Hi all,

I have a small cabin about 570 sq ft. I have placed staple up 1/2 pex until AL sheets under the floor, then AL-foam-AL insluation below it such there is a 1-3 inch air gap.  Further the cabin has skirting around the bottom. The plan is to use solar collectors and 800gal storage tank as the heat source, but I don't have it in place yet.  So I'm considering tapping into my electric hot water heater for a temp/backup source of heat. I'm only concerned about keeping things warm enough to prevent freezing in the cabin, as when I'm there I also have a small LPG heater. Here are the questions!  1) Is this pratical? 2) I used O2 barrier pex, any problems with putting potable water in it?  Or do I need to put a heat exchanger between the floor loops and the hot water heater? We don't drink the water its only for bathing, flushing, etc.  

Thanks in advance for comments and suggestions

Alan