Nat. gas radiant garage heater

Radguyman

I've got a long ceiling hung natural gas garage heater that I've been having problems with this winter. When the temperature is above -20 Celsius or so, the heater works great. When it's below that (maybe this is irrelevant, but it seems to be when it acts up the most), the heater will start running, ignite the gas, warm up for between 30 seconds and 15 minutes then while still running it will just stop burning. The fan keeps running until the power is shut off (because the thermostat is still telling the heater to keep heating), but the gas just stops burning. Help! What do I do?! Is it possible that the problem is with the amount of gas pressure being supplied to the heater, or is it likely another issue? Thanks guys!