Ouch. Didn't see this thread yesterday.
Unfortunately the breaks usually don't happen until the ice starts to thaw. With the blow dryer option I would start closest to where the water has some place to run to (either the open faucet or junction with the main). If you start in the middle of a frozen spot it will have no place to go but to put pressure on the pipe.
Hmmm, so with the plastic pipe the heat from the house and the heat from the tape is not conducting through the entire system. That is a disadvantage of PVC I'd not thought of before. We left the house without heat for 2 weeks over Christmas. Only one section for about 12 feet is PVC all the rest is galvanized. We did put a space heater in the well room, but other than that nothing. Granted I've probably got 10 times the thermal mass of a normal house, but despite a nasty cold snap, all was ok upon return. I might not use PVC in the future just for this reason.
How is the cold air getting into the crawl space? Could you put a space heater into the crawl space? It only has to heat it to 33 degrees.
In a nutshell Horseman, the crawl space is only protected from the "outside" by thin aluminium siding and nothing more than that. The wind blows, and it does here living in a valley, the siding comes off and you have an instant wind tunnel. In the past, I have used a Salamander to thaw out the kitchen pipes when they have frozen due to us forgetting to let the water drip/run. That has always only taken about 1/2 hour to do and the heat was being focused on the exact spot where the pipes were freezing on those occasions.
Whatever I get, is going to have heat an exposed area of 1152 square feet X an average of 3' high. I honestly don't know if a salamander will even do that, without spending an indecent amount of money (that I frankly don't have) to do it.
I spent most of last winter living in my camper while I was working on a gas fired power plant in northern Illinois. The temperature got down to as low as -31° with MANY nights and days below 0°. I had my water hose laying on the ground during this time and never had it freeze up. I did have a problem once with the hydrant where it came out of the ground because I didn't have it insulated well enough. I was able to thaw it out with a hair dryer but I ruined my heat tape because I got the wire (tape) to hot. I couldn't see it in the dark and the wind was screaming and I was shivering and cussing. Long story short, I got the next to last piece of heat tape in Sterling, IL and redid it the right way. I prefer the tape that has the thermostat exposed to the open air with a light that comes on to show that it's working. These will come on when the ambient temperature is around 40° and it's very easy to tell if they're working ..........no light and the temp is below freezing, bad heat tape.
The more I think about it, the more convinced I am that the heat tape has failed as that runs for all but around 4' of the main line. My suspicions are heightened by the fact that we had colder temps here about a week ago along with wind and didn't have a problem then. Seems like this happened, quite literally, over night.
Right now, the house is being kept at an average of 78 F with all of the cabinet doors and taps/.faucets open and nothing has changed. There has't even been so much as a hint that something is thawing out. I can't believe that having such a high and constant temperature hasn't done something, especially as the temp got up to a little over 30 yesterday. With 30 degree temps, no wind and a working heat tape - whatever was frozen should have thawed out enough to allow the water to at least drip. Hell we had one instance where the cold water froze and then came back on when the outside temp was only 20 something.
Sorry guys, this is I guess taking a toll on me. I have never not been able to fix a problem around the house or, at least identify a problem so it could be fixed. Add to that the inability to shower and flush a toilet, well, my sense of humor is running very low.
