burying copper radiant in cement

[jay1970]

Hi - we have a 1950s Eichler house in North California. Copper radiant pipes embeded in concrete. Everything works fine and beautifully. Just got some remodeling done and because of that we had to excavate the manifold area (and break all pipes in process). Everything has been repaired now with a great new manifold and system has been tested etc. Getting ready to pour new cement over the excavated area (about 3 Ft by 6 Ft). QUESTION: Which option is better:
Option 1: Fill dirt up to 1 inch below the radiant pipes, put in 2 inches of gravel on top of dirt so that copper pipes are 1 inch BELOW gravel, pour cement on top of gravel.
Option 2: Fill dirt up to radiant pipes (but not covering the pipes, pour cement on top of pipes (so that pipes will actually be embedded in concrete)?

Also if Option 1, what gravel will be best?

Thanks!

 

[COLIN LITTLER]

Dirt to the top of the pipes, then concrete, to allow for expansion of the copper. Gravel is not a great conductor of heat, but would be good below the cpper to reduce heat loss.

 

[dave_39]

I would not recommend concrete to be in contact with the copper as there could be a chemical reaction between the two.