Nathan,
Sounds like you are looking for a cold weather solution. There are all kinds of ideas out there. The first solution is your tent, you want to go with passive solutions before you start with active systems like the Zodi heater. For example, no one can sleep with a Zodi heater on.
Winter tents are double walled and sometimes made with insulation. You want to limit the space inside the tent, more space, more to heat. A smaller tent works best for passive heat because of this. Next, look is at the base, this is where most your heat is lost. I had a designer from Canada tell me how he was going to build a rooftent with an alloy base for strength. Bad idea, he would kill people, he was designing a perfect heat sink. An insulated base is the first thing to look for. Second is your roof, you don't want it too high, if it is insulated to ward off condensation, bonus. A second side wall will work much better especially if you are in windy areas. I don't know if it is true but it seems like the higher you go the easier it is for wind to get through the fabric.
If you have a folding fabric tent it is more of a challenge but you can make these tents perform pretty well. I have been in many blizzards with this style of tent. First rule, a small one works better. You will want to insulate the ridge poles for condensation. You have probably noticed that the mattress you use doesn't seems so nice. Foam gets hard so you need more of it, memory foam is the worst in the cold. An ensolite pad helps or I've been using a special mesh under the foam that really works well. See if your manufacturer offers a "winter hood", they help in the wind. If I'm in really nasty conditions, I will hang a couple candle lanterns up in the ceiling if I'm using a tent with a high ridge. Yes, it isn't recommended i.e dangerous, I'm talking about real cold now.
Next thing is active systems. The Zodi heater is the best of the lot. It has shortcomings though, it has a lot of parts, really noisy and loses a lot of heat before it gets to you. I will use my Zodi to heat the tent while I'm reading and then shut it off to sleep, it is nice to know it is there if I really need it. I don't recommend a catalytic heater, almost had a friend die on a boat that was all buttoned up and he left his heater on. I just don't trust them, yes it is strictly a personal opinion and probably not backed up by fact. The other reason is that they emit CO2 and water vapor, both can be a problem, if there is too much CO2 and not enough oxygen, then the heater produces CO, carbon monoxide, very bad. The water vapor also isn't good, we design tents to breathe and let out the water vapor from people, you introduce more water vapor and you will get condensation. Dry is warm, wet is cold, condensation is bad and cold.
I have a lot of guys that go out in conditions that seem to me unbelievable. One fellow in particular goes out in 40 degrees below, he swears by a $20 12 volt electric blanket he got at Wall Mart, that fine expedition outfitter. I don't have a second battery so I've never tried it. Another customer, spent a winter in high elevation New Mexico setting up all the 911 maps to the outlying ranches. He swears by a 12 volt heated mattress pad. The best is we have an outdoor photographer, builds a bonfire and rolls a boulder in it. Once it is really hot, he rolls it onto a piece of plywood, cover with aluminum foil, and boost up into the tent. Says it works well in the Arctic, really, he films Polar Bears.
Hope this helps, I know I can get a little preachy but it is a safety thing. Rooftop tents really hit their stride in cold conditions. I go out in conditions that I would have never have gone out in without one. One time, I thought it was a little cold, but didn't realize how cold until I went to start my truck in the morning. Battery frozen solid, absolutely no power, had to warm it up to start the truck, then I was cold.
Rich @ AutoHome
www.AutoHomeUS.com
