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Heat Exchange Stove Shootout: Part 3
Heat Exchanger Stoves
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Franco Darioli
(Franco) - M

Locale: Melbourne
Heat Exchange Stove Shootout: Part 3 on 09/17/2009 22:37:36 MDT Print View

Here
http://www.acecamp.de/en/Kitchen/
scroll down to art 4708, listed at 160g
Franco

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Heat Exchange Stove Shootout: Part 3 on 09/17/2009 23:51:18 MDT Print View

Hi Franco

Hum, yes. Thanks.
I think I can identify the Chinese factory that came out of ... :-)

Cheers

Tomas Reinhardt
(tomky) - MLife

Locale: Tatry
Heat Exchange Stove Shootout: Part 3 on 09/18/2009 02:05:55 MDT Print View

Acecamp 4708 153g (weighted), my 113g mod: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=23089

Edelrid Opilio 170g
Catalog Sports10-GB(8.28 MB) page 81:
http://www.edelrid.de/index.php?option=com_facileforms&Itemid=629
see also Stormy Evo with Heat Exchanger, Hexon multifuel 220g
Video(German):
http://www.odoo.tv/OutDoor-2009-Kueche-Special.548.0.html

M G
(drown) - F - MLife

Locale: Shenandoah
Re: Re: Rotating windpro, and Primus Express Spider on 09/18/2009 17:46:07 MDT Print View

Hi Roger,

Thanks for the comments and the suggestion of the Spider, that and the other stoves posted by our European friends look lovely but unfortunately I am leaving in 4 days for a Sierra trip and need a cold weather stove now. This leaves me with a windpro and a bottle of loctite.

I completely unscrewed the connection and applied the loctite to the tube male part and rescrewed the adapter to the tube in the upside down position I needed. Once dry I tested it and it appears to be completely leak free...for now.

Thanks for the advice.

Hikin' Jim
(hikin_jim) - MLife

Locale: Orange County, CA, USA
Re: Re: Heat Exchanger Stoves" on 09/18/2009 21:22:42 MDT Print View

Tony Beasley wrote > ...for winter my favorite is modified Coleman Extreme stove under a JetBoil GCS pot and I challenge any other stove pot system to melt snow as fast and efficient at 0F.
Now that is a fascinating idea. I'll have to try that. I assume you use a windscreen also? Any tricks to help avoid melting the neoprene?

HJ

Edited by hikin_jim on 09/18/2009 21:41:37 MDT.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Heat Exchanger Stoves" on 09/18/2009 23:38:44 MDT Print View

Hi Jim

Tony will need to reply about using a windscreen, but I will bet you he did!

The neoprene - I worried that it would burn when I was testing several stoves with neoprene cozies. Somewhat to my surprise, I found that*provided the cozy was pushed right up to the rim* (so it didn't protrude at the bottom), there was no problem. The fins really suck the heat out of the flames. I found I could hold my hand in the exhaust stream beside the pot without any real problem. Try that with a bare pot! (DON'T!)

Cheers

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: Re: Re: Heat Exchanger Stoves" on 09/19/2009 00:46:25 MDT Print View

Hi Jim,

I always take a windscreen with me, for the Xtreme I use and old and very crumpled, cut down MSR Whisperlite windscreen but last time I used my Xtreme/JB GCS pot in 0F conditions it was in a hut without a windscreen (pic below). The only damage that the neoprene cozy has suffered is from rodents eating it in the same hut, the little plastic covering on the feet of my Xtreme stove was also attacked and I lost my candle and my mate had his cup stolen.

Tony

<center>
Xtreme stove and JB pot


</center>

Edited by tbeasley on 09/19/2009 00:47:50 MDT.

Hikin' Jim
(hikin_jim) - MLife

Locale: Orange County, CA, USA
Re: Re: Re: Re: Heat Exchanger Stoves" on 09/20/2009 18:18:12 MDT Print View

Roger, Tony,

Thanks, that's good information. The neoprene on JB's seemed at first to me to be a foolish thing (why put something that can melt on a pot for goodness sake?), but it's wisdom has become apparent over time.

HJ

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Re: Re: Heat Exchanger Stoves" on 09/20/2009 22:27:41 MDT Print View

Hi Jim

You didn't ask about wisdom.

My tests show the neoprene cosy has virtually no effect on the heating rate. But a lid has an enormous effect.

Cheers

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: Re: Re: Re: Re: Re: Heat Exchanger Stoves" on 09/21/2009 15:52:46 MDT Print View

Hi Roger

>My tests show the neoprene cosy has virtually no effect on the heating rate.

At warmer ambient temperatures this may be correct, at very cold temps I am not sure, we need to test the neoprene cosy at -20C.

>But a lid has an enormous effect.

I long time ago I did some tests boiling water with and without lids and at warmer ambient temps the lid made very little difference but at cooler temps it did.

