Its winter here in Australia and that means sub zero conditions in the Southern Highlands and Snowy Mountains. Cold is the enemy of my Jetboil because as low temperature makes it more difficult for the gas in the canister to evaporate and the pressure is reduced.
So off to the internet to look for solutions. I was initially looking to see if there was an adaptor available to make the canister ‘remote’ in the way my old epigas alpine stove used to be. Instead I sumbled across a much cheaper DIY option that is genius in its simplicity – the Heat Exchange or HX Strip
This info comes from the Backpackinglight forums and the thread I got this info from can be found HERE
The concept is super simple. A copper strip is strapped to the side of the canister so that one end is in the flame. It conducts heat from the flame to the canister.
On the BPL forums it seems to have gained the name the Moulder Strip after the chap who brought it to everyones attention and optimised it. Its also been known as the Alpine Bomb.
The picture above is the best itteration I’ve seen and the one I’m looking to copy. The things to note are:
- The shape of the strip is super simple (easy to both make and pack!)
- This will work on any upright canister stove I can think of
- Its very lightweight, infact an upright canister stove with HX strip will be a lot lighter than a stove with remote canister
- The HX strip is tightly clamped and shaped to the canister with a good contact patch. This is key for optimal heat transfer
- The velcro strap is protected by a bit of heat resistant silicon to prevent it melting
- The system can be easily added or removed from the canister to allow changing and use in variable conditions. (This should only be used in cold conditions)
Copper is the best material to work with for this. Its a very good thermal conductor, it has a high enough melting point and its maleable enough to be easy to work with.
Aluminium can work but needs to be twice as thick because of its reduced thermal conductivity. It is available from Bunnings though, copper is not 😦
What do you think, let me know in the comments
What is the safety risk Ian? I am with you in that I would love a way to keep the canister “warm”. I guess I am erring on the side of caution, I think the cosy idea is a better option, probably still not as effective as the strip. Our Scout group is using some different “remote” canister stoves, but as we know, with that comes the payoff of extra weight etc. Whilst I know it isn’t a new idea, I guess that is hasn’t become mainstream for the very reason that the canisters are really supposed to be heated above 50c, hence why you shouldn’t even use a windshield around them.
For a lot of detail on the temperatures actually transmitted to the canisters have a read of the BPL forum topic linked in the blog post, it’s discussed and measured quite a bit.
It seems the canister itself acts as a heat sink absorbing and dissipating enough energy as long as the air temperature is cold enough. This is a technique specific for cold (as in freezing) weather.
This is correct, Ian. I tested it very thoroughly with ambient temperatures far warmer than one would ever use the copper strip and it still did not overheat. I’ve used it a lot in the field for the past several years with absolutely no issues.
Fantastic Bob, thanks for replying and really appreciate you sharing what you have tested and found
Thanks, Mate! I hope you had a chance to use it last winter in Oz. Very honored that it might help an outdoorsman Down Under.
Thanks, Mate! I hope you had a chance to use it last winter in Oz! Very honored that this is useful for an outdoorsman Down Under.
I have similar interests and will definitely be checking out your website in the future.
Winter is approaching here in NZ and I’m revisiting this as I make sure my gear is optimised. The original aluminium Moulder Strip I made is in a storage unit in Australia somewhere but I’ve got a piece of copper pipe in my hand now that I can use.
On a quick safety note as with any stove this isn’t something that should be left roaring away but its easy to monitor.
The gas canister standard specifies they need to be safe to heated up to 50degC. ‘Ouch’ temperature is somewhere just above 40degC so a simple touch test on the canister will reveal if a problem is occurring. Based on information linked above and commented by Bob after testing problems have not been occurring.
This is very much a method for use when temperatures are down close to freezing or below as these are when the gas needs warming a bit to burn effectively. At temperatures above freezing its not required
Just a further bit of research on this link here http://bushwalkingnsw.org.au/clubsites/FAQ/FAQ_Mixtures.htm
Because gas canisters get colder as you use them (sometimes frost on outside) in lower temps it might only be the propane burning. I think my rule of thumb will be to use the Moulder Strip anytime its down close to freezing, say 5 degC and below or when there is a frost. If nothing else it will mean I get ‘best value’ out of gas canisters.
I keep an eye on my stoves anyway, I don’t tend to cook for long on them either. I think the mention of ‘roaring’ in the linked article is a good one. If the pressure is increasing to the point of causing the stove note to change it would be an indicator that there is a problem.