Under what conditions does heating a tent artificially make objective sense?

Question

My question is motivated by the earlier question How To Quickly Warm A Tent, which generated a lot of interest, and one of the best comments ever on TGO:

All I could think about after reading your other half's post, was what my wife would think, if after a night of her puking, my primary concern was about her letting in the cold air.

In decades of backpacking, we have never even considered warming the tent with anything but two 100 watt heaters, i.e., ourselves. Our backpacking is confined to spring through fall, in the Sierra or Rockies, often above the snow line. It doesn't get super cold -- the coldest we have ever experienced is 4 degrees F (minus 15.5 degrees Celsius), and we each regretted not having an extra sleeping pad. However, our water bottles have often frozen solid (outside the tent).

So my question is: Can someone sketch the conditions under which an artificial device to heat a tent makes objective sense, as measured by, e.g. expedition practice? By expedition practice, I mean expeditions in extreme cold, for example but not limited to, polar regions and very high altitude. (Exclude tents for car camping, tarps, and three sided set-ups.)

The linked question does not provide an answer to this question. The accepted answer to the linked question says:

Basically you should never find yourself in such a situation under normal circumstances.

with which I agree. The kicker is normal circumstances, and I am asking about circumstances which are not normal or are on the fringe of normality.

Answer 1

This question seems dead, but I felt I had to chime in here. As a specialist expeditioner of Arctic regions as a photographer, sometimes heating a tent becomes a necessity over time. Damp boot liners and gloves can give you frostbite in a hurry under certain conditions, and I have found it one of the most critical things to get them dry for a few hours in front of a Little buddy heater or over a propane cookstove in my heated Trango.

In addition, there are very different missions in expeditions. Not all of them are designed to get to someplace and back out as quickly as possible-- many are designed to allow one to stay out in a place as long as logistically possible, as in science/research, photography/filmmaking. The ability to make a tent into a livable place under Arctic fall-spring conditions makes the difference between staying in a place for months versus weeks or days. Yes, for a lot of larger productions, we have larger tents and more gear-carrying capacity, but there are most certainly lots of conditions under which it makes sense to get there by snowmachine, or under non-motorized forms of transport, like skis (i.e. snowkiting) dogteams, or even kayaks. Under these types of expeditions, you can carry more stuff because you're dragging a pulk or a sled or qamutik, and you necessarily need all that gear because of the conditions and the length of stay.

In addition, across the Arctic, indigenous peoples heat their portable shelters, tents etc, for the huge advantages it gives you for drying things, for comfort, and for simply livability, especially for subsistence hunting or herding. The entire notion of treating time in the outdoors in the Arctic and sub-Arctic as an almost-survival situation is a colonial perspective-- it means that this place is not your home and you are foreign to it. This is not a judgement on those who are not indigenous, but meant to help many understand that these things are cultural attitudes and highly variable.

Heat your tent if you find it necessary for livability, but be careful to do it right. Open flames are dangerous, and carbon monoxide poisoning is too. It's a matter of learning to travel with more durable and heavy gear, but less fancy hi-tech gear-- you will pick and choose your specific gear setup, and learn to account for the weight and bulk of fuel. Look to local peoples for how they transport themselves and how they camp-- that's where all the real knowledge is, and with it a deeper understanding and connection to the land.

Answer 2

The general rule I use is if your tent needs to be heated to be comfortable, then you're "doing it wrong" and should have gotten a better tent. There isn't really any weather (especially backpacking, where weight matters more than it does when unpacking from a car) where the correct tent and sleeping equipment can't be made pretty cozy.

However, "I told you so" is not gonna keep you warm. So really the only time that you would artificially heat a tent, is when you have the wrong tent. The best way to go about it is old school bed warmers.

Take a rock, place it in the fire, when it gets hot enough, move it to the tent. Make sure to place it on something that can take the heat. It wasn't uncommon for bed warmers to be made of metal, so you should be OK placing your hot rocks on something similar. Try to keep it off the tent walls and floor. Other "poly-what's-it" materials would similarly melt away. But putting rocks in your frying pan should work ok.

