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If you're aiming for a cosy home with low running costs and you're already taking on building works, water underfloor heating could be for you. thermal actuator 24v
Although it can be expensive and difficult to install, it's typically inexpensive to run once it's in place, and an effective (and powerful) way to heat your home.
It's recommended for homes with hydronic heat pump systems , so if you're considering a heat pump either now or in the future, installing a wet underfloor heating system is a good way to prepare.
Here's a rundown of how water underfloor heating systems work and what's involved in the installation process.
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In a water-based underfloor heating system, a series of pipes circulates warm water under the floor to heat the space. These are typically connected to your boiler.
However, as a more sustainable option, you can also connect them to a solar water heating system or an air-source or ground-source heat pump.
You need something called a manifold to connect the underfloor water pipes to your heat source.
An underfloor heating manifold consists of two rows of taps, which allow the heated water to circulate from the boiler (or other heating source) through the underfloor circuits.
The system will also be fitted to a thermostat (or thermostats, if you have underfloor heating in more than one room or area) so that you can regulate the temperature of your floor.
Because it covers a larger area, water underfloor heating typically runs at a lower water temperature than radiators (the flow temperature can be as low as 35°C, compared with 55-65°C or even higher for radiators). This makes it an efficient, cost-effective heating option as compared to radiators.
The exact water temperature needed for underfloor heating will be determined in part by the flooring used to cover it. The harder it is for heat to get through the floor, the warmer the water running underneath it will need to be.
Most water underfloor heating systems will be installed with a mixing valve, which can adjust the water temperature to the desired setting. This also means you can keep the boiler running at the temperature you want for radiators in the rest of the house.
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Water underfloor heating is generally more expensive to install than electric underfloor heating because it is more complex. However, as it runs off the boiler (generally using gas), it is typically quite cost-effective to use.
Based on estimates from underfloor heating manufacturers around how much hot water you'd need, we've calculated that the annual running costs for water underfloor heating for a 10m2 room can be as low as £45 over a year.
This is significantly cheaper than electric underfloor heating, which in an equivalent sized room can cost as much as 36p per hour - or £33 a month if you used it for three hours a day.
Water underfloor heating is also typically around 25% more efficient than radiators. That's because the heat emitted from an underfloor system is more evenly distributed than heat from a single radiator, so the system can use water at a lower temperature.
Actual running costs for underfloor heating systems will vary considerably, as they are impacted by factors such as:
Check our guide to underfloor heating costs and installation to find out the typical prices for different scenarios based on information from the Royal Institute of Chartered Surveyors (RICS).
While it is sometimes possible for confident DIYers to lay electric underfloor heating themselves, water underfloor heating is best installed by a professional. This is because it's a more complex process, with plumbing connections and tests that need to be carried out.
If your home is suitable for water underfloor heating, the professional will first plan out the design and layout for the system. The pipes can then be laid and fixed.
Next, the pipes will need to be connected to a manifold, the heating system and a thermostat to control the heat for that room. Even if you've laid the pipes yourself, this part should always be done by a qualified plumber or electrician who can test the system.
Once the pipes are down and the system set up, insulating screed is usually put on top to hold the pipes in place, insulate the system further and to level out the floor. Some underfloor heating installers don't do this part – you may need to get it done separately by a builder.
If your installer can't complete the entire process, you can find a builder using Which? Trusted Traders . Ideally, get the installer and builder to co-ordinate their work so you're not left with an unfinished floor for too long.
In principle, water underfloor heating can be installed in pretty much any room, as long as you have the appropriate water pipework infrastructure in place and a suitable heat source (a boiler or heat pump, for example).
Because water underfloor heating is so powerful, and it runs off gas (which is cheaper than electricity), it is a good option if you want to heat multiple rooms.
in May 2024, we asked 41 Which? members with water underfloor heating to tell us more about their systems, including where they had it installed. Although some of our readers had it installed in one room (32%), the majority had it installed in four or more rooms (54%).
Bear in mind that water underfloor heating pipes take up more space than electric underfloor heating, and the floor must also be properly prepared and insulated to make the system work efficiently. This might mean having to raise the finished floor level.
There are low-profile floor systems available that you can have installed in an existing room without raising the floor considerably or significantly disturbing existing fittings, but you will need to consult with a professional to see if these systems will work for you.
The thickness of your heating will depend on the system that you choose, as they require different layers of material to run safely and effectively.
Water systems are generally bulkier than electric systems and can be around 130mm thick , or thicker if they are being retrofitted onto an existing floor.
Check our guide to underfloor heating costs and installation for more information
It can be difficult to know whether the benefits of water underfloor heating are worth the investment until you've already made the decision.
So, in May 2024, we asked 41 Which? members who've had water underfloor heating installed whether they thought it had been a worthwhile investment.
If you're a Which? member, you can log in to unlock our insights from members who already own underfloor heating.
Not yet a member? Join Which? today to see our advice, as well as exclusive underfloor heating cost data from the Royal Institution of Chartered Surveyors in our guide to underfloor heating costs and installation .
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Water underfloor heating typically takes 2 to 4 hours to warm up.
It is generally recommended that you run your heating on a schedule so that your house is never uncomfortably cold while you wait for it to warm up.
However, the system retains heat for a long time, as the warm water remains in the pipes.
Yes, water underfloor heating can be retrofitted.
This means the system can be fitted within the subfloor, without taking up floorboards or digging up the floor of your home.
However, only certain low-profile systems can be fitted in this way; the majority of systems are better fitted when you are already renovating your floor.
No. Underfloor heating works perfectly well with the types of boilers that most people already have in their homes, including combi gas boilers, traditional tank-based gas boilers and oil boilers.
However, your existing boiler may need some adjustments to work effectively with the underfloor heating system and, in a few cases, may not be suitable.
You should always get a professional to assess your heating system's suitability before committing to getting water underfloor heating installed.
Read more about underfloor heating systems or head to our guide to the best heating for your home
This article uses insights from the Which? Connect panel, collected from research activities with our members. Find out how to get involved
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