In my basement I have a 1/2" copper water pipe that goes to an outdoor faucet for a garden hose/sprinkler. This line has its own shutoff, so during the winter it is turned off and emptied.
The problem is that about 15 feet from the exterior wall the pipe reaches a critical junction in the water lines. If it gets really cold outside, below 10F, the pipe will transmit the cold all the way to this junction and freeze it and then the water supply to the whole house is cut off. I have used heat tapes, propane torches etc to solve the problem when it crops up, which is once every 5 years or so.
However, what I would really like to do is install a passive (non-energy-using) solution to get rid of the problem permanently.
What I envision doing is installing some kind of thermal isolator in the line to the faucet. So, for example, if I replaced say a 12" length of the pipe with a PVC pipe it would probably solve the problem because the PVC will not conduct the cold nearly so well as the copper, so basically the PVC should "thermally isolate" the faucet. That's my theory at least. Another option would be to create a removable link or section in the pipe. The section would be removed/disconnected in the winter, then connected back up again in the spring.
Is there a way to do either of these things?