Depending on your sleeping bag you might even be able to place them right in the bag with you (don't actually touch them).

Bed Warmers

Answer 3

I would say there really aren't any. Even a hypothermia patient would get wrapped in a hypo wrap and the stove would be used to boil water to go into Nalgene bottles.

The problems with running a heater inside of a tent include,

• Catching the tent on fire.
• Carbon monoxide poisoning.

There are heaters that are meant for use inside tents, but you are asking about backpacking and so their weight rules them out.

If you want to use your stove to warm up inside a tent, boil water and use that in hot water bottles.

Answer 4

Assuming you do not count putting a hot water bottle in a sleeping bag as heating a tent (although it will eventually heat the tent), it only makes sense to intentionally heat a back packing tent if three conditions are met.

1. You need extra heat. There is no reason to heat a tent if it is already hot outside

2. You have a form of heat for which the risks from the heating process are less than the risks from the cold. Heat involving combustion often involve flames and tents, back packing gear, and backpackers do not generally react well to flames. Heated rocks can explode and/or melt tents and burn backpackers. With heated water there is a chance of a leak result in hot water (which will eventually become cold water) soaking gear.

3. You lack any form of insulation. Typically in cold conditions a backpacker will be between insulating layers. A sleeping pad on the bottom and a sleeping bag on the top. In extreme conditions there may be additional layers inside and outside the sleeping bag. There is then a large pocket of air and a tent/fly. The tent material essentially provides no insulation.

Under normal heat loss scenarios, you want to put the heat source between you and the insulation and not the insulation between you and the heat source. As the assumption is that heating a tent requires the heat source to be outside the insulation, heating the tent only makes senses if there is no insulation.

Answer 5

Many adventurers have a stove on them, though not necessarily for the purpose you describe.

From "Obtaining Water from Snow and Ice" by Dryad (who offer bushcraft and wilderness courses:

Most mountaineers, and explorers travelling in cold environments, carry modern stoves which use liquid fuels such as Unleaded Petrol, Propane Gas, or Coleman fuel in order to melt Snow.

So you're in an arctic tundra or on top of a mountain, and you are in a tent with a stove on hand. Is using the stove to heat the tent a good idea? That depends...

• Some tents are designed to be used with heaters. But,

• The tent is not going to be nearly as good at holding in heat as your sleeping bag. And if you brought the appropriate bag, you should not need a heater.

• Using the stove uses up your fuel. So either you are dooming yourself to not have enough fuel to melt the water you need, or you are bringing extra fuel - a lot extra, way more than it takes to melt some snow. Extra fuel is extra weight. Weight is usually kept to a minimum.

• One of the specific stoves I link below says it uses 2 liters of fuel for 8 hours of use. I'm not sure how that compares to others, but for that particular stove heating would cost you 2kg (~4 pounds) per night heated. That is nearly 30 pounds per week, not including the stove's weight.

Warning: There are potential dangers with heating your tent, even if you use stoves and tents that were designed to be used together. You need to guarantee that you do not catch your tent on fire, and also that you do vent the gases well enough that you do not poison yourself. Even if you account for that, you need to be vigilant, as a blockage in your vent (eg: snow) could kill you. (credit @Gabriel C. for safety suggestion)

I think the only three situations where heating the tent make sense (and only 2 of them are a necessity) are:

1. if you can, and doing so would be easier and make you more comfortable. This is more a want, a luxury, than a need.

2. if you are in a place which is so ridiculously, brutally, insanely cold that it is difficult to get warm enough without heating. I'm not even sure if this would be a thing, but I'm raising it as a possibility. The people who have the experience to confirm or deny this would be very few and far between.

3. if you are improperly prepared. Essentially, you are in an urgent, or even emergency, situation.

It makes sense when you are treating yourself to luxuries.

Maybe you were willing to haul the extra fuel. Maybe you have a large party or hired porters. Maybe you brought solar panels for your devices or a passive solar heater (both of these things some people do bring on the type of hike you described).

Whatever the reason is that you are able, assuming you are able, now you don't want to cover your head at night, you want to get out of your bag in the morning to the luxury of warm air, and you want a place to retreat to in order to relax in a warm place when it is cold outside.

