<span class="article__meta">Written by</span><p class="author__name"><a href="https://www.cbheating.co.uk/author/james-enderby/" target="_self">James Enderby</a></p>

James Enderby

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Jamie Ansell

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Do you need new radiators for air source heat pumps?

Many customers reach out to us concerned about having to upgrade their radiators when considering making the jump to an air source heat pump. Sometimes, in fact, this puts them off the idea entirely – but it doesn’t have to!

Here’s what you need to know if you’re concerned.

You don’t need to upgrade your radiators

Firstly, let’s be clear from the outset. 

Unless your radiators are conventional-type, 30+ year-old models, you don’t need to upgrade your radiators for an air source heat pump system to work, it just may work less efficiently than it otherwise would.

Even with these outdated panel radiators, the heat pump system will still operate, but may be unfeasible to run due to increased costs.

Types of radiators

To understand why, we need to quickly look at types of water-based radiators. The main split is between ‘Conventional’ panel radiators and ‘Convection’ panel radiators. Let’s focus on normal room-heating radiators and forget for a moment about niche ones like towel rack radiators.

Conventional radiators are the large types you might think of when you think of a “Victorian radiator” – these tend to be a single large mass, usually made out of metal, that’s heated up with hot water from your boiler. This heat is then radiated out into the room.

A common type is a single-panel conventional radiator, these tend to be found in homes built from the 50s & 60s until the mid-90s – they’re usually single slim, flat panels. These tend to have lower heat output due to being smaller, but also have the benefit of being able to fit into tighter spaces.

Conventional-type radiators require a lot of energy to heat them up in the first place simply because it takes quite a lot of energy to heat up a large mass of metal – so they can operate adequately with a gas boiler but will significantly hamper efficiency with an air source heat pump.

Convection radiators, on the other hand, are likely to throttle efficiency far less. 

Convection radiators are those with a grill at the top – if you look down at them through this grill, you’ll be able to see thin metal fins snaking along the length of the radiator. Options commonly available for these are single, double, or triple panel models. Convection radiators are much better at outputting heat from the radiator pipework because they pack a lot of surface area into a small space.

This, essentially, means that there’s a lot more surface area from which the heat is able to radiate from.

Why would you need to upgrade radiators for a heat pump?

The key to getting air source heat pumps working as efficiently as possible is by making the heat of the water flowing through the heating pipework (what we call the “flow temperature”) as low as possible to comfortably heat your home. 

When a gas boiler is turned on, the gas will ignite and heat the water up to potentially 80°C or more before pumping that water around the radiator pipework for it to be radiated out. This high output might seem like a benefit, but is actually a requirement due to the lower output of the radiators. A lot of that heat gets locked up in heating up the thick metal of the radiators and doesn’t effectively get to the other parts of the room.

Another problem is that properties with modern radiators tend to experience frequent cycling as a result of really hot gas boilers and really high radiator output. That is, the boiler will turn on, output a lot of heat in a short amount of time, turn off again until that heat has dissipated, and repeat the cycle. This is something that many customers find quite unpleasant in the coldest months! They get blasted with heat, get cold again in half an hour, and the cycle repeats.

Because heat pumps work by tapping into a temperature difference from the outside air, they sometimes have a more limited maximum output temperature than a gas boiler, but this also means that they’re able to provide a consistent temperature over a longer period of time, so you avoid the problem of the heating cycling inefficiently.

If, for example, you’re able to run your air source heat pump’s flow temperature at 45°C instead, and the radiators are able to effectively release a lot of that heat rather than locking it up themselves, then your heat pump can run continuously with a much lower energy draw than it would otherwise need.

You’re able to opt for a high-output heat pump & upgrade radiators later

If the added cost of upgrading radiators isn’t something you can absorb at the moment, you also have the option of installing a high-temperature air source heat pump and running a higher flow temperature through your home’s pipework. You can then choose to upgrade to more efficient radiators in the future and turn the flow temperature down to a more efficient level in order to maximise energy & cost savings.

Though, as we elaborate on lower down, you can now also factor radiator upgrades into a financing plan.

Benefits of upgrading radiators as part of a heat pump installation

However, whenever we feel it’ll benefit to upgrade, we’ll always recommend that you upgrade your radiators at the point of installation for a few reasons.

1. Effective system planning

Firstly, this means that system designers are able to effectively plan system output & operational efficiency by pairing particularly suitable heat pumps and radiators for your home – so you’ll usually be left with a much more efficient system.

2. Effective project management

Secondly, while radiator replacements add to the overall time that an installer has to be present, installing them as part of the same project lets the engineer better plan that time to get the job done as quickly as possible.

Having to contract a separate engineer years into the future usually means that they’ll have to waste time becoming familiar with your home’s system, the heat pump installation, and the necessary type & heat output of the radiators. There’s also no guarantee that they’ll be qualified heat pump experts.

3. Lower operational cost

Getting the maximum efficiency possible out of your heat pump system, over the whole year, means that you could save significant amounts on your energy bills. Depending on a few factors, of course.

For example: if you’re replacing an old G-rated gas boiler and keep your energy tariff the same, you could be saving up to £340 a year on energy bills. For more information on what affects heat pump efficiency, read our dedicated efficiency page here. 

4. Cost can be factored into a financing plan

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. We’ve worked with our lending partner to agree on covering the cost of radiator upgrades, so you can have everything done for a single sum, and pay it off in a way that you can best manage.

Need advice on your heat pump upgrade?

We draw from over 20 years’ experience at the forefront of the heat pump industry and pride ourselves on a fully bespoke service, tailored to your particular usage requirements and home – so we’re always on hand to talk about problems you’re having or worries you have about investing in a heat pump system.

It’s a significant investment into your home and future, so it’s worth getting it right from the start by working with trusted experts. Get in touch today.

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