Frozen Pipes

[Pineedles]

Step1
Frozen hydronic (hot-water) heating pipes present problems best addressed by a plumber. Your best bet in the meantime is to turn off the heating system's water supply, which will prevent a major flood in the event that a burst pipe thaws. Do not turn off the boiler if you have more than one heating zone on your thermostat, since another zone may be working.
Step2
Relieve any excess pressure in the system. Follow the same procedure you would to drain a waterlogged expansion tank: Shut the valve to the expansion tank. Attach a garden hose to the hose bib on the tank and extend the other end to a drain. Open the hose bib to drain the tank. Then close the hose bib and open the valve to the tank.

Looking at several sites they all say to avoid extreme heating sources such as a torch or other such devices. One site mentioned tenting the inside and if necessary the outside wall and tryng to create a "warm zone" in the enclosed area.