Is a heat exchanger pot worth the weight?

[John RB]

Roger, i couldn’t find that pot on ebay. Is there a way to share (within forum rules) the seller or at least keywords that would help me find it?

[Jon Fong / Flat Cat Gear]

Wow! why would almost every response be flagged with

This reply has been reported for inappropriate content.

[Roger Caffin]

why would almost every response be flagged with
Because some miserable ratbag using the name geppotronico managed to hack into the system and splat around in the database. He has been removed, but his actions have yet to be dealt with.
I have unreported all the postings in this thread, but it took a while.

Sigh

[Roger Caffin]

that pot on ebay
Dan bought them, not me. I suspect they may have been a ‘disposal’ sale as they were quite cheap. This one may be more or less the same:
https://www.ebay.com/itm/Heat-Exchanger-Pot-1L-Foldable-Cooking-Pots-Mesh-Bag-Outdoor-Camping-Cookware/303670195818?hash=item46b427766a:g:xvAAAOSwPcpfTHD8

A search for ‘heat exchanger pot’ on ebay will bring up lots of them, often ‘Fire Maple’, and mostly dearer.

There are also a couple under ‘hard anodised pot’, but watch out for the cost of shipping from a USA vendor.

Cheers

[John RB]

Thank you Roger.

In your opinion, would this it well with a Soto Windmaster?

[Chris FormyDuval]

Give me some criteria and I’ll run a test for you this week. It’s also available with Olicamp branding https://www.ebay.com/itm/NEW-Olicamp-XTS-1L-Hard-Anodized-Aluminum-Pot-Heat-Transfer-System-Backpacking/362397617268?epid=1557506730&hash=item546094cc74:g:F0kAAOSwQZdgIGq2

[Roger Caffin]

The only problem with putting HX pot A on stove B is whether the pot supports mesh with the cover ring on the underside of the pot. You do NOT want the risk of the pot supports getting tangled up with the ring when you lift the pot up. Flames and hot metal going in unexpected directions.

Cheers

[Chris FormyDuval]

Here are a couple shots with the windmaster. 

[Chris FormyDuval]

[John RB]

Oooh nice, that looks its great – with the 4 prong one, if my eyes don’t deceive me.

Chris have you found the combination with the windmaster to be a good one in wind/heat exchange, given the rep the windmaster has with “regular” pots?

[Chris FormyDuval]

Haven’t actually used that combination yet. I can try with a little fan and let you know.

[Jon Fong / Flat Cat Gear]

Well, here is some test data to help answer that question.  Bottom line, in windy conditions making more than 7 boils a Heat Exchange is a good idea.  For most weekend trips a traditional pot is just fine.

 

 

[Bill Budney]

Jon:

• You have boiled more water than most other people.
• You have demonstrated that all pots/stoves need a windscreen in any significant amount of wind. Wind is commonly above 8 mph.
• You make great windscreens.
• A tall windscreen (just a cylinder up the sides of the pot) transfers heat more efficiently (per gram of added weight) than an HX pot.
• Adding a partial lid to the windscreen (not to the pot) increases heat retention and reduces convective losses in the system, which further increases efficiency.
• You have made windscreens like that — I’ve seen pictures.

Why not just make taller windscreens? Do they have some limitation that isn’t immediately obvious?

Known limitations:

• The entire pot will be hot (including handles), so you will want to use a pot lifter.
• A tall windscreen may not fit inside the pot for storage and travel. Maybe roll it (loosely) around a long spoon handle or stake bag?

[Jon Fong / Flat Cat Gear]

OK, so here are the limitations: I released a tall Ocelot windscreen a while ago.  I noted that for best fuel efficiency, run the stove at a lower power level.  Shortly thereafter, a customer sent me a video of the windscreen is operation, and the upper half of the windscreen was glowing bright read.  Apparently, he thought that running at a burn rate higher than low would be fine.  A second customer sent a photo of the same thing.  At that point, I really internalized that 1) customers do not read instructions and 2) this was a liability problem.  So, going forward, all Ocelot windscreens are short to prevent overheating the windscreen surface.  Yes, I understand that the hot gases are flowing up that way anyway and can burn you.  But the optic of one of our windscreens glowing bright red is unacceptable.  My 2 cents.

