11 November 2011
Frequently Asked Questions on Underfloor Heating
Expansion joints are a standard construction detail used with floor screeds in which the underfloor heating is normally embedded. Surprisingly, neither plastic pipes nor electric cables possess the strength or ability to crack a screed which has cured. Any failure will be directly attributable to the screed material and its use. Please check that expansion detailing has been considered by your screed provider.
Systems normally include an 8mm expanded polyethylene foam expansion joint around all perimeters of every room to allow for thermal expansion of screed. Additionally an expansion joint is included wherever a Main Building Construction Joint exists, plus across all room doorways, corridor Fire doors, and in awkward shaped rooms over 40 square metres area (longest side 8 metres) to avoid radial cracking, but this does not always apply to Liquid Anhydrite screeds.
It is necessary to apply an expansion joint at regular intervals along very long access corridors, and to note that changes of direction can cause additional stress relief joints at relatively short distances
This is a complex subject, but in simple terms underfloor heating is more efficient because:
- it uses lower temperature water (typically 35°C to 50°C rather than 70°C) so less energy is needed to heat the water
- it enables condensing boilers to condense more often
- the nature of the heat (radiant) provides a comparable comfort level at a lower air temperature
- the distribution losses are lower
- Water based systems are covered by BS EN 1264 Parts 1, 2, 3 (Design) and 4 (Installation).
- Electric Cable Systems are covered by BS 1018:1971 (Reviewed 1993) mainly for Night Storage systems whilst the newer Mattress and Prefabricated Element systems for under tile or similar systems are covered by EURO-Norm IEC 60364-4 and partly by the Electricity Council Design Guide
- Floor screeds and finishes are covered by BS 8204 (2005) Parts 1-7, BS 8203, and DIN Standard 18560 Parts 1-7 – the latter being a longstanding Europe wide reference standard
- Timber floors and timber finishes are covered predominantly by BS 8201 in the UK.
Yes. There are companies that supply UFH that do not belong to BEAMA, however members of BEAMA have to complete a lengthy membership process that helps to ensure that:
• The components supplied meet the relevant European and British standards, comply with testing regimes, and have been produced in a quality assured factory to help traceability
• That systems are designed and specified according to the latest updates to the core European standard EN 1264 and the current building regulations and compliance codes
• That systems and components have robust warranties / guarantees that are either insurance backed or are provided by large well-financed businesses.
BEAMA members can determine the best system for individual projects across a range of design parameters.
While membership of BEAMA does not guarantee a members work, people find it reassuring to know that BEAMA members have to have successfully trade in the sector for at least two years before they can join.
If a company isn’t a BEAMA member you have to ask yourself “why not?”
For a full list of members click here
There are a number of visual and manual fault finding actions:
- Check whether the heat source is working correctly (e.g. the boiler or heat pump)
- Check that the circulating pumps are functioning
- Identify whether the controls are calling for heat
- Is the mixing valve working properly?
- Is the room thermostat turned up to the required level?
- If you have a flow gauge check whether it indicates distribution flow
- Check if actuators are working (are they warm when heat is called for?) If not contact an electrician.
A wide range of systems are available and each BEAMA member promotes their own preferred systems. BEAMA members have systems suitable for floor, ceiling or wall fitting; for renovations, extensions or new builds; for domestic or commercial projects; for heating or for preventing overheating or for both; for background heating or primary heating; for mixing with other heat emitters; for all types of heat source; for solid, timber or floating floors.
The range is wide, and whilst BEAMA cannot suggest any particular system or application you can be sure our members will be able to give you good sound advice. As useful guidance, vinyl and stone floors provide best underfloor heating performance followed by laminates. Performance is lowered with carpet but of course this will depend on the thickness of the pile.
BEAMA sets the standards and model syllabus for UFH training, whether for installation, first fix, or design. It has a process for recognising courses.
Currently independent courses are offered by:
- BPEC either through independent training facilities, colleges or manufacturer sites
- Logic Certification
If you want to find out which manufacturers offer training then look at the member micro sites in our membership directory section. Just click on the company name and the micro site appears.
We recommend in all cases that you should contact your supplier but we are happy to clarify any technical queries where we can.
If you are looking for an installer or contractor, you can look at the member directory where some companies state that they provide a full underfloor heating service.
For a wider range of installers or contractors contact these organisations:
- Association of Plumbing and Heating Contractors
- The Institute of Domestic Heating & Engineers
- Chartered Institute of Plumbing and Heating Engineering
For advice on the use of timber based floors with underfloor heating, contact the manufacturer and these associations:
Floor temperature has to be viewed in proper context. Without a temperature difference between the floor and the room there can be no heat transfer, so it is the room heat requirement which to a great extent will affect the choice of floor finish and can occasionally completely change preferences.
However the current Building Regulations require such good thermal insulation in construction that only the Renovation projects (old buildings) have to re-consider the suitability of a floor finish.
- BS EN 1264 Part 2 sets the maximum foot comfort temperature as 29°C
- Part 4 sets floor limits for wet rooms (33°C) and perimeter zone up to 1m (35°C)
- Vinyl Flooring (standard products) carry a 27°C surface temperature limit
- Linoleum flooring is considered as similar to vinyl with a 27°C surface temperature limit
- High Duty Plastic sheet flooring may be available which accepts a 29°C maximum limit
- Carpets and Carpet tiles will accept any floor temperature in the range permitted
- Floor covering manufacturers will be able to provide specific information.