Wednesday 5 June 2024

Update from the Cape Wrath Trail: The Heat Exchanger Pot Performed Even Better Than Expected

On the Cape Wrath Trail.

Since writing the piece below on heat exchanger (HX) pots I've spent 19 days on the Cape Wrath Trail (story to come) using the Jetboil Stash HX Pot and the Soto Windmaster 4Flex stove with a 230g Primus Power Gas canister. The results were surprising, not to say astounding. The canister lasted for 15 days. I expected 12 days at most and would have been happy with 10. The most I've ever had from a canister with a non-HX pot was 11 days and that was in warmer, drier, and much less windy conditions than on the Cape Wrath Trail. The regulated burner was also impressive as the falloff in power was barely noticeable with the stove boiling water fast right up to the point when the canister was empty. I was boiling 1.3 to 1.5 litres of water a day and occasionally simmering food for 5 to 10 minutes. 

Tony Hobbs at our third camp together.

Tony Hobbs joined me for four camps and used the MSR Pocket Rocket Deluxe stove with the Fire Maple Petrel Heat Exchanger pot I describe below (he didn't find he had to do much to get the stove pot supports to fit into the slots on the base of the Petrel, just not open them fully). We did one crude comparison boil with 300ml of water and Tony's setup took a whole 19 seconds longer. With no scales we weren't able to compare how much gas was used. I'll be testing this soon. I don't expect any difference to be significant. Tony did notice that if he had the stove on full flames did come out of the heat exchanger and lick up the sides of the pot, wasting heat, so he usually turned the stove down a little. This happens because the Petrel pot is quite a bit narrower than the Stash pot.

Here's the original piece on HX pots.

Jetboil Stash pot and stove

Heat exchangers are corrugated fins or vanes on the base of a pot that capture heat that would otherwise be lost to the air and up the sides of the pot and transfer it to the contents. Jetboil launched the first stove system with a heat exchanger (HX) pot twenty years ago. Since then I’ve used and reviewed several such systems, from MSR and Primus as well as Jetboil. I’ve always liked the fast boil times and fuel efficiency yet I never thought of taking one on a long-distance walk due to the weight and bulk (the lightest, the Jetboil MicroMo, weighs 349g). Until that is Jetboil launched the Stash, a basic burner and HX pot that at 200 grams could genuinely be called lightweight, back in 2020. I reviewed it for The Great Outdoors in 2021 and said I’d consider taking it on my next long walk. I’ve used it a great deal since then and I think it’s a wonderful unit for solo backpacking. I’m taking the Stash pot on the Cape Wrath Trail soon but maybe not the Stash stove, for reasons outlined below.

Jetboil Stash

It’s the pot that’s impressive with the Stash. It’s made from hard-anodised aluminium and holds 800ml. It’s not tall and narrow like many HX pots and so easier to stir and to eat from. It weighs just 140 grams. The Stash burner is also light at 60 grams but doesn’t have the performance of higher spec stoves as it’s not regulated and so power declines in the cold and as the canister empties. It also has no wind resistance at all so a windshield is needed in all but the gentlest breeze. It is still a perfectly adequate stove that I’ve used on many trips but there are better ones.

MSR Pocket Rocket Deluxe with Jetboil Stash pot

After a year with the Stash, using it on every trip, I decided to try the pot with other stoves in cold and windy weather. The results were impressive. With the regulated MSR Pocket Rocket Deluxe (PRD) stove water boiled faster than with the Stash burner, the power stayed high with an almost empty canister, and it didn’t need a windshield until the wind got quite strong. The Optimus Vega remote canister stove and Stash pot again outperformed the Stash stove. This setup also has the advantage of being low profile and more stable. However there is a significant weight penalty – it’s a 100g more than the PRD and 125g more than the Stash burner. With the Vega the canister can be turned upside down to turn it into a liquid feed stove in extreme cold though this does increase fuel usage. I only use it in winter.

