thermal mass for underfloor heating system

philip_2

hi
can anyone tell me what is the ideal depth of concrete to be placed over pipes of an underfloor heating system.

i realise that the greater the depth of concrete, the greater its thermal mass and hence storage ability,but,
this will effect the structures response time to the changes made in thermostat settings made by myself due to an unusually cold evening etc.

has anyone got any ideas on a happy medium.
i have been told that 3 inches is good laid over 2 inches of insulation.
these floors i have seen, they respond quick to thermostat changes and in fact the system is time controlled similar to a conventional heating system.
my concern is that alot more energy could be stored in a thicker concrete floor

GMcD

Radiant slab mass

It's my opinion that your are looking at things the wrong way. Thermal mass storage is a great energy saver, but, has a very slow response time to fast acting transient loads in a space. Therefore, the design effort must be spent reducing or eliminating those fast acting transient loads. If you have a well insulated house with very good to excellent thermal perfomance windows, you should not even notice the outdoor temperature swings from daytime to nightime anyway. The building envelope is meant to keep the climate variations outside the occupied space. Trying to make a slab system respond to fast acting transient loads is NOT the right way to do things.