Anything will - if you apply enough heat. The best trick is to keep the water tank inside the cabin, and to keep the cabin above freezing.
Originally Posted by dbly1850
westyss build his cabin using a composite material that he says the manufacturer rates at R-7 per inch.
It looks like he used 2 inches or so thickness. He had a Mr. Buddy catalytic heater (those are 4k btu up to 18k btu I think), and it was too much so he replaced it with a 3k catalytic and even camping below -5C (+23F) it was "balmy" inside
That's pretty good, but still a long way from -20F. Turtle 4 crossed Siberia, in winter with a popup camper with a winter kit and a 20k btu diesel fired heater:
"Our Four Wheel Pop-Up Camper was unsuccessfully modified to handle the extreme cold of Siberia. It survived, and we survived, but in the process we again discovered the reality that despite its light weight and low profile, a pop-up camper is still a tent, best suited for temperate three-season camping. Once Spring arrived, the camper performed as expected, with the exception of annoying sidewall leaks during torrential downpours and high winds."
I have a 12k Surburban heater in my camper, and I would only recommend it for weekend trips unless you have a large propane tank or ready access to refills. Mine eats propane and battery amp*hours like candy. I have a 5 gallon built-in propane tank and using just the stove it lasts months. Stove and small Norcold 323 fridge, a month or so. Using the stove, fridge and heater - under a week.
For a pre-built camper, the Alaskan seems to have good cold-weather reviews, with the exception of the split door which doesn't do a good job of keeping in the heat between the upper and lower door sections.
I would think the best way to go with a pre-built would be a fiberglass unit like Bigfoot or DontPanic42's Casita. Bruce (DontPanic42) should be able to tell you how it fares in winter - though I find it very interesting that his post in this thread seems to steer you toward a Bigfoot and not toward a Casita... (Maybe he's got cold tootsies.)
The other problem is the water tank(s). Water is 8.4 lbs per gallon, so big tanks are bloody heavy. For a cold weather rig, you can't hang them outside and if you put them inside you not only give up space, but you raise the rig's Center of Gravity noticeably.
Some decades ago, I helped a buddy convert a school bus and we wrestled with these same issues. What we came up with was a raised sub-floor. We built a 12" raised sub-floor down either side of the cabin. Under that in front was a pair of 50 gallon, 10" thick fresh water tanks, and further to the rear, a similar set of grey and black tanks. This kept all the water inside the insulated cabin proper, while still keeping the CoG as low as possible without hanging the tanks below. Another benefit, was that by using the two tanks in a saddle configuration with a small 1/2" crossover to connect them, it kept the weight balanced and also prevented a bunch of side to side sloshing.
You can find pretty slim tanks if you look around:
This 110g tank that is only 9" tall catches my eye, though 33" wide might be a bit much:
For a -20F rig, I might be tempted to start with a standard delivery box and line it with a couple three inches of that stuff that westyss used, stick the water tanks under sub-floors down either side, with an Espar diesel hydronic for heat, and (as haven said) the hot water lines run along side the water tanks under the sub-floor.
An added benefit to having the water tanks (and/or batteries) inside the cabin is that they constitute a pretty hefty thermal mass - which is great in the winter...not so great in the summer.
Last edited by dwh; 12-02-2010 at 01:27 AM.
Current: 76 E-250, bubble-top, self-contained|couple of old Yamaha enduros
Previous wheelers: 41 Willys|78 FJ40|78 Bronco|84 Bronco|74 Ramcharger|78 Ramcharger|79 D150 PowerWagon|77 D100|79 D400 dually, converted to 4WD, utility bed, 10' Lance|75 Westy|69 Scout, RHD|bunch of others|bunch of bikes|couple of boats|couple of motorhomes|blah blah|so what|not my idea|just doin' what I'm told|wank wank|this space for rent|candy is dandy|but liquor is quicker