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Underfloor Heating – FAQs

UFH Specialists
Since 2004

UK Wide
Installation Team

All-in-one
UFH Service

Specialist UFH
Repairs Service

Which Underfloor Heating is Best, Electric or Water?

Both underfloor heating systems achieve the same thing, 21 degrees is 21 degrees whether you use electric or water. As a rule of thumb warm water underfloor heating systems are cheaper to run over the long term, electric underfloor heating can be cheaper to install but costs more over the longer term. We generally recommend water systems wherever possible due to their more economical nature.

How Much Does Underfloor Heating Cost to Run?

Water underfloor heating systems are typically 20 percent cheaper to run than a traditional radiator system powered by a Gas boiler. Electric underfloor heating systems are cheaper to run than Oil, LPG, and Electric storage heaters for those who are not on the gas network.

What Floor Coverings Can I Have on Top of Underfloor Heating?

You can almost any type of floor covering over underfloor heating, this includes but not limited to: Amtico, Karndean, Marmoleum, Laminate, Engineered Wood, Carpet, Tiles and Stone.

What’s the Maximum Thickness of Floor Covering?

Engineered woods no more than 22mm, Stone and Ceramic tiles have a good thermal transfer and we have installed underfloor heating under 50mm flags to good effect. Carpet and underlays need to have a combined tog value of 2.5T or less (yes, carpets have tog values!)

Do I Need Floor Insulation?

Yes we strongly recommend the use of insulation otherwise you could have a heating system that is very un-economical to run. More insulation is better in this situation where floor heights permit.

What is the Cost of Installing Underfloor Heating?

This one is hard to answer in general, the cost will depend on your project and the ease of installation. Most projects can be completed in one day and others take weeks such as large commercial installations. We look at each job on its own merits and listen to your needs, we can design a system that suits your property, we do not install systems that are not suitable for you or your property.

What’s the Minimum Screed Thickness for Underfloor Heating?

By selecting the correct screed we can go low as 40mm screed. This is the minimum before the screed becomes weak, and the plus side you will save money in material cost and the underfloor heating system will heat up quicker.

How Long Before I can use my Underfloor Heating after Screeding?

It all depends on the type of screed, but some systems can be turned on as soon as 2 days after installation, others can be 7 days longer.

What’s the Drying Time for Floor Screed with Under Floor Heating?

Again this is entirely dependent on the type of screed used.

Which Areas of the UK do you cover?

We cover all of the UK, but most of our work comes from Yorkshire and Lancashire, Midlands, North East and North West.

What Happens if my Water Underfloor Heating Develops a Leak?

Assuming the leak is obvious we can easily locate the damaged section of the pipe and repair it.

Should I Leave my Underfloor Heating on all-day?

We suggest leaving the system ticking over during the day and using the set-back feature on the thermostats overnight to keep the heat in the floor and to not allow the slab to go completely cold. For example, if your day time temperature is 21 degrees Celsius, we suggest allowing the system to cool down to 16 degrees, then in the morning the heating system hasn’t got to do a lot of work to come back up to 21 degrees.

what Brand of Underfloor Heating do you Install?

We mainly supply and install Emmeti underfloor heating systems, but we have also fitted Polyplumb AKA Polypipe and JG Speedfit – we have used Nu-heat underfloor heating, Robbens underfloor heating is another one we use, also products from Underfloorheating1 at Doncaster, rehau – We prefer to useEmmeti but we are happy or quote you using your preferred system – we don’t normally supply and install products from Wickes underfloor heating or b&q underfloor heating, but screwfix do a half decent range.

How Much Screed Is Required Over Underfloor Heating?

This depends on the type of screed – but if its a flowing screed then we can go as low as 40mm – the norm is 50mm and sand & cement screeds about 65-70mm.

How much to install underfloor heating?

This questions is hard to answer – its based on each individual project, and no two jobs are ever the same, what we will do is promise to be as competitive as possible and the only way to find out the cost is to contact us using the form on the right or phone 01274 568 536

How Many KW in 200m² of Underfloor Heating?

To find out simply multiply 70w x m²

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169 thoughts on “Underfloor Heating – FAQs

  1. Can you tell me how water hardness might affect underfloor heating?
    We are planning to move to a new property in an area with very hard water in Wiltshire.
    I am concerned that lime-scale precipitation will fur underfloor water pipes.
    Apart from installing a water-softener, can furring be minimised by keeping the water temperature within a certain range?

    1. Hi Mike, This is difficult to answer, if the heating system has been maintained correctly with “inhibitors” then it’s likely to be ok and in good condition. It is situations where no inhibitors have been put into the system from new or repair work in the past.

      My advise would be to have the manifold inspected prior to exchange of contracts, this way then you will know what condition it is in.

      Products like https://www.sentinelprotects.com/uk/products/sentinel-x100-inhibitor and https://www.sentinelprotects.com/uk/products/x700-sanitiser-and-biocide are designed to fight against limescale.

