firing up my RMH in sub zero temps

[yigenuren]

Soooo, winter has come roaring in here very suddenly and I'm still a long way from being finished with cobbing everything in. I'm thinking of mixing the stuff at home and hauling it out there to put on the heater (bit by bit, my Jetta will only hold so much) but I want to fire the thing up each time so that it will dry/thaw out instead of freezing.
I've made the burn areas all out of firebrick except for the heat riser which is steel. Will the extreme changes in temperature cause cracks or other damage? I'd like to know so that I can try to finish this thing!

[canyon]

We built a rocket mass heater in a workshop up here in AK about three weeks ago in freezing temps. It is important to be firing it during the process so it doesn't freeze and break apart. Little by little will be fine as long as you keep firing the thing. You might consider an old blanket or two to drape over it when you aren't there working on it. I like to keep a few small containers of water around the area at different heights and locations to give me a clue as to where in the room it is freezing hard.