Yes! Heat pumps certainly work with radiators.
Heat pumps are sometimes installed along with underfloor heating in newer buildings, but that isn’t the case usually.
Conventional radiators require water to be heated to around 60°C to 70°C whereas underfloor heating only needs the water to be heated up to around 35°C. As a result, underfloor heating is more energy efficient as conventional radiators need a higher supply temperature to achieve the same room temperature. As heat pumps working with existing radiators (standard radiators), need to produce a higher supply temperature, their COP drops. As a result, their consumption of electrical energy is about 25% higher than with underfloor heating – to produce the same heat. Of course, they are still extremely efficient compared to other heating technologies. Whether you are best off with underfloor heating or radiators depends on many factors which we’ll discuss in a bit.
Do ground source heat pumps work with radiators?
Both ground source and air source heat pumps operate with radiators.
Can I use my existing radiators with a heat pump?
In most cases, yes, but it depends on the radiators already in place. You can use your heat pump with either radiators or underfloor heating, and it will work in the same way. Heat pumps will work with existing radiators almost certainly if they have been installed sometime in the last twenty years or so. But there are exceptions, so let’s take a look at them.
Would very old, small or cast iron radiators work with a heat pump?
Not all radiators work with heat pumps. Small and cast iron radiators are a challenge for heat pumps. That is because they need larger amounts of very hot water to heat the space. When radiators are very small or are made of cast iron, they require a larger heating capacity to function properly.
If you want to improve the heat transfer in your home, you might not have to install a high-temperature two-stage heat pump. Instead, you could replace your radiators with more efficient ones. If they are small radiators on a single pipe system and struggle to heat a larger space, then the system designed by the heat pump engineers will take it into account.
You may need to upgrade your radiators (to low temp, large radiators) in some cases or switch over to fan coils instead. These options will keep your home warm if your current radiators won’t, and at the same time you’ll avoid the hassle of installing an underfloor heating system.
To be absolutely sure your older or oversized radiators can work with a new heat pump system, get them inspected by your heat pump installer.
How do heat pumps work with radiators?
Air to water heat pumps (air-source) and ground-source heat pumps can work with radiators, underfloor heating or fan coils. Air source heat pumps work by capturing heat from the outside air. Ground-source units do the same but use the ground as a heat source. This heat is typically captured from the source and transferred by some form of a refrigerant.
As the refrigerant passes through a heat exchanger it transfers the heat to water. This is the water that circulates in your underfloor heating, radiators or fan coils.
Whether radiators are the best solution or not will depend on your needs and the building’s characteristics.
How well do heat pumps work with radiators though?
Heat pumps work well with radiators. The difference in efficiency between conventional radiators and underfloor heating is around 25%, with underfloor heating being more efficient. This may sound like an opportunity for great savings, but it isn’t that great considering the high investment cost of underfloor heating. To achieve the same energy efficiency as underfloor heating, you can use low-temperature radiators, or fan coils – which also offer cooling. We’ll compare radiator options in a bit.
Is it worth upgrading from radiators to underfloor heating?
Should you replace your radiators for underfloor heating? Not necessarily. The installation of underfloor heating in an existing building is no easy task and isn’t cheap. Investing in a domestic hot water heat pump and / or better insulation will offer greater efficiency and returns in the long run.
Can I install a heat pump with new radiators in a new building construction?
Certainly. Although the adoption of underfloor heating is growing, a good option to consider is the use of low-temperature radiators. These operate with a lower flow temperature, allowing the heat pump to work at a higher efficiency, whilst providing almost the same benefits as underfloor heating.
Is underfloor heating preferred to radiators?
Not necessarily. Each option has its pros and cons. Your current situation will also play a role in this decision. For example, if you are already using radiators it is highly unlikely that it’s worth upgrading to underfloor heating. If you are constructing a new building, you may consider underfloor heating, but it still isn’t as common as radiators. You should also consider fan coils as an option if you want to use the system for cooling as well. Each solution has its advantages and disadvantages. Let’s take a closer look.
What are the pros and cons of using underfloor heating with a heat pump?
The advantages of using underfloor heating with a heat pump are:
- Underfloor heating can be up to 25% more efficient than conventional radiators (when used with a heat pump) as it doesn’t need water to be heated to a high temperature.
- You can select which rooms to heat individually with proper zoning.
- Underfloor heating doesn’t take up any precious wall space and looks more modern.
- The warmth that underfloor heating gives is equally spread across the house.
The disadvantages of using underfloor heating with a heat pump are:
- The installation cost is high and may not be recouped by the efficiency gains.
- Heat distribution is slower, and it takes longer to heat up a space.
- Replacement can be very disruptive.
What are the pros and cons of using radiators with a heat pump?
Radiators, or rads, are a time-tested solution for heating your home. They have many advantages, making them a worthy consideration for your new heat pump installation.
- Radiators are relatively economical and will cost less than an underfloor heating installation.
- You can select which rooms to heat individually with proper zoning.
- Radiators designed for low temperatures are equally efficient as underfloor heating and don’t cost as much.