[James Marco]

Actually a heat exchanger does the same as containing all heat with a windscreen and ventilated lid. In some cases it will do better. Heat exchangers are intended to be used with a good windscreen, anyway. But on low heat, there is no noticeable difference. (Unless you are in the wind. ) Even in wind, they can perform as well. I simply added a series of radial ridges to the bottom of a grease pot. Add a wind screen, and, there is no difference. KCal absorbed by the water (food) is the bottom line. And a grease pot with a wind screen is still the “lightest for the mostest”.

[Bill Budney]

> the optic of one of our windscreens glowing bright red is unacceptable.

OK, that explains it.

(OTOH, it almost proves that a windscreen is more efficient than an HX pot!)

[Jon Fong / Flat Cat Gear]

I am keen watching the new MSR Switch; the pot with the hemispherical bottom.  The advantage is that a hemisphere doubles the surface area of the bottom of the pot; though that may not translate to efficiency.  IMO, the  future may be to use a pot shape like this with a windsheild integrated into the mug in one package.  Fins are great for fast speed and help with blocking the wind.  They are also limited in how you cook with them.  Since I do not care about speed and I am more interested in cooking, the hemisphere bottom looks great.  Now they need to inovate a good windscreen and bring the weight and price point way down.  I would be happy with a system that could boil 500 ml using less than 7 g in calm condition but also less than 10 g in the wind.  That and have a system weight (including lid & stove) less than 150 g.   My 2 cents.

[Bill Budney]

It’s worth a try. It isn’t immediately obvious how the curved bottom is better than a regular HX, but if it does heat more evenly and/or saves weight (doesn’t look like it does), then that would be great.

Or use aluminum pots/pans and a windscreen. ;)

[Jon Fong / Flat Cat Gear]

From pure geometry, a hemisphere has twice the surface area of a circle.  That does not mean that the heat transfer will be double but, it should be better.  My 2 cents.

 

[Bill Budney]

Sure, but a heat exchanger adds something like 30%-50% more surface area to the circle. The Switch pot doesn’t add a full hemisphere. Does the partial sphere add more or less surface area than the HX?

It appears, from photos, to be close. We need measurements.

(The sides of the pot add several hundred percent of the area of the circle, but I understand why you don’t want to use that approach. At least not for customers.)

[Jon Fong / Flat Cat Gear]

The calculation are for a Hemishpere and not a Sphere: That is where the 1/2 came in the formula above.  An HX pot will probably be more efficient with material  as it is in the plane of the flame spread than the hemisphere as you don’t know how well the flames will hug the surface. My 2 cents.

[Bill Budney]

Yes, the Switch pot looks like less than a hemisphere to me. But I haven’t seen one close up.

Yes, that’s my estimate, too, that the HX might be more efficient at heat transfer, but the Switch could be lighter. We need measurements! :)

[Roger Caffin]

To quote Cascade Designs (MSR) on the Switch:
Lightweight:
Complete system weighs 13.8 oz (392 g); stove weighs just 4.1 oz (117 g).
US$140, but out of stock

“Lightweight” Yeah, right.
My 1.5 L Ti pot weighs 115 g.
My V7 remote inverted canister stove weighs 49 g.

Cheers

[Bill Budney]

Oh, sure, the Switch product is not very interesting. The question is whether the hemispherical shape has any advantage over an HX pot?

We have already established that a proper windscreen is more efficient than an HX pot, but the most efficient windscreen is a potential liability hazard, no matter what instructions are included.

That explains why nobody sells the most efficient shape. You can get close with a tall titanium (or aluminum) foil windscreen and an aluminum foil lid, but you have to make it yourself.

I think that you get pretty close with your photos of your MYOG aluminum foil windscreen.

[Roger Caffin]

no matter what instructions are included
That is the sad part (for the mfr).

Cheers

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