We've had a run of cold here too. As I said we spent Saturday night looking for a frozen heat pipe (no heat upstairs all day). Finally found it and thawed it with heat guns. We've been here for almost 20 years and that has never happened before. Time for some anti-freeze.
Some of the local plumbers here are conscienceless! Initially I called one to come (because the pipe was buried in a front wall) and thaw the pipe because I heard most have one of those electric pipe heater thingys, like a welder. You don't have to actually locate the frozen spot. They have a $150 service call fee plus whatever it takes. I say ok. How much could it be, right? Well, the guy shows up and tells me that for $480 (plus the $150 fee) he will point a salamander heater at the front of the house for an hour! No guarantees! If after one hour it doesn't work, I'm out the $630! Are you kidding me??!! When it's 8 degrees out, can you imagine how long it will take to heat the house enough for the heat to penetrate the siding, sheathing, insulation then reach the pipe and thaw it?? I was SO angry!! It cost me $150 for him to tell me that. Some people just prey on the weak and vulnerable with no conscience. Shameful. Ok, rant over...