- They are easy to replace in most cases without disrupting the underfloor hydraulic piping.
- They are very responsive and quick to warm up a space.
However, there are some disadvantages to radiators too:
- Conventional radiators (not low temp radiators) can use 25% more energy than underfloor heating.
- Larger radiators take up valuable wall space.
- Conventional radiators are prone to corrosion over time.
What are the pros and cons of using fan coils with a heat pump?
Fan coils also work with an air or ground source heat pump and have many advantages:
- Fan coils don’t make heat pumps work harder as they can operate at low flow temperatures just like low temp radiators. This means greater energy efficiency gains – so more savings.
- Fan coils can also provide cooling.
- They are quick to cool down or heat your rooms.
- They can also provide greater indoor air quality through filtration.
- They can be set up using zoning for different spaces in your home.
- They are flexible to install and don’t require extensive work done under your floors.
Fan coils also have some disadvantages:
- They can create drafts while moving cool or warm air indoors.
- They are not absolutely silent as they use fans.
- They require regular maintenance and filter changes.
- Aesthetics may be a consideration as they may be a little harder to integrate seamlessly into a space.
What are the best radiators for heat pumps?
New radiators are better than existing radiators – if they have clocked many years in operation. Their performance degrades slightly over time due to corrosion.
Newer models are significantly better than older models. Improvements in their design such as a larger surface area provide an increased heat output.
Low temperature radiators are the ideal radiator type to use with a heat pump. These radiators don’t require a flow temperature as typical radiators (60°C to 70°C) and can heat a room while using a flow temperature of just 45°C or less. This is very similar to underfloor heating and emits enough heat to get a good result while at the same time reducing energy consumption between 20% and 30%. The level of heat you get with these hot water radiators will vary based on the insulation of your home. These are the best radiators for a heat pump system.
Aluminum radiators offer faster heating times. These powerful radiators can give off more heat while also taking up less space. Combining steel and aluminum radiators would result in corrosion problems, so your heating system should only use one type.
Fan assisted radiators (convector radiators). These could be any type of radiator that is fitted with a fan. Their output temperature is the same as the conventional radiators, but they use a fan to circulate heat. They may be more energy efficient in some cases where you want to circulate the heat more.
Use the services of a heat pump installer to check heat pumps and radiators to ensure they are compatible to heat your home.
If I want to keep my radiators, does it matter if I install a ground-source heat pump or an air-source heat pump?
Air source heat pumps use the heat of the air outside and transfer it to the radiators in your home. Ground source heat pumps use the ground’s heat to warm your home while the radiators help distribute it in the rooms. Since the ground offers a more stable heat energy source in colder climates, it is more efficient. Generally speaking, using an air source heat pump system with radiators works just as a ground source system would. However, the efficiencies differ. Before investing in a ground source heat pump installation, it is important to consider whether the long-term cost savings are worth the higher initial investment.
Would a combination of radiators and underfloor heating work?
Yes, certainly. This is called a hybrid or mixed heating system. Existing radiators will work with such a system in many cases. Combining both distribution systems offers few advantages though, and comes with many drawbacks. You can use the faster heating of radiators to warm up spaces quickly and selectively. You can also use the underfloor system to provide radiant warmth across your entire home.
There are many disadvantages to combining these two systems. Most importantly, to achieve the heat you need the heat pump will have to work harder as the radiators require a higher flow temperature. As a result your system won’t work as efficiently. This also brings more complications that require more planning for zoning and the connections. In addition, you will have greater maintenance needs for two systems. Your heat pump system will need to support such a mixed heating design.
This is why it’s best to avoid such a hybrid system if possible. Connecting the heat pump to a single system – whether that is low-temp rads, underfloor heating or fan coils is the best way to maintain a high efficiency and reduce installation complexity.
Can I keep my old radiators when installing underfloor heating?
Possibly, but it isn’t advisable. There may be compatibility issues due to the different operating flow temperatures and other technical aspects. For the sake of efficiency, it’s better for heat pumps to operate at a lower temperature using only the underfloor heating. It is advisable that the old radiators are removed. Not only will you have more wall space freed up, you will not have to maintain an aging system which will eventually need to be removed anyway.
What are the requirements for installing a heat pump with radiators?
If you are using conventional radiators, you will need to choose a heat pump that will have a sufficient high flow temperature. Most low flow temp models are not advised unless you have big radiators that use water at a low temperature.
You can test your existing radiators using the following experiment. During a cold winter, lower your boiler’s flow temperature to 55°C to see if the heating provided feels adequate. If it is, then you can choose a heat pump with a 55°C supply at the design temp (for that minimum outdoor temp).
When your heating specialist evaluates your home, they’ll consider multiple factors to find the most effective solution for your heating requirements. Some of these include the type of insulation you have, radiator sizing, the flow temperature requirement, the heat pump capacity, your home’s hydraulic design and zoning needs as well as your heating preferences.
These factors will affect the system design as a whole. If you would like some help, speak to one of our heat pump installation engineers.