If we can work out how to do affordable controlled cold temperature tests a series of tests on the above would be good.

Tony

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: Poor Windpro performance? on 09/21/2009 16:06:52 MDT Print View

I went through about the same amount of fuel (45 g, maybe a few less), but I boiled 3 L of water in about 9.5 min this time. This was with the canister inverted the entire time (I had just rotated the connection and this was my test for leaks). It was cooler today, but water had no ice added. This time of course I used a lid.

Perhaps closing the valve a bit would have saved some fuel as it still seems to have no effect on the flame or sound after about 3/4 turn. I suspect the valve orifice is the limiting factor at that point. I did notice the delay with the canister inverted, which didn't occur when it was right side up. Anyway, I think 3 L in 9.5 minutes is likely normal performance. Not sure about how much fuel that should take though.

One other variable this time was I was using a partial 8 oz canister rather than a new 4 oz one from before. Both MSR brand so that SHOULD not make any difference.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Lids on 09/21/2009 23:13:07 MDT Print View

Hi Tony

> warmer ambient temps the lid made very little difference but at cooler temps it did.

I was testing out a canister stove some years ago - not sure which one. I had it on a very low simmer, and just for the fun of it I tried running the rig with no lid. The water got to ~90 C and sat there. It would/could not get any higher. (Yes, the stove could do a very nice simmer.)

So after about 2 minutes just sitting there I stuck the lid back on. It shot up to boiling quite quickly.

I repeated the experiment with and without the lid after turning the stove off at 100 C. The difference in rate of cooling was very significant.

Cheers
-20 C - hum ... :-)

Hikin' Jim
(hikin_jim) - MLife

Locale: Orange County, CA, USA
Re: Re: Re: Re: Re: Re: Heat Exchanger Stoves" on 09/22/2009 01:14:25 MDT Print View

Roger Caffin wrote >

Hi Jim

You didn't ask about wisdom.

My tests show the neoprene cosy has virtually no effect on the heating rate. But a lid has an enormous effect.

Cheers
lol. Well, I suppose I didn't ask about wisdom did I.

Interesting. Doesn't at least the neoprene prevent heat loss while say, simmering? Or is the neoprene just a very fancy pot protector?

Speaking of lids, that's a big gripe I have with the GCS pot lid. It pops off and doesn't stay fully sealed when it gets hot. I just set it on top rather than fully sealing it, which is probably going to trap most of the heat I'd lose through evaporation (which I believe is the major component of heat loss), but for such a fancy and none-to-cheap pot you'd think they could have a better lid.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Re: Re: Re: Re: Heat Exchanger Stoves" on 09/22/2009 02:39:58 MDT Print View

Hi Jim

Well, all my tests suggest that the neoprene cozy is just another marketing gimmick, at least when you are using a stove of reasonable power. It ?might? be of some use when using a micro open alky and taking 15 min to boil a litre ... maybe.

Yeah, I know, 'all' the stove companies include a neoprene cozy these days, and surely they wouldn't try to sell you something you don't really need? Ahem. (But the cozy can take a huge logo screen-printed on it...)

Actually, with the titanium pots like the MSR Titan series, the heat conductivity is so low going up the side wall that there is not a lot of heat loss from there anyhow. I can grab the top edge of my 1.3 L Titan pot quite happily, so convection-based heat loss from the side walls is not going to be real great. Thick-walled aluminium pots might lose a whisker more, but what BPL member uses thick walled pots? The thin walled HAA pots should not lose too much heat from the side walls, I think, but I need to actually measure the heat loss before saying any more. (Tony may have done this already?)

Cheers

Hikin' Jim
(hikin_jim) - MLife

Locale: Orange County, CA, USA
To Neoprene or not to Neoprene. on 09/22/2009 11:50:18 MDT Print View

So it makes little difference in terms of fuel used and time taken whether one cooks with a neoprene cozy or not? Lol, the things they'll do for marketing. Well, at least on the JB PCS I suppose it helps to keep from burning one's hands when holding the pot/mug. Speaking of which, it seems like if the sides of the pot feel hot to the touch, they must be losing heat, yes? But it's just insignificant, is that it?

How about with multi-step meal preps where I might need to set the heated pot aside for a time while I work on antother step? Would a sitting pot benefit any from the cozy?

Maybe I'm really stretching here, loooking for some shred of value for the neoprene. :) Maybe I should just peel it off and save the weight.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: To Neoprene or not to Neoprene. on 09/22/2009 16:43:10 MDT Print View

Hi Jim

> if the sides of the pot feel hot to the touch, they must be losing heat, yes? But
> it's just insignificant, is that it?
I assume that you have a windshield around your pot. In that case the air coming up the sides between the pot and the windshield is probably hotter than the pot.

> Would a sitting pot benefit any from the cozy?
I do this myself, and yes, some insulation may help. Two buts:
* I find that the contents of my Ti pot are still hotter than I can comfortably eat after 10 minutes standing
* There are much lighter ways to insulate a pot than a neoprene cozy. I often use my bush hat - zero extra weight.

