most underfloor heating systems are either warm water (wet) systems
electric (dry) systems.
For wet systems, pipes are
buried in screed, or run underneath the floor surface. Wet underfloor
heating systems operate by heat transferring from the water passing
through the pipe directly into the floor. Because the whole area of the floor
is warm, it heats the room more evenly.
Unlike radiators, underfloor heating systems do not need
to run at high temperatures. Heat imparted to the floor is released across a
large area rather than the relatively small and focussed area of a radiator.
As such, UFH systems do not need to operate at such high temperatures.
Typically, the temperature of the water in an underfloor heating system pipe is 45 –
65oC (compare this to approximately 80oC flow
and surface temperature of a radiator system) warming the floor to a
temperature of 25 – 28oC, which is comfortable to walk on.
For Dry Systems, the principle is the same.
The difference is that instead of imparting heat from water passing through a
pipe, you use an electric heating element as the heat source.