Remember, when people ask "What do I need or not need to bring on such and such a trip?" we keep telling them "Whatever you are comfortable leaving behind, do without, and bring the rest if you are willing to pack the weight." Well, some people refuse to car camp or even to RV camp if they cannot bring their hair drier, so I imagine there are people who would desire the luxury of a warm tent, and for them heating the tent makes sense.

If you say otherwise, I will tell you that having a tent at all is not necessary. ;)

In case you want this luxury, here are some random links to items made just for this which I found with a quick Google search:

1. A 29 pound oil stove. Fuel use is listed as 8 hours per 2 liters. If your group wants to carry the extra 40+ pounds, enjoy.

2. This winter tent on Amazon even comes with a chimney and a stove! More than 70 pounds though, not including fuel.

3. An all-weather tent with option for additional heater which is sold separately.

Because it's a beyond-frigid -135 degrees out!

Record low temperatures on Earth in the coldest places have gotten to approximately -135F (-95C)! I assume very few people go to the spots where this has happened, but there are some very brave adventurers out there who might want to experience the coldest our planet has to offer.

So you say, "But I could build a snow cave, and I could do it the correct way so that it would be very much warmer inside!" Perhaps. And the common claim is that no matter how bad it gets outside, if you've done your snow cave correctly you can enjoy a balmy 32F (0C) inside. But would that still hold true if it's a freaking -135 degrees out??? I don't know, but I would not bet my life on it. This might deserve another question.

Let's say that the snow cave can come up to freezing temperature though. Now what? You've made the cave when it's perhaps only -50 or -100 out. Will your body heat raise the temperature fast enough for you? Maybe. If not, you might say "I'll just use something to help with the warming a little bit, maybe crack open a hand warmer to help raise the temp until it gets there." But now we're back to warming the "tent". "Oh right, so I'll just keep it in my pocket so it warms me." Fine, you're not technically warming it, you're warming yourself, but that's a fine line. I could also say that the mere prospect of making a snow cave to raise the temperature is itself a case of warming your tent.

But what if you get there and find that the material is not conducive to creating a snow cave? Or, someone might complain saying "I asked about a tent, not a cave." (though I could say "Just put your tent inside the cave.")...

So let's leave the cave idea behind for a moment and talk again about just a normal tent on its own. So you want to try to survive, comfortably, one of Earth's record cold nights in a tent. Sometimes people double-up on bags. So let's say you get the extreme coldest rated bag available on the market, two of them actually so you can stack them, and a good bivy bag to go over the dual sleeping bags. And dress yourself very warmly, as warm as is reasonable for sleeping. Now you're in Antarctica during its winter, where it is literally night time all day long for days straight. Can your warm setup keep you warm enough through that night, where it gets down below -100F or -90C at least once?

In the super frigid arctic scenario so far, maybe you could be comfortable with the ridiculous setup in the previous paragraph. I'm not sold on the idea that you could though. At this extreme, I don't think conventional estimations would be very accurate. But even if you could be comfortable inside your sleeping bag, it might be easier at this point to warm your tent a little. At that huge a temp differential, a little bit of heating will go a long way. Just remember to keep your heater itself warm enough that you can start it. Still, at this point it might be easier to do a little bit of heating anyway than to just keep piling on more layers. Also, eventually you will probably want to come out of those sleeping bags and move around your tent during this Antarctic winter.

Update

I have found supposed evidence of sleeping bags that are rated down to the record temperature, but I found them on forums where people were expressing skepticism about them. I'm not sold on that.

After a quick search for coldest sleeping bag, I found some that seem more trustable rated at -40F and -60F. Here is one, and another. They are the body form-fitting type, so I'm not sure how well they would stack. But if you could fit one into another thing that was -40F or -60F, even if I was wearing a good coat and multiple other good layers under that, and had a bivy over the dual bags, I still would not want to trust my life to that at -135F if it was my first time trying to endure that. I would bring body warmers to use inside the bag for a short stay, but for a longer stay where they won't last long enough, I think I would want something to warm the tent. However, that then raises other considerations, such as what do you warm the tent with since many fuels might freeze at that temp? Is it safe to bring a tank of propane on such a trip? The jury is out on this one, but I still believe it fits your criteria.