Optimus Vega stove with Jetboil Stash pot

The Stash pot is superb, the best solo backpacking pot I’ve used. You can’t buy it on its own though, only with the Stash burner, and Jetboil warns that it should not be used with other stoves. When I asked why Jetboil said “the Stash pot was designed for high performance on the Stash burner as a Cook System. However, we cannot guarantee its performance or safety on all the assortment of burners and pan supports available, so we recommend only to use on Stash”. So if you use it with other stoves it’s at your own risk.

There is a big disadvantage in doing so anyway. The high cost - £155 at the time of writing. That makes for an awfully expensive pot! So what are the alternatives and are they any good?

Fire Maple HX Pots

The only standalone HX pots I knew about until recently were ones from Vango and Optimus that are too heavy for solo backpacking except on short trips, at least for me. The Vango Ultralight Heat Exchanger Cook Kit, which I have had for a few years, comes with two bowls and cutlery and has a cosy round the pot. The total weight is 387g, the pot alone 286g*. The Optimus Terra Express HE weighs 377g and has a non-stick coating. Both are worth considering for duos.

Soto Windmaster 4Flex stove with Fire Maple FMC-XK6 pot

Searching online for lighter standalone HX pots brought up some fascinating videos from Flat Cat Gear about the ultralight 800ml Fire Maple Petrel HX pot and an interesting article called  Superstove for Optimal Backcountry Cooking by Alan Dixon and Jaeger Shaw on the Adventure Alan website that recommends the 1 litre Olicamp XTS pot (which is identical to the Fire Maple FMC-XK6 HX) as the best alternative to the Stash pot and also mentions the Fire Maple Petrel HX pot. Curious to try them I bought both Fire Maple pots, at a combined cost less than a third that of the Stash.

Soto Windmaster Triflex fitted onto Fire Maple Petrel pot

Both the pots are hard-anodised aluminium with plastic lids – an excellent one on the Petrel, a poor one on the clumsily named FMC-XK6 (which I’ll call the FMC from now on). The Petrel is tall and narrow and not so good for simmering food or eating from as the wider and bigger FMC. The Petrel weighs 166g, the FMC 195g. The Petrel is unique in having slots on the base of the heat exchanger. These are designed to fit the pot supports of a Fire Maple stove but also just right for the Soto Windmaster with the Triflex three-pronged supports (the stove comes with a four-pronged support, the Triflex is an extra option). The Windmaster is a powerful regulated stove comparable with the MSR Pocket Rocket Deluxe (which won’t fit in the Petrel slots unless you do some modifications as shown in this Flat Cat Gear video). The only other stove I have that fits the Petrel is the Jetboil Mighty Mo, which in fact fits even more securely than the Windmaster but is a fair bit heavier – 98 rather than 68 grams. Of course you can just balance the Petrel on a stove without using the slots but that means it’s less effective, Having the burner inside the heat exchanger improves fuel efficiency, boiling time, wind resistance and stability.

Of the two pots I prefer the FMC as the width makes it easier to use than the Petrel. The FMC is 55g heavier and a bit bigger than the Stash pot. The combined weight with the PRD stove is 279g. The Petrel is 25g heavier than the Stash. With the PRD the total weight is 234g. Either of these is a good alternative to the PRD/Stash pot combination, which weighs 225g, or the Windmaster 4 Flex/Stash combination, which weighs 229g (the Triflex supports are too short to be stable with the Stash pot).

The Stash pot plus the PRD or Windmaster stove combines the best pot with the best canister top stoves that I’ve used. But for the price of the Stash you could buy six Fire Maple pots.

Why HX Pots?

Do HX pots really have advantages? That depends! Faster boil times are often touted as the big plus but I don’t think a few minutes difference really matters, and fuel efficiency is higher is if a stove isn’t run at full power. What is significant is reduced fuel usage, especially on long trips where there may be many days between resupply points. Heat exchanger pots also increase performance in cold and wind, which I also think more important than fast boil times.

