Last week my wife and I closed on our new home. Upon taking possession last Thursday, we found that there were frozen pipes despite the furnace being on. We have water in one bathroom, but nowhere else in the house. I figured that heating up the home would solve the problem and turned up the temperature. On Friday there was running water around the home. When we stopped by on Saturday, the pipes were frozen again - despite the heat remaining on. We moved in on Sunday and I had some knowledgable friends and relatives look around to see if they could figure it out. We got plenty of "hit it with a hair dryer" and "leave your cabinets open", but the problem is I don't know exactly where the frozen pipe may be but I suspect it is under the house somewhere.
I found the main shutoff for the water and started punching holes in the wall. The plumbing I see at the shutoff area is as follows:
Supply line -> Shutoff -> Pipe A -> Shutoff -> Pipe B
Pipe A is the primary house line. Pipe B is for the outside spigot.
Pipe A splits almost immediately inside the wall, one line running directly into the bathroom that has water and the other running straight down to the floor and presumably into the slab where it wanders into the rest of the house. We've attempted applying a heat gun directly to the water shutoff area and I've had a space heater running in that closet for a couple of days with no results. Not even a drip anywhere else in the house. The shutoff is located in the back wall of a closet near an exterior wall but the pipe doesn't seem to be frozen above ground (it is not significantly colder to the touch than the obviously functional pipes).
I'm not entirely sure how the pipe could become and remain frozen under a house with plenty of heat, but it happened. Temperatures have bounced around between 0 and 20 degrees for the past few days, but indoor temperatures have been pretty steady at around 75 degrees.
So, any thoughts on how to thaw frozen pipes buried in a slab foundation? It is getting awfully tiresome having to run over to friends houses every day for a shower and I don't think we're going to get a thaw around here immediately - global warming or not.