And I just realized another point when reading about obstacles that cold weather sleeping bag makers need to consider: the mere act of breathing in the very cold air from outside your bag. You cannot just keep rebreathing the same air again and again; it needs to circulate. At -50 maybe you can get away with minimal air heating by clever design that exchanges heat during air circulation, but at -135 even a lot of heat-exchanging with the warm air that's leaving the bag will still leave the air very cold as you breathe it in. Heating the tent will greatly help here and might be your best choice.

So, for someone wanting to set the world record for camping out in the coldest weather, every little bit helps and heating the tent would make objective sense.

Emergency! You're not fully prepared!

For whatever reason, you are not fully prepared. You are using everything you've got, and it's not warm enough. Maybe a freak ice storm, or you didn't plan ahead; whatever, you're out and you're cold.

In this situation, you do whatever you can to stay warm. I recently had a situation like this. I had two tarps with me, and no tent, so it was slightly different. I had one tarp on the ground, a small fire next to it, and the other tarp over top with one edge going over top of the fire. That is, I had an indoor fire in order to provide enough warmth. You could modify this for a tent though, especially in an emergency situation where you're willing to cut holes in your tent to accommodate a fire in the floor and an exhaust hole in the roof.

In fact, I can tell you that if I felt my life depended on it and I was using a tent, I definitely would rip a hole in the bottom of the tent to put it around a fire. It would be similar to the experience that I did have, mentioned above, except in a tent. I would be warming my tent based on objective reasoning.

If you are concerned about the safety hazard of an indoor fire, as you should be, or if you don't want to risk ruining your tent, you can keep the fire outside and use other things to warm the inside. Possibly other dangerous heating tools (ex: camping propane stove, gel burner, etc.) inside, or better yet just heat other objects, such as rocks, and bring them in (carefully! don't ruin your bag or tent).

Or use something to redirect heat from an outdoor fire into your tent: some kind of reflector, or a tarp to redirect warm air flow, or whatever you have. All of these methods are either too dangerous or unwieldy to use for warming your sleeping bag, so it needs to be the tent itself that is warmed.

If you have hand/foot/body warmers, like the chemical ones for example, then you should just use them in your bags at this point so you don't have to heat the whole tent.

Caveat on the emergency

If you are in this emergency situation, it might be easier, safer, and keep you warmer if you just go outside your tent and huddle close to your heat source. You can adjust your body's distance from the fire to keep yourself warmer than you would be inside the slightly warmed tent, so at that point abandoning the tent might be wiser than heating the tent.

Similarly, I have spent time curled up around tiny fires for warmth. Also, I keep one of those little emergency ponchos in my emergency gear, and I have used them to trap the heat from a fire: I started a tiny fire, put the poncho on, kneeled down by the fire and positioned the poncho so that it covered the fire and trapped warmth inside the poncho with my body and made me a lot warmer. In fact, the poncho example is specifically a case where I abandoned the cold tarp-tent to get warmer, and once my wife realized how much better I was doing she came out to join me too, so it is right up your alley as a counter-example.

However, when it gets cold enough, you can actually be hot on the side of you facing a fire and cold on the other side of you. In this situation, you could be better off with the tent ripped open at the bottom and put around the fire.

Summary

Basically, when heating a tent artificially makes objective sense literally comes down to "Because I want to" (ie: point #1), and "Because I need to" (ie: point #3 and maybe #2).

If you want to, you are willing to sacrifice something else for the luxury; that's what gear choice all comes down to, balancing by sacrificing in one area to gain in another.

If you need to, you don't have much choice. It's way freaking super cold, or for whatever other reason your gear is not sufficient.

Answer 6

After reading the "you're doing it wrong if you need to" I'll take a contrarian view:

I've camped several times using an outfitter's tent -- canvas walled, barely liftable dry, and barely dragable wet.

These are often equipped with an non-flammable thimble for use with a wood burning stove.

