Well, I called the local service rep (its still under warranty) and he just left.. the problem was that the people that hooked up the propane tank apparently did not "set the gas pressure" on the heater, and this particular heater model is very finicky about gas pressure (I guess that's a good thing!). I have no idea what "setting the gas pressure on the heater" means. He says he fixed it so I'll give it a go tonight!