Underfloor Heating
Common on the continent for some years, and pioneered by the Romans, underfloor heating is becoming popular in the UK.
Modern systems use a manifold in conjunction with a dedicated pump, linked to continuous circuits of plastic pipe under the floor.
Hot Water & Central Heating are committed to the benefits of underfloor heating – we’ve even installed it in our HQ in Edenbridge, so look no further if you need an experienced central heating installer in Edenbridge, Oxted and Tonbridge. We even cover the surrounding areas. Further examples are on our installation blog page.
Hot Water & Central Heating supply and fit;
- Velta Underfloor Heating Systems.
- Lagerstedt & Krantz Underfloor Heating Systems
Things you should bear in mind when considering underfloor heating:
Cost:
Underfloor Heating is far more expensive than radiators to install, in almost all circumstances.
If you are having a new subfloor constructed, or it is a new building, underfloor heating is relatively easy to incorporate at the construction stage.
If it is to be retro-fitted in an existing property, the additional building works with screeded underfloor heating in terms of screed thickness and insulation will be significant. Work by other trades stops whilst the pipework is being laid, and can only recommence when the screed is safe to walk on.
Benefits:
Underfloor Heating in concrete slabs provides a much more comfortable living/working space. The feeling of warmth from low down, and the reflected energy from the floor, makes us satisfied with lower room air temperatures than we would accept with radiator heating.
If you were to take two identical rooms, as a guide the room thermostat would need to be turned down by at least 1ºC in the underfloor heated room compared to the conventionally heated version.
This lowering of temperature without any noticeable deterioration of comfort results in a typical energy saving of 10%.
If you have a modern high efficiency boiler the lower operating temperatures of underfloor heating make further reductions in energy consumption due to the boiler working in ‘condensing mode’ for longer periods than with radiators.
Finally, if you are thinking about a heat pump instead of a fossil fuel boiler, the lower temperature water used by underfloor heating gives the best Coefficient of Performance from the pump.
Disadvantages:
Cost of installation, particularly if the building works are just for the heating provision and not part of other renovations you were doing anyway.
Having warmed a few tons of concrete up, it takes a while to cool it down again. So an unexpectedly warm or sunny day will make the property very hot indeed while the thermal mass of the floor cools down. Similarly, a sudden cold snap will result in a delayed reaction from the floor.
Some types of floor covering, for instance natural wood, can suffer by fast drying and shrinkage can occur. If the floor is properly acclimatised prior to laying this should not be a problem.
Is your house suitable?
The most important thing is insulation.
Heat from a floor can go down as well as up; houses built in the 1980s and before usually have no insulation under their concrete slabs. Underfloor heating will not work economically when laid on an uninsulated floor.
The costs of either excavating to insert insulation, or raising the the finished floor level to insert it, are significant.
Electric UFH versus water based UFH:
Electric UFH is vastly cheaper to buy and install. It resembles a knitted electric blanket and uses a network of mains 230v heating element wires.
At the time of updating this section of our site (December 2008) Natural Gas fired heating costs around 3.8p per Kwh, Electricity costs around 11.5p per Kwh. So any significant area of electrically heating floor will cost in the region of 300% more to heat, every day, for the foreseeable future.
The electric UFH is often recommended and fitted by bathroom fitters, conservatory and kitchen companies because it is cheap and easy; very often there is no insulation underneath. The running costs will be very high.
With electric UFH just a break in the small wires in the mat will cause a total failure.
In contrast, water based UFH consists of a number of endless loops of plastic barrier pipe, which will last almost indefinitely.
Finally, the heat output from water UFH is higher than electric systems.
So, to summarize, the only advantage of the electric mat systems is speed and cost of the actual installation. After that, it is uphill all the way.
Delay:
With the screeded type, five weeks should elapse after the screed is finished before you can put significant heat through the system. The pipe must remain pressurised during the screed curing cycle.
Contractors:
You should choose a company with experience.
‘Your builder’ is therefore not usually the best choice. Builders and heating systems are generally incompatible; even if they have no idea about underfloor heating most ‘will have a go’. Underfloor heating installation faults are usually buried in concrete or under expensive wooden floors, and will be very expensive to rectify.
Choice of boiler:
Most underfloor heating systems should not have water circulated in excess of 50 degrees centigrade. This is to prevent the screed cracking, and also to make it comfortable to walk on.
This is usually achieved by a water mixing pump attached to the manifold mixing in lower temperature water from the return circuit. Some boilers (such as Vaillant units) can be programmed to restrict their output temperature, which provides an extra level of protection. Because of the low water temperature requirements when compared to radiators, condensing boilers are a particularly good partner for a screeded underfloor installation.
So with a new high efficiency boiler, there is no better partner than underfloor heating.
