Retrofit Underfloor Heating

[Englishman in Ankara]

I am planning to install RUH (topic!) under the floor of our kitchen (the system will be fixed to the basement ceiling). The floor is 6-8 inch thick reinforced concrete.

I need to know the following:

1) Should I space the heating pipes the same as if they were just under the surface (as in new-build)

2) what thickness of insulation (rockwool?) should I install?

3) Does anyone know where I can find a (comprehensive?) guide to such systems on the 'net?

Thanks for all your (anticipated!) help... Abdullah Eyles (back again!) Ankara, Turkey

[Mike]

I think I would say don't bother. The time lag on this will be days.

However if you do it then the standard spacing is fine, and one can never have enough Rockwool or other insulator.

[BigWallop]

Trying to heat a floor that it concrete of that thickness would be mean a huge heating output for a boiler. The heating would have to be constantly on for days, if not weeks, for the heat to be felt through the top surface of the floor. Romans used this method of heating stone floors, but they had slaves to stock huge fires under them.

Are you heating the basement or the floor of the kitchen?

You should build a timber sub-floor on top of the concrete one. You might find that this alone will increase the ambient temperature in the room. If the room still needs extra heating, then placing the pipework for a heating system between the timber battens would make it much more efficient at transfering the heat to the room.

A layer of moisture barrier membrane may be all that you need under the timber battens of a sub-floor. The wooden battens used for a timber sub-floor could be just slightly thicker than the pipework used on the heating system. Enough to stop the movement of the floor board touching the pipes is enough.

Thanks for all your (anticipated!) help...