What conditions have I used these:

• Hunting. If you have been tramping through wet scrub birch all day peering through the fog for your mountain sheep, being able to come back to a spot that is warm and dry makes for a pleasant end to the day.

• Based camp exploratories in winter with junior high aged kids. While we usually slept by the fire, we had one such tent rigged up with lines inside. This made it easy for the kids to have dry mittens, socks and footwear the next day.

I've done major dogsled (2 week) in winter. And we were glad to get an occasional night in a trapper's cabin. This isn't strictly speaking a tent, but the idea is the same. This allowed us to get sleeping bags completely dry. If you read accounts of arctic exploration the frost content of the bags builds continuously through the trip.

The reasons not to are good ones too. Carrying a stove + fuel, and ensuring that you didn't smother yourself in CO2 or poison yourself with CO is difficult, and usually wouldn't warrant the payload.

Being able to do it with a wood fired appliance to me makes all kinds of sense in wet or cold weather if the area allows that degree of wood use.

Answer 7

In my humble opinion, there is no condition where heating a tent makes objective sense. The impracticality of heat generation usually means that travelers who would benefit or need heating the most (circumpolar travelers) are the ones who will most probably skip it. In that sense, the decision for all cold weather travelers becomes entirely subjective as it will be a matter of choice, not of necessity (I'm pretty much echoing Aaron's conclusion here).

The only true burden to heating a tent over a long period is fuel considerations. Of course, if you're carrying a wood stove, you can resupply in the wild and don't necessarily need to carry the fuel with you so I'll ignore that resource. Anyway, as soon as you reach about 55-65° north depending on the area being continental or rainy oceanic climate, you'll begin having a harder time finding trees. We're left with two choices: Carrying fossil-fuels (non-renewable during the trip) or batteries and solar power (which are far from the best in the extreme cold). Both are a heavy additional load. The usual choice will be to do without and just carry better sleeping gear. Cost-benefit will far surpass heating the tent.

As for high-altitude climbing, it's just not going to happen. The steeper the slope, the more gravity works against you. Pulling a sled uphill is the worst thing I've ever done. I'd never consider it again. Minimizing weight then becomes one of the most important criteria.

So to summarize, the colder it gets, the less you can rely on an easy fuel source. The longer you travel, the worse carrying fuel becomes. So the only reasonable condition in which heating a tent becomes practical is if you're traveling in a lower latitude forested region and don't need to carry your fuel.

Answer 8

Never in place of sleeping bags and pads, or even extra dry clothes, but maybe as a backup.

If it’s a weather situation where you need the heat to avoid hypothermia, reliability might be your critical determinant. So one answer to “the conditions under which an artificial device to heat a tent makes objective sense” might be “when the reliability of your heater exceeds the reliability of your other methods” a circumstance which wouldn’t usually happen at the outset but might somehow develop in the field.

Insulating layers plus body heat are a pretty reliable system: The insulation has no moving parts, no fuel, few opportunities to break catastrophicallly etc. And under normal conditions the body generates heat. But I can imagine a situation in which:

1)the bulky lightweight insulators get soaked with water, catch fire, or are simply lost to wind/current/animals etc. while some of your heavier more compact gear is not.
And/or 2) the human is already so severely hypothermic they are not generating heat. In that situation the true redundancy provided by a totally independent warming system which functions by completely independent principles might be valuable.

So my sense is you would never choose a heater over a sleeping bag/clothes/good tent as your “Plan A” but you might choose a heater as a backup system (especially if you can for all intents and purposes build it out of field-proven things you have with you like stove-heated hot water bottles).

Answer 9

In an emergency, I have used a flameless oven, with the hot steam venting out of the tent using a tube. These reactions produce a ludicrous amount of steam, so you need to vent the steam. I rigged a Camelback water sipper silicone tube to vent the steam.

These are usually salt and a magnesium compound that react with water to create an exothermic reaction and boil the water.

It is possible to keep topping off the bag with water and use several pouches of materials, it takes about 15 minutes to use up one consumable pouch from the kit. Then, pour the salty hot water into Nalgenes or otherwise to create instant hot water bottles as needed.