Can you install underfloor heating with a combination boiler? Here we explain the pros, cons and costs.
- Is It Possible to Have Underfloor Heating with a Combi Boiler?
- Pros and Cons of Underfloor Heating with a Combi Boiler
- Will I Need to Upgrade my Combi Boiler?
- Why Might I Need Larger Radiators?
- Cost of Underfloor Heating with a Combi Boiler
- Should I Opt for a Combi Boiler or Heat Pump with Underfloor Heating?
While a heat pump is the most common system used with underfloor heating, is it possible to stick with a combi boiler and if so, what are the costs?
In this guide, we’ll discuss whether you can have underfloor heating with a combi boiler and how this would compare with a heat pump-underfloor heating setup.
Let's explore...
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Is It Possible to Have Underfloor Heating with a Combi Boiler?
Yes, it is entirely possible to have underfloor heating added while sticking with a combi boiler.
However, you’ll either need to have your combi boiler adapted to ensure it can work sufficiently with underfloor heating, which typically involves the installation of a two-port valve.
In addition, you may need a new combi boiler installed with a higher power output - the size required depends on the size of the area you want to have your underfloor heating.
Your current boiler may be sufficient, but again, this will depend on the area you want to have underfloor heating operating.
Pros and Cons of Underfloor Heating with a Combi Boiler
So, what are the arguments for and against having underfloor heating added with a combi boiler?
In this guide, we’ll lay out the pros and cons to help give you a sense of whether it’s the right choice for you.
Pros:
Starting with the advantages, one of the key benefits of sticking with a combi boiler is that it will save you money in the short term.
After all, by opting to continue using your combi boiler (or even if you were to have a new one installed), you’ll avoid the hefty upfront cost of having a heat pump installed.
Along with avoiding the expenses associated with a heat pump installation, you could avoid the disruption caused by such an installation too.
Cons:
While there are some upsides to having a combi boiler installed with underfloor heating, there are many disadvantages.
Firstly, you will likely face higher energy bills with underfloor heating than would be the case if you were to opt for a heat pump.
Moreover, a heat pump is a more efficient option. In contrast, a heat pump solution is up to 40% more efficient than a boiler and radiator system.
Beyond that, additional work will still be needed to ensure that your combi boiler is suitable for underfloor heating.
As mentioned this includes the installation of a two-port valve, as well as having your combi boiler resized i.e. fitting a new boiler.
For instance, if you had underfloor heating installed in one room, while radiators were in the rest of the house your combi boiler would need to have a two-port valve installed.
A two-port valve controls the flow of water in a central heating system, in particular the water that goes from the boiler to other parts of the heating system.
If this isn't installed, your boiler might end up heating your radiators and underfloor heating simultaneously which may cause it to overheat, triggering a fault.
Will I Need to Upgrade my Combi Boiler?
If you do opt for a combi boiler-underfloor heating setup, you may need to have your existing boiler replaced with a larger model.
By larger, we are referring to the power output and not necessarily the physical size of the boiler.
It will also need a suitable flow rate. What’s more, modulation capacity is also relevant as a suitable modulation will enable improved efficiency.
Getting the ideal boiler can make sticking with a combi boiler a more sensible option, hence, there’s a good chance you’ll find yourself upgrading your boiler.
The best way to approach this is to consult with a qualified heating engineer to help determine what sort of combi boiler would be a good match for the underfloor heating system you wish to have installed.
Of course, they’d also need to factor in radiator use, if you’d prefer a hybrid approach (i.e., using underfloor heating and radiators).
One notable advantage of taking a hybrid approach is that by opting for radiators in one area of your home (e.g., upstairs), there’s a good chance that the overall cost of the setup will end up lower.
This is especially so you can avoid the need to have your radiators replaced with larger units (more on that in the next section).
Why Might I Need Larger Radiators?
For a hybrid approach, larger radiators may be required. If you wish to use underfloor heating and radiators, there are two ways to make it work.
On the one hand, you may need larger radiators so that they can run at a lower flow temperature. This is because larger radiators have a lower flow temperature.
Since underfloor heating runs at a relatively low flow temperature, matching the radiator’s temperature to that of the underfloor heating is one way to make a hybrid system work.
Alternatively, you could in theory run the radiators at a high temperature and underfloor heating at a lower temperature.
However, they would need to be separated with various valves to create distinct zones.
Also, a blending valve and buffer tank would typically be required to cool down water for your underfloor heating installation.
Obviously, if opting for this solution, you’d need to verify with the heating engineer that everything is considered for a suitable setup.
Cost of Underfloor Heating with a Combi Boiler
The price of having this system established will depend on a wide range of factors.
Firstly, the size and type of underfloor heating used will play a major role in shaping the price.
Beyond that, it will cost more to have an existing property renovated for an underfloor heating installation than to have one fitted to a new build property.
As for the use of a boiler, whether or not you’ll need to have it replaced will obviously shape the total cost too.
Then you’d need to take into account whether or not you wish to use radiators and whether your existing ones would need replacing.
As mentioned, a hybrid system should cost less overall.
Aside from the above points, the price of labour will vary depending on where you live, ease of access to the work area and the complexity of the installation work.
Lastly, the cost will also be shaped by the quality of the appliances used (e.g., a high-end combi boiler vs. a budget-friendly option).
Here are the average costs of different underfloor heating-combi boiler setups: *
Dry Underfloor Heating with House Renovation and New Combi Boiler - £3,800 to £8,800
Wet Underfloor Heating with House Renovation and New Combi Boiler - £7,800 to £17,300
Dry Underfloor Heating in a New Build Property and New Combi Boiler - £2,500 to £5,300
Wet Underfloor Heating in a New Build Property and New Combi Boiler - £4,800 to £10,800
*These prices cover the range of costs for different underfloor heating systems based on their size.
If you were to stick with an existing combi boiler, it would reduce the overall cost by approximately £800 to £2,800.
As for the use of radiators, again a hybrid approach is likely to prove less costly too.
Should I Opt for a Combi Boiler or Heat Pump with Underfloor Heating?
The best option for you will depend on a wide range of factors.
For example, if you are more concerned with long-term savings, a heat pump may very well prove a worthy investment.
However, if you want to reduce upfront costs, opt for a combi boiler.
On average, an air source heat pump usually costs between £12,000 and £17,000 to have installed.
On the other hand, it would likely cost around £15,000 to £25,000 to fit a ground source heat pump.
With that being said, if you are based in England or Wales you may be eligible for a £5,000 to £6,000 reduction in the total cost through the Boiler Upgrade Scheme (BUS).
There are pros and cons to each option. Therefore, you should carefully weigh up these points before choosing between a combi boiler and a heat pump.
If you’re stuck, you may want to consult with a qualified heating engineer for tailored advice.
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