I'm in western Arizona, so I hear you! My outside thermometer sensor needs batteries so I don't have an outdoor "min," but the indoor min the last three nights has been 39º, 3xº, and 36º. And that's at about 5' off the floor. Brrr! I think the actual outside lows have been around 6 degrees lower than that.
I mention it because I choose not to run heat overnight. But, I was toasty warm, thanks to my usual winter comforter with an extra down sleeping bag spread out inside the duvet cover. I also use a "head blanket" on the coldest nights, which is basically a small square of fleece draped lightly over my head (I don't sleep well with sleeping bags in the usual zipped up mummy position, and hats overnight bug me).
I realize that's not everyone's idea of fun, but I would be awake all night with the furnace kicking on and off. I have run my Wave 3 overnight once or twice (with appropriate ventilation), but I don't bother with that anymore. I DO try to make sure to set up camp with one of the big windows facing ESE. Since it's usually sunny when it's cold in the SW, this warms things up nicely in the morning (with a built in excuse not to get up before the crack of dawn
).
But okay, that doesn't address your furnace. I have never run mine, so I can't say whether it would normally keep you warm in these temps. But I will toss out some thoughts, in case one might help (hey, it's a technique
)
1) The oft-touted "Arctic foam" insulation in the Chinooks is a great concept. Fits all the nooks and crannies, keeps any condensation from forming on the inside of the shell, etc. BUT, I've had the walls down, and it's pretty darned thin. I've seen/read the same from other Chinookers, so I think it's typical.
2) Was it windy? An icy wind can really make a difference (in the brrrrr way).
3) Did you by any chance have anything blocking the intake vent that's on the front of the forward seat box (whether that be dinette or club chair)? It would be behind the passenger seat and I could see someone storing something there. The furnace needs that return air. A friend with a non-Chinook Class C had a huge furnace (like 24k btu), BUT, the RV mfgr had not put in the specified amount of venting. You could put the thermostat on 90º but the furnace would stop heating long before that, which we surmised was because it was not getting enough return air. The blower would still run, but you could hear the little "clink" and then the heat would stop coming. After a while of just blowing it would "clink" again and more heat would come, rinse repeat ad infinitum. I don't *know* that was the problem, it was just a guess. It would only get things up to around 65º with those short heating spurts (vs. full time blower).
As I said, I have not run the furnace. In my mind I could see it having trouble keeping up on a windy/cold night, but my guess would have it 50-ish in the living area and "don't sit down!" cold in the bathroom. Just a gut feeling but don't know for sure.
BG
PS: I would say 99% of campgrounds don't allow people to run generators between 10 p.m. and 6 a.m. so that's typical. (I'm one of those people who thinks listening to them from 6 a.m. to 10 p.m. is horrible, so I don't go to campgrounds anymore if I can help it. I wish they would change that at least in the nice little primitive forest service type campgrounds, so I could go back). But my views aside, not being able to run them overnight is pretty much normal in even the most generator friendly campgrounds.
PPS: If you find that your furnace is running normally and that's the best it can do, there are some other options, but I won't clutter up this post (any more than I already have
).