From left: Jetboil Stash, Fire Maple Petrel, Fire Maple FMC-XK6, Jetboil MicroMo

HX pots are all hard anodised aluminium which may not last as long as titanium but which costs far less. Why not titanium? Jetboil did try this with the Sol Ti stove but there were problems with the heat exchanger fins melting and it was discontinued. No-one has made a titanium HX pot since as far as I know so I guess there are possibly insurmountable technical problems.

Three years ago I posted a piece on pots in which I said of HX pots “these do reduce the amount of fuel needed and speed boiling times but also add weight. I like a heat exchanger pot in winter for snow melting but otherwise I find a standard pot fine”.  I’ve changed my mind. I now use an HX pot year round.

Heat exchangers. Clockwise from top left: Fire Maple FMC, Fire Maple Petrel, Jetboil MicroMo, Jetboil Stash

I can see no big disadvantages to HX pots. The size and weight increase over titanium pots isn’t that big. The Evernew 900ml titanium pot that I’ve used on every long distance walk for over twenty years weighs 137 grams, just 3 grams less than the Stash pot! The 900ml MSR Titan titanium pot is lighter at 125 grams but there’s still only a 16g difference. In comparative tests I found that on average using HX pots meant a fuel saving of about 4 grams per 500ml of water boiled. So the weight difference between the Titan and Stash pots covers enough fuel to boil 2 litres of water.

There is a view that HX pots are unsuitable for anything other than boiling water but I’ve found this is more dependent on the burner than the pot. This opinion may have come about because the first HX stove systems didn’t simmer well. This isn’t true of most current ones and certainly not of HX pots combined with regulated stoves. Having a stove and pot that aren’t locked together also helps as you can easily lift the pot off the stove to see the flame when you turn it down. I’ve simmered food without problems in HX pots with PRD, Windmaster, Stash, Vega, and other gas stoves.  

Testing, testing

Testing lab

I recently reviewed a selection of stoves for The Great Outdoors in which I compared boil times and fuel usage with HX and non-HX pots. The results further convinced me that HX pots are worth using. I then did a follow-up test comparing the Soto Windmaster Triflex with the Petrel pot, the Stash stove and pot, and the Jetboil MicroMo. The Soto had the fastest boil time, the Stash took 17 seconds longer to boil the water but used a gram less fuel. The MicroMo was between the two on both counts. Practically there’s no significant difference. However this was in warm calm weather with full canisters. The Stash stove doesn’t perform as well as the others when it’s windy or in the cold, especially with a less than half-full canister. As well as being regulated the Windmaster, like the PRD, has a small windshield round the burner, and is further protected by the Petrel heat exchanger.


Windshield round MSR Pocket Rocket 2 stove and Evernew titanium pot

A big problem with the Stash and similar stoves is that they aren’t wind-resistant. Anything above a gentle breeze can blow the flame sideways and reduce the performance significantly, sometimes preventing water boiling. A few stoves like the PRD and the Windmaster have tiny windshields round the burner that do make a difference though in strong winds the performance still deteriorates. The Jetboil system stoves like the MiniMo and MicroMo are much the same. The only stoves I’ve used that don’t require any wind protection are the MSR Windburner and the MSR Reactor stoves. These are great for winter use, especially snow melting, but weigh 425 and 432g respectively. With other stoves I use a foil windshield that can surround three sides of the burner and which comes part way up the side of the pot. It woirks well. I’ve never had a canister get hot doing this. My current foil windshield weighs 55g.

MSR Reactor. Great in the snow but heavy

There are windshields available that fit around the burner. I tried a few of these in the past and found them clunky, awkward and not as efficient as the foil windshield. However Flat Cat Gear has a range of windshields for different stoves that look effective and easier to use.

*All pot weights include the supplied lid. This could be replaced with a lighter one, such as a piece of foil. A lid increases fuel efficiency so I always use one.

1 comment:

  1. hope you had a fantastic experience on the CWT. Note sure what your mate Tony was thinking with a tarp - risking santiy and health in peak midge & tick season