Not very likely.
Propane still can vaporize down to - 44 F

dcarch

Register a complaint where you bought the propane. They may have moisture in there tank.
John

That's why I made mention of the moisture. probably at the regulator or in the line.
Dave

Really dump question:

May be the tank is empty?

dcarch

That was my first thought. Maybe I had a leak. I just filled it 6 days ago. Nope, it's full. I pulled the lines, brought them in the house next to the wood stove. Took off the trap, bone dry. Blew out the lines. Put it all back together. It's working for now. I just didn't see any water in the lines. I swear, it acted like the propane froze. The regulated was all iced up I couldn't tell what it was. So, I'll see if it's fixed. I'm suspicious though. Maybe the heater is sucking air? I just think it's a coincidence this happened during our freeze.
Dave

Really stupid question but,

Are you using Propane or LPG (often reffered to as "Propane")?

http://en.wikipedia.org/wiki/Liquified_petroleum_gas

I had a look around earlier today on the net because my propane has never frozen up, but I believe in winter they deliver propane that has additives that absorbs the water in the tank (methanol?)Also it is 100% propane.

Found a good thread on an RV forum.

They are talking about "Propane" and LPG.

Read all 3 pages, interesting stuff!

Here is a link that might be useful: RV forum

That's a very good question. The poster that suggested hot water on the regulator sounds exactly like my problem. The last time this happened, I poured hot water on the regulator and it started again.
I'll have to somehow blow it out or just replace it and then find out if my distributor is getting water in somehow.
I don't believe it's the butane/propane mix problem, as the tank is near full, so not much propane has burned off.
Sounds like water or the regulator vent frosting up.
Thanks
Dave