  2. Our electric underfloor heating was installed by professionals under ceramic tiles. My question is; can the wiring be damaged by boisterous jumping by my grandchildren?!

  3. Hi, I need to move my manifold by extending the ufh pipes. 1. Is this possible? 2. If so what is the best fitting to extend the pipes – ie compression etc.

    Thank you

    1. Hello – yes this is possible, we wouldn’t recommend “compression fittings” normally, its better to use specialist connectors such as “uponor quick and easy” joints – or Rehau “everloc” products https://www.rehau.com/download/790502/everloc-parts-list.pdf , both of these require special tools sadly.

      Assuming the compression joists will be accessible then they will be ok to use, they sometimes have a habit of leaking, but as i say if you can access them, then it wont be an issue.

  4. an a manifold in a central downstairs location feed up a floor, ie run 2 zones downstairs and 3 up a floor, really no location for a second manifold upstairs, do you need to do anything special to make this work

    see your answer to a prevois question which makes me think this can be possible

    Hi – Yes no problem, we often install manifolds on lower ground floors andie run feed another floor from the same location.

    1. Hi – yes that’s fine, and no you don’t need anything special to make it work, its no different to running rads upstairs from a boiler on the ground floor.

      Thanks

  5. Hi
    We’ve recently moved into a house with wet underfloor heating throughout and everything works fine except in the kitchen. It never gets warm.

    We have the heating on all day but each room has a programmable thermostat. The kitchen has been set to 25 but has never gone past 17 though it calls for heat on the manifold hence boiler is always on because of the kitchen.

    We’ve just had the thermostat changed in case it was faulty and it’s the same. I’ve had “UFH specialists” found via the manufacturer’s website round but they don’t seem to know. I’ve mentioned that based on what I’ve read online it could be air in the system or an electrical fault but they haven’t done anything except touch bits on the manifold and say all should be working fine plus leave with a call out charge.

    Any idea what the issue might be please and do you cover London area? Thanks

    1. Hello

      It could be one of the following or something else:
      Faulty Actuator
      Stuck pin valve
      Air lock
      faulty wiring
      crossed actuators

      Plus other things.

      Yes we do cover London.

  6. Our 12 year old conservatory is presently 29 degrees Celsius but the manual thermostat is still not switching itself off. We have electric underfloor heating. Why is this happening

    1. Its most likley because the relay in the rear of the thermostat has stuck on, despite the controller saying its not heating up. Its done well to keep going for 12 years!

    1. Hello, the industry norm is 2.5T of less combined underlay and carpet. The lower the tog the better it is.

  7. Hi there – I am putting wet underfloor heating in to a new space at home and the screed layer it sits in is 60mm deep and I have ordered 22mm thick limestone tiles. My builder was (apparently) expecting 12mm or so tiles and I asked if the extra tile thickness was an issue for underfloor heating. Your FAQ suggests not but thought I would ask you direct.
    Thanks.

  8. My under floor heating in the kitchen gets warm at times but the room stat is turned off & the heating programmer is also switch off.This is in a new apartment & is a wet system.What could the problem be.

    1. Hello – it could be a number of things, without been onsite or knowing more information i cant advise.

      Just one little tip – check the actuators are tight on.

  9. Hi we are going away for four months Nov/Feb because these are the coldest months in the UK my question is should we leave our underfloor heating on over this period whilst we are away ? Also is it safe to do so ?

    1. Hi we are going away for four months Nov/Feb because these are the coldest months in the UK my question is should we leave our underfloor heating on over this period whilst we are away ? Also is it safe to do so ?

  10. I have bought a flat with gas underfloor heating. I am changing the floors though as the ones in the flat are cheap looking and not nice. Do I have to change the whole system as well or is it safe to change the flooring only?

    1. Hello, it should be safe to change the flooring only – but you will need to give the flooring special consideration and the heating system set up: for example if your swapping from a wooden flooirng in the lounge to carpet, you need to make sure the carpet and underlay combinded are 2.5tog or less to be effective.

      Or if your swapping from carpet to wooden floors then make sure the underfloor heating cannot overheat the wood, and be careful putting rugs on top.

      Theres a few things to consider.

  11. Can i combine two seperate brands?
    For example, can I combine a Klima underfloor heating matt, with a Blyss sensor and thermostat?

    1. Hi – firstly i would check with the suppliers – but in my exeperience i dont see why not as long as the thermostat is rated to suit the heating mat.

  12. Hi,
    We are wondering about mixing wet and electrical underfloor heating. Putting wet underfloor in bedrooms, reception rooms and hall and electrical in the bathroom and kitchen due to its quicker turn on time. Do people mix both types of underfloor heating if installing at the same time?
    Thanks

    1. Hi, yes people do, our exeperience is wet UFH to full ground floor and electrical UFH to upper floor bathrooms for example.

