Hi,
It sounds like you have liquid propane entering the propane regulator. The liquid is changed to a gas there, and will require absorbing a lot of heat, thus cooling the regulator.
Try shutting off the propane at the tank. If you have another tank, use it. If not, then warm the regulator with your hands, and thaw it. Leaving the tank off, you will use up all the liquid propane in the hose by running the stove or water heater for a few minutes. Check the regulator again, and warm if required, use up ALL the propane between the shut off valve and regulator.
Once this line is 'empty' then you can open the propane tank slightly, so that the propane will not flow quickly out of the portable 300# tank (think the size of a home water heater). Check to see if the tank is marked 'liquid' and 'gas'. Your output must be on the 'gas' valve, not a liquid output valve. By opening only about 1/4 turn, if any liquid does come out, it will boil in the line going to the regulator, not inside the pressure regulator.
If you are hooked up to a gas output line, then my suggestion if the regulator keeps freezing is contact your gas supplier. They might be able to add some alcohol to the propane tank, or replace your regulator to solve this problem.
Propane systems normally work well until it is -20C, when the tank pressure is really low, and propane will actually 'freeze' in the tank. I suspect that some moisture is in the propane, and forming ice in the regulator. Adding alcohol will disperse this water, and prevent problems. If you find yourself in a really cold snap, the factory internal 7.5 or 5 gallon propane tanks might be warmer, and less likely to cause a problem.
However as the liquid propane in the tanks leaves, it must boil, and will require absorbing heat to maintain propane gas pressure in the tank, so it will keep flowing out. Warming the tanks might be required in really cold temps.
My buddy that flys hot air balloons has tank warming blankets for his 15 gallon propane tanks. IT is basically a very expensive heating pad, that wraps around the tanks, and pads them for passenger comfort, also is required to warm them to about 70F when it is below 50F outside, to raise the propane pressure in the tanks.
If you have an electric heater that you can place near the propane regulator, warming it to about 10C in that compartment will get rid of this problem. . . Or a 75 watt light bulb near the regulator will do the same thing.
Put a black trash bag over your propane tank. The sun will warm the bag and tank, raising it's internal pressure and bring the liquid temp up about 10C above the local air temp, and that will really help. AS long as the tank stays below around 40C, you will be fine warming it a bit. Above 50C, the pressure gets really high, so that is to be avoided. However reaching 50C+ (under the black trash bags) with your current 10C or less outside temps is unlikely. . .
Good luck,
Fred.
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