Our ability to camp 365 days a year largely depends on the options how to keep our (rooftop or other) tents warm. Well, sleeping bags intended for below -30 temperatures do exist, but freezing your nose and face off if they’re protruding from the sleeping bag isn’t really the perfect idea of nighttime comfort. And being wrapped up in your mummy-bag doesn’t really leave space to do anything but sleep while in the tent. So what are the options of improving tent-life quality in cold places?
Active heating inside the tent
People usually seek for some cheap and simple solution, but it’s not so easy to find them. Gas based heaters are way too dangerous or impractical to be used in a tent, for several reasons. First, there is a risk of CO poisoning (however small it may be), second, there’s a risk of fire, and third, obtaining adequate amounts of gas for a full night’s heating is either expensive, or troublesome.
Getting an electric blanket is a somewhat smarter solution, that will significantly increase your comfort level. And if you have secondary battery in your vehicle to supply adequate amounts of electricity for the night, you have nothing to worry about. However, it’s a compromise solution, that doesn’t really influence the air temperature in the tent, it just adds extra warmth to your body.
So is there a more effective solution?
Yes there is! I used the term Webasto by the name of the oldest and most famous company manufacturing these gasoline/diesel vehicle heaters, but you don’t have to pay for the expensive Webasto models. You can also get a Russian Planar, or some real cheap Chinese alternatives, and they’ll probably work just as well. So how can these help heat up your tent?
Nowadays it seems very popular to buy these in a ready made, boxed package containing the heater, a fuel tank and a battery, so that it needs no connection with the car whatsoever. You just load the box when you’re packing, take it out and place it outside when you need the heating, stick in the hose, turn it on and there you go!
However, I must say that I don’t really like this concept. I find it not very convenient since it’s quite a bulky box that you have to find a place to store somewhere, it has some extra components that are not really necessary (fuel tank and battery, since the internal tank and battery of the vehicle can be used), and you still have to find a way to recharge the extra battery in the box. So it means more cables protruding everywhere (as well as checking if the small fuel tank has enough fuel every time). And in the end, stuff left outside overnight can easily get stolen.
How should it be used instead?
Well, the most elegant way to provide a warm air heater for your tent is certainly to install it permanently into your vehicle, and transport the hot air to your tent with a hose. When it uses the electric and fuel resources already present in the car, the heater body itself is small enough to be fitted in some corner of your trunk using an insignificant amount of space. You just need to make sure that it has enough space to “breathe” and suck in cold air when it’s active (meaning don’t completely bury it under stuff, or al least clear the space around it before turning it on).
It may take some thinking to find the ideal spot for installing it, because it will be necessary to drill three small holes through the trunk floor – one to suck in the air necessary for the burner, second to stick the exhaust out, and third, to push through the fuel supply. All other connections are made on the inside of the vehicle.
The secondary battery
Having a dual battery system is a smart thing for any expedition vehicle, regardless if it has a hot air heater or not. There are so many electric gadgets to supply during wild camping (fridge, laptops, phones, cameras, etc.), that running them all on your main engine battery brings you into high risk of having it depleted and remaining stranded somewhere when you least expect it.
If you connect the two batteries with a switch that controls the recharging of both from the alternator, and add a solar panel and a solar panel controller to recharge the secondary battery by solar power when the engine is not running, you get quite a usable wild camping electric energy supply, that has a theoretically endless autonomy (depending on the ratio of your usage vs. strength of the solar panel, of course).
How does heating the tent really work?
It’s actually simple. All you have to do is connect a hose which is long enough, stick it out through the window (preferably with a custom carved insert with a tight hole to prevent precipitation from getting into the vehicle during the night), stick it into the tent, and do the same with the electric cables of the controller, and the thermometer. The controller is used to turn the heating on or off, set the desired temperature, or program the time to turn on or switch off. So you can either heat the tent full time, or heat it up just temporarely to fall asleep and wake up, relying on your warm blankets or sleeping bags in the meantime.
The effect of such a solution is really remarkable – in only three minutes after turning it on, the tent temperature will rise by some 15 degrees, and in ten minutes it will easily be 25 degrees higher then the outside temperature. So you can sleep in true room comfort even in sub zero temperatures!
How much does it consume?
The fuel consumption of such a system is so low that you absolutely don’t have anything to be concerned about. How much fuel it will actually consume over night will depend on the outside temperature, as well as the desired temperature that you have set by the controller – the bigger the temperature difference, the more fuel it will have to burn. But even in the coldest and longest nights it should not exceed a few litres for the entire night (you certainly won’t notice that the fuel gauge in your instrument panel has moved).
Electrical consumption is relatively low, since it uses electricity only to power the fan. So it shouldn’t be capable of depleting more than 1/4 of the capacity of a 100 Ah battery during one night.