getting the maximum efficiency possible out of your heat pump system is a key part of our offer. Over the whole year this means you could save significant amounts on your energy bills. 

You can save money by replacing an old G-rated gas boiler. If you keep the same energy plan, you might save up to £290 a year on your energy bills.* For more information on what affects heat pump efficiency, read our dedicated efficiency page here.

4. Finance plans available

If approved by our lending partner, you can split the cost of your heat pump investment into monthly repayments over a number of years. And this includes the whole system upgrade. This financing can include the cost of radiator upgrades, allowing you to manage payments more easily.

Identifying what radiators I have

To ensure you have the right radiators for your heat pump, it’s crucial to identify the type you currently have. Here’s a guide to help you:

• Single panel radiators: One flat panel, usually slim and lightweight.
• Double panel radiators: Two flat panels, back-to-back, thicker than single panel radiators.
• Radiators with convectors: Panels with zig-zag metal fins (convectors) between them.
• Triple panel radiators: Three panels, very thick, and heavy.

The best radiators for air source heat pumps

The best radiators for air source heat pumps are those which have a larger surface area.

Why? Well air source heat pumps operate at a lower temperature to traditional gas boilers. Typically you’d want radiators that are 2.5 times the size of standard radiators. For example radiators which are double or triple panelled work very well. Radiators with smaller surface areas often operate less efficiently than those with larger surfaces. Therefore, upgrading to a larger radiator is a crucial consideration.

We can advise you on the best course of action and we have a handy table explaining which radiators work best below.

Below is a breakdown of different types of radiators and their implications:

Radiator type: Type 44

K naming convention: K4

Configuration
(panels and convectors):
4 panels, 4 convectors

Heat output: Extremely high

Suitabiity with ASHP:
Extremely suitable, best for ASHP

Underfloor heating

If you have underfloor heating, this will work alongside air source heat pump. We will need to understand the output (kw) to design a system for you. Spacings of underfloor heating pipework and bore size are key to making this work. 

If you don’t have underfloor heating, remember that adding this system later can be costly.

Size matters

The larger the radiator, the better it will perform with a heat pump. Heat pumps work at lower temperatures than traditional boilers. Larger radiators release heat better at these lower temperatures.

Radiator types to avoid

Aluminium radiators: Conduct heat more efficiently but can also cool down much quicker. They are also more expensive than traditional radiators.

Designer radiators: They often focus on looks instead of function. This can lead to not enough surface area for good heat transfer in a heat pump system.

Towel rails: Typically designed for supplemental heating in bathrooms, not for primary heating, resulting in poor performance.

Cast iron radiators: They hold heat well, but they take a long time to warm up. They are not good for the lower temperatures that heat pumps use.

What if I have one of these radiators?

This does not necessarily mean they won’t meet the heat loss of the room, or work with an Air Source Heat Pump system. Our design team will check the output and flow temperatures of your current radiators. We will advise you on whether we think it is possible to keep them or if we recommend replacing them.

To summarise

Here’s what to consider when thinking about your radiators

• H3 Surface area – The surface area of your radiator should be as large as possible. This helps provide the heat you need and the efficiency you want.
• H3 Flow temperature – The lower the flow temp = the larger the radiator = the more efficient your system will be.
• H3 Material of radiators – In reality, there is no ‘best material’ for radiators to work alongside your heat pump. Surface area is far more important.

So, do I need to upgrade my radiators or not?

Once you have considered the above, you have three options:

1. Use your current radiators – If your radiators can work with your heat pump, you can still proceed. If not, you can choose to have a high temperature heat pump installed to compensate for your radiators. These heat pump systems are more expensive.
2. Upgrade your radiators when you install your air source heat pump. If your radiators are old or not working well, it’s a good time to replace them.
3. Update your radiators later – If you set your heat pump to a higher flow temperature, then you may not have to upgrade your radiators. However, this will make your system more expensive to run. The lower the flow temperature = the larger the radiator = the more efficient your system will be.

Ultimately the choice is yours. In some cases, there is no need to upgrade your radiators when installing your new air source heat pump. Many customers choose to upgrade their radiators. This helps them get the best efficiency from their heat pumps. We are always happy to advise you on the best course of action whatever you decide.