Underfloor Heating - Frequently Asked Questions
Use the following list of questions you may have to find out more about the basics of underfloor heating:
- What are the Features and Benefits?
- How does it work?
- Where can Underfloor Heating be used?
- Why is Underfloor Heating not more widely used?
- What is the effect of floor coverings?
- Can Underfloor Heating be used with radiators?
- How do you control Underfloor Heating?
- Why is modern Underfloor Heating more efficient than radiators?
Need to know more? Try these links...
If you've mastered the basics, find out more about the product options available to you.
- Screed Pocketed Polystyrene
- Timber-Floating Foiled Polystyrene
- Timber-Joists, Battens, Floating Pipe-In-Panel Modules
- Timber-Joists, Battens, Foiled Polystyrene Panels
- Timber-Joists Pipe-In-Polystyrene Modules
- Timber or Screed - The Ultimate, Jigsaw Approach
What are the Features and Benefits? [top]
Warmfloor's selection of underfloor heating offers the following features & benefits:
- it is the most comfortable form of heating of all
- it is more energy-efficient than radiators
- it is completely unobtrusive
- it is completely safe - there is nothing to burn you or bump into
- it is healthier - there is less dust in the air
- there are no heaters to clean or repair
- there are far fewer dust mites
- it is very durable - the pipe will last longer than 50 years, much longer than radiators
- it needs no specialist knowledge or equipment
How does it work? [top]
Heat in general is transferred from a warm area
to a colder area in any of three ways:
• conduction
• convection •
natural radiation
Of these, our bodies find natural radiation to
be the most comfortable because this is how the
sun heats us.
Radiators transfer
heat energy by convection from a small surface
which must be very hot by comparison with
the room itself. Typically, a radiator must
be 70-80oc which is hot enough to burn you.
Air which is in contact with the radiator
is heated.
As it warms, it rises towards the ceiling
and is then pushed across the ceiling by
more warm air coming behind. As it crosses
the ceiling, it cools and starts to drop.
As it drops, it gives up its energy to the
room, its furnishings and its occupants.
When it is at its coolest, it returns across
the floor to be reheated, and the cycle
is repeated.
Underfloor
heating transfers heat energy by natural
radiation from a very large surface which
only has to be slightly warmer than the
room itself. Radiant energy is emitted
from the floor in every direction. Some
strikes the walls, the furnishings and
the ceiling where it is partly absorbed
and partly reflected.
As these surfaces absorb energy, they
warm up as well and become secondary emitters,
until heat energy has been reflected or
absorbed by every part of the room. There
are no hot ceilings and no cold floor
draughts, just even, all-round comfortable
warmth
Where can Underfloor Heating
be used? [top]
In almost any building and with almost any form
of floor construction, whether in a new-build
or refurbishment.
Why is Underfloor Heating
not more widely used? [top]
It is! In various European countries it is very
widely used. In France, it accounts for 40-50%
of all heating. In Germany for 50-60%. In Switzerland
and Sweden, for even more than this.
In the UK, it currently represents 2% of heating
but this is increasing quickly.
Underfloor Heating
costs slightly more initially than radiators
but UK customers, like their counterparts
in Europe, are willing to pay the small
premium for much greater comfort and lower
running costs which underfloor heating brings,
and expect their builders to give them the
choice.
We used to think that buying double-glazing
was an extra cost on a building whereas
now, it is seen as a disadvantage if it
is not fitted. Increasingly, users realise
that an investment in underfloor heating
will be repaid many times over when they
come to sell their property.
In the UK, underfloor heating is the fastest growing
part of the heating market
What is the effect of
floor coverings? [top]
ThermoBoard products can be used with a variety
of finishes.
• tiles
• timber • carpet • vinyl
Advice should be sought about using any floor
finish with a resistance greater than 1.5 Tog.
Can Underfloor Heating be used with radiators?[top]
Yes, it can be used in conjunction with towel warmers or radiators.
How do you control Underfloor
Heating? [top]
Radiators are generally
controlled by thermostatic valves which
are set to a single level. If you want a
room cooler during the night, it is usual
to turn the heating off altogether, otherwise
you would be too warm.
An underfloor heating system has more sophisticated
controls. A room thermostat is used to operate
a motorised valve to turn off the flow of
hot water through the pipe when the room
is warm. Using modern programmable room
thermostats, the room temperature can be
set to different demand levels at various
times during the day (or week).
Why is modern underfloor heating more efficient than radiators? [top]
There are 5 reasons:
- Radiators are invariably placed beneath a window because
of the way convection works. If they were
sited on the wall opposite a window, the
cooling air dropping from the ceiling would
be cooled more quickly as it met the cold
window glass. This would create an uncomfortable
downdraught from the window and pull cold
air onto the floor. Sitting them beneath
the window minimises any downdraught.
The consequence is that the hottest air in the room - just above the radiator - is right by the weakest thermal link in the whole room and a lot of energy is lost immediately, through the glass. This is the primary reason why we have all been persuaded to invest in double- glazing over the years, to cut down these losses. After dark, we make matters worse by closing full length curtains across the windows and the radiator.
With underfloor heating, radiant energy from the floor which strikes the window glass is almost entirely reflected back into the room, and the only losses through the window are the simple losses caused by the room itself being warmer than outside.
- With radiators, the next hottest part
of the room is the ceiling. The losses here
are greater than with underfloor heating
because the temperature gradient through
the ceiling is larger.
- With radiators, the air in the room heats
the room surfaces and its furnishings. With
underfloor heating, the room surfaces and
furnishings heat the air. As a result, for
the same comfort level, it is usual to find
that underfloor heating users set the room
thermostat lower than with radiators, generally
by 1-3°C This reduces the amount of
heat energy lost through the walls and through
what are known as infiltration losses.
- Radiators need water which is more hotter
than underfloor heating, typically 70-80°C
compared with 45-65°C. As a result,
the heat energy lost from the pipework between
the boiler and each room is much lower with
underfloor heating than with radiators.
- As a result of using cooler water, underfloor heating can utilise water which is heated by solar energy, heat pumps, or waste hot water. The hot water which radiators need can only be obtained by burning fossil fuels. An underfloor heating system can keep a condensing boiler in its ultra-efficient condensing mode all of the time whereas, with radiators, a condensing boiler is only in condensing mode briefly - during warm up.