MYOG: SUL Remote Inverted Canister Winter Stove V8

First of all, another excellent article about the design and thought process going into developing a stove. Congrats. I was impressed with the V7 design and your ability to get the weight down to 45 g (not including legs). So, the V8 is about 15 g lighter than your previous versions? How does the fuel efficiency compare (V6, V7 & V8)?

I may have missed it, but what is the advantage of the shut over a pre-heat tube? I tend to like the pre-heat tube as in fair weather, you can use it in the upright position.

Finally, what are your thoughts on the Fire Maple Petrel Summit? It looks like a solid replacement for the Kovea Spider. I just bought the Petrel Summit but have yet to have time to test it out.

Hi Jon

I was impressed with the V7 design and your ability to get the weight down to 45 g (not including legs).
Correction: that 45 g is with a short CF handle and does include the legs. 45 g complete.

Fuel efficiency in still air is about the same for most small stoves. Ignore all marketing claims. Pot size is usually more important. But of course if you run a small stove in the wind, it will cost you. I do not understand why anyone would not use a windshield. My Ti foil one for the V7 weighs 7 g.
Yes, there are bound to be some exceptions with worse efficiency.

Why a heat shunt instead of a heat exchanger tube over the top? Two main reasons.
The first is the weight saving: a small strip of aluminium heat shunt vs a long length of heat-resistant alloy metal.
The second, and far more important one, is manufacturing difficulty. That heat exchanger tube MUST be hermetically joined to the stove body, and that usually requires some sort of welding. Welding an alloy tube to an aluminium body is not easy. Yes, you could alternately use some sort of metal coupling, but that adds more weight and may not be all that reliable in the long term, given the differences in thermal expansion. So most companies use brass, which is much heavier.

I should add that you can always use one of my remote inverted canister stoves with the canister upright. But in cold weather you can run out of propane that way.

The FM Petrel Summit should be a reliable stove (imho), but for me it has two drawbacks.
The first is the weight: 111 g vs 45 g. OK, compared to the weight of a pack, the difference is not great.
The second drawback is the valving. The PS has only one valve, at the canister, controlling liquid flow. Controlling liquid flow to your required setting is far more difficult at the best of times, and always has a long time delay before any change happens. So for me, the fact that there is only one valve and no fast emergency shut-off, is a real deficiency.

Eh, well, I am of course biased!

Cheers

45 g for a stove is amazing.  Although, like you said, the weight savings isn’t noticeable but combined with other weight savings it is.

why would you run out of butane in cold weather if you ran it upright?

I should add that you can always use one of my remote inverted canister stoves with the canister upright. But in cold weather you can run out of propane that way.

OK, I am confused now.  I thought that the latent heat of vaporization was needed to manage the temperature of the stove body.

Starting to see more and more off-brand stoves use heat shunts instead of tubes. I think it’s a really smart decision. If you think about it, it’s really just a clever rethinking of a well and long established principle in stoves. The burner bell on classic stove designs, the heat accumulator “star” in the base of newer designs from Primus and Optimus (Optifuel, Omnilite), they all do one thing: transit heat into the evap zone.

I think it’s superior in many ways. As Roger points out, I don’t think there’s an example of a preheater tube stove with a regulator at the stove. So fine adjustments are possible and it elimates the issue of tube fowling and is easier to manufacture. I think shunts/accumulators are both the future and the past of stove designs.

Roger, yet another banger of a post, one of my favorite series on this site! I just wish somebody would really rethink these ideas with liquid fuel stoves. Aside from the Soto Muka and Stormbreaker (wonderful stoves that are wonderfully complicated and intricate), LF stoves have not been advancing in years. Somebody should. It may be me some day. I have a few ideas.

The waste and weight of cannisters really bothers me.

Hi Jerry

why would you run out of butane in cold weather if you ran it upright?
It’s propane that runs out when the canister is upright, not butane.
Butane boils at ~0 C, but propane boils at ~-42C: physics.
So at -10 C, the propane is boiling off well, but the butane is sitting there doing almost nothing. You end up with a canister 2/3 full of liquid butane but nothing coming out. Well-known problem, and the whole rational for a remote inverted canister stove.

Cheers

Watching the evolution over the years has been inspiring. Keep up the amazing work.

Thank you.
Cheers

My V4 is still working perfectly…I’m really glad to see you continuing to innovate!  Thanks for yet another great read.  Looking forward to V9 and the blog that comes with it.

V9 ?@?@?#!#!%!%? ??
I may be running out of ideas!

But thanks for the info re V4.

Cheers