Driftless SW Wisconsin | Marc, If you put the tubing under only part of a shop floor - maybe where you will be working occasionally - but not under the whole floor is there likely to be a problem with cracking the concrete between the heated and unheated sections due to thermal expansion? I have heard of heating zones with tubes. This is a currently uninsulated gravel floor shop that needs concrete at some time in the near future. Just looking for a bit of help from the floor with an outdoor wood furnace as the likely heat source so I can pour the btu's on when used occasionally. Are these tubes OK with antifreeze in the dead of winter if not kept heated continuously? Jim at Dawn |