> Maybe I should just peel it off and save the weight.
Well, you could run some experiments with a thermometer. See what works for you. Don't just trust me!
(But do always question what the vendor claims!)

Cheers

Hikin' Jim
(hikin_jim) - MLife

Locale: Orange County, CA, USA
Re: Re: To Neoprene or not to Neoprene. on 09/22/2009 18:09:42 MDT Print View

Roger Caffin Wrote: >

I assume that you have a windshield around your pot. In that case the air coming up the sides between the pot and the windshield is probably hotter than the pot.
Which brings up another thought. If one is using a windscreen and the air moving up the sides of the pot is hotter than the pot itself, then the neoprene might actually be decreasing the amount of heat getting to the pot. lol.

At this point we're probably talking about hairs too fine to split. I guess the general ideas is that the neoprene isn't particularly essential.

Huzefa Siamwala
(huzefa) - M
To Neoprene or not to Neoprene. on 09/24/2009 05:57:13 MDT Print View

I think cozy would be of significant benefit only when using jetboil outside the vestibule in wind without windscreen.

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: Re: Re: To Neoprene or not to Neoprene. on 09/29/2009 00:57:57 MDT Print View

Part 1: It is often assumed that using a windshield it directs the heat from the flame up the side of the pot and therefore the sides will absorb heat into the water, this may be so with some stove systems but this may not necessarily be so with all stoves systems at all settings.

I have just run some tests measuring the gas temperatures up the sides of a pot with and without a wind screen and at different valve settings.

These tests are far from comprehensive and only one test per setting was conducted, a comprehensive set of tests would take more time than I have available to me at the moment.

Stove used a Kovea Supalite Titanium. Pot used a Snow peak Ti 1liter, Windshield very old modified MSR Whisperlite.

The first tests where done with a suspended windscreen that covered the pot and burner, The canister was not covered, the windshield was placed around the pot with about 1-1.5cm gap and the hot gas temperature probe was placed at the top to measure the hot gasses coming out the top gap (see picture 1).

Probe position WS
Picture 1

The tests where done in my garage under windless conditions at an ambient temperature of around 10C.

Results Windshield

Graph 1
Chart 1

Three tests where done using different control valve settings, slow, medium and fast, the medium setting as around what I use in the field.

Slow setting: 6.2g/80C, 10m 45s/80C.
Medium setting: 6.3g/80C, 5m 20s/80C
Fast setting: 7.2g/80C, 2m 59s/80C

Results: with the slow test the gas temperature did not raise much above around 40C, there is some evidence in the gas result line that the gas temperature is actually rising as the water temperature rises therefore it maybe taking heat away from the water in the pot.

The same could be said for the medium test but to a much lesser extent.

With the fast test some heat would be absorbed into the water from the sides but more gas was used.

Note that in all tests the gas temperature measured went up and down randomly, I am not sure exactly what is going on but I think that cooler air is being entrained with the hot gasses.


With chart 2 the probe was placed in three places and temperatures recorded, the first was with no windscreen (No WS top HR and No WS top gas) and was placed at the bottom of the pot 15 mm from the bottom 3 mm from the side (see picture 2), the second (No Ws bott HR and No WS bott Gas) also with no windscreen the probe was placed at the top (picture 3) 3 mm from the sides, the third placing was with a windscreen and the probe was placed at the top as per tests in graph 1.

pic 2
Picture 2

pic 3
Picture 3

graph 2
Chart 2: HR= heating Rate, Gas = gas temperatures.

WS top setting: 6.3g/80C, 5m 20s/80C
No WS top setting: 6.2g/80C, 5m 10s/80C
No WS bottom setting: 6.5g/80C, 4m 45s/80

With all three tests the settings where set at about what I would set the stove in the field (this is not exact science but with canister gas stoves it is very difficult to exactly to repeat tests.)

Results: It can be noted that with the top placed probes the measured gas temperature where lower than the bottom placed probe , my thoughts on this is that as the hot gas travel’s up the sides it mixes with the cooler surrounding air cooling the gas down, surprisingly this also happens when the windshield is used some of this heat loss my be from contact with the windshield but my guess is that as the hot gasses travel up th sides it entrains cooler air.

When I find time I will do some similar tests with my flux ring pot to look at the gas temperatures up the sides and to see if I can see if using the neoprene cozy makes any difference.

Conclusion: As pointed out in my earlier discussions these tests are not comprehensive but they show that in a windless environment using a windshield makes very little if any difference to the efficiency of a canister stove system, in a windless environment the main influence on efficiency is the valve setting

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Re: To Neoprene or not to Neoprene. on 09/29/2009 04:14:32 MDT Print View

Very interesting! Thank you Tony.
Makes sense - although I don't often have a windless environment!

Cheers