      But if your install a full house of wet UFH it makes sense to use the same all the way through.

      Most systems these days are reponsive and lag times have greatly reduced when used with liquid screed or over-lay type systems.

      Hope this helps.

  13. Hi should I turn our underfloor heating off completely in summer or leave thermostats left on low as in the winter?

    1. Hello – leave the thermostats on low as in winter. In my experience thermostats dont like having the power cut to them for the summer – its best to leave them “live” if you will on a low setting.

      Russel.

    1. Hi – Yes it can, its not different to fixing any other pipe in the home, this can be done with compression connectors or other items like Rehau “evalock” and Uponor Q&E (Quick and Easy)

  14. Hi
    We have just had underfloor heating fitted and put the heating on for the first time. Stat put on at 21 degrees and been on all day and only gone up to 17 and floor does not feel warm underfoot? Is this normal, I was under the impression it would feel warm underfoot.

  15. We had just had a liquid screed poured over our wet system underfloor heating pipes. It was supposed to be 50mm screed covering 30mm over top of pipes but now discovered the screed is only 35 – 45mm thick, the average being 40mm. Not sure what to do ???

    1. without knowing the exact product etc, avg of 40mm is normally fine for liquid screed.

      what did the installer say when you raises your concern?

    1. Sure you can – just be careful when choosing what flooring your having, for example carpet and underlay need a combined tog value of 2.5tog or less for underfloor heating.

  16. What size boiler is required for an underfloor heating installation of 200m2. The property is built in 2009 and is well insulated. All windows are double glazed.
    The ground floor if concrete and the upper floor suspended with pipes on plywood and sand screed. The floor covering is carpet.
    Thanks CH

    1. Hello – sorry we cant help on this one, you need to ask the heating engineer who is doing the job for you to carry out their own calculations.

  17. Designing a self build – our architect has designed a heating room in integral garage for manifold & pipe work etc – presumably we should insulate this and pipes to maximise efficiency of system? Any suggestions?

  18. Turning on underfloor heating for first time screed has had 6 months to dry
    What temperature should I start at and when am I able to turn it up day by day or week by week

  19. Manifold positioned centrally in House. Can I have the boiler located in integral garage which is approx. 10m away?

    Also can the boiler deliver to both a downstairs UFH system and an upstairs conventional radiator system?

    Finally can the boiler be a combo boiler?

    Thanks for any help you can give.

    1. Hi – Yes no problem, make sure the flow and return supply pipework is sized correctly.

      Yes by using 2 port motorised valves to “zone” the system – ask the heating engineer to plumb the system as “s-plan plus”

      Yes it can a combi.

  20. What thickness do I need to allow for for electric underfloor heating insulation + mat+ scream+ tiles ??? On top of timber floor

    1. Hello – using a 10mm tile backer board, screwed to timber sub-floor and latex compound on top we would allow approx 16mm – then if you use a 10mm tile and 5mm adhesive your overall build up would be 31mm give or take a few mm’s

  21. Hello, I am wondering what the best practice is for the on-going maintenance of underfloor heating in a commercial residential environment (large care home) – is it advisable to service the manifolds annually?

    1. Hi Robin,

      Happy new year.

      Yes defiantly – we suggest an initial inspection – put right any faults – then take out an ongoing maintenance contract for an annual inspection.

      Every year underfloor heating will throw different little issues and its worth keeping on top of these to prevent the problem getting worse.

      Below is a list we would check during an inspection.

      • Check manifolds for valve operation
      • Check the Actuators for correct operation
      • Check the circulating pumps for operation
      • Check flow rates (this is hard without more information)
      • Check Flow Temps via Thermal Imaging
      • Check the Mixer Valves for correct operation
      • Flush/Bleed underfloor heating pipework if required.
      • Test all the electrical system and confirm the thermostats are working
      • Fault find any electrical items that may not be working and correct.
      • Check the operation of any motorised valves
      • Check the boiler is engaging as and when it should be required
      • Fix and replace any items I can there and then (if I have the parts on the van)
      • Check anything else I can see that may need attention
      • Carry out Thermal Imaging Report to confirm pipe operation
      • This is not all the things we can do – but pretty much covers it.

  22. my husband is in intensive care in hospital and my son is trying to work out how to turn the uderfloor heating on. we only have underfloor heating in the conservatory and only have it on at christms and new year.Could you help me please?

  23. I already have underfloor heating fitted in some rooms of the house and I am looking at possible getting it throughout the whole house now.

    Can you advise if I was to tak up the exisitng tiles will this damage the underfloor heating that is currently laid?

    thanks

    1. Hello – Its a little vague to be able to answer this right now: Can you tell me what type of underfloor heating it is? electric? or water?

  24. Once a manifold has been installed, can this be moved? Also, can the underfloor heating pipes travel down and then up like normal copper pipes? As in, could they come out the manifold, drop 6 inches, then travel up to the level the heating would be?