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#220120 - 03/24/11 02:18 AM Some testing of heat exchanger pot (eta power)
jzmtl Offline
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Registered: 03/18/10
Posts: 530
Loc: Montreal Canada
I put my new Primus 1.0L eta pot to the test against a regular kitchen pot. Both are heated with a MSR pocket rocket running on almost full can of Primus gas, with 0.5L of tap water. Eta pot also has the Primus clip on windshield, thou the test was conducted indoors (too cold outside for upright canister stove), so it may only function as a poor heat reflector.

Regular stainless kitchen pot came to rolling boil at 2 minutes and 15 seconds, eta pot came to rolling boil at 1 minute and 45 seconds. So in the end that's only 30 seconds of time saved, or around 25% efficiency increase, a far cry from Primus' claim of 50%.

The price of Eta pot is about 60% higher than Primus litech, which is essentially the same stuff without heat fin, and perhaps even closer to eta's efficiency compare with the stainless kitchen pot.

So is it worth it, I don't know, from pure cost saving POV it's going to take a whole lot burn to make up the price difference. But on the other hand you can squeeze a few more boil/meal out of the same fuel canister when there is no spare, and that could come in helpful depends on the situation.

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#220127 - 03/24/11 02:39 AM Re: Some testing of heat exchanger pot (eta power) [Re: jzmtl]
Teslinhiker Offline
Veteran

Registered: 12/14/09
Posts: 1389
Thanks for the tests / review.

I have the Primus Litech Kettle / pot and really like it. When I purchased it about 2-3 years ago, I also looked at the EtaExpress pot you tested and decided at the time, that the addition of the heat exchanger and subsquent extra cost was not worth the investment to gain only 10's of seconds of claimed heat time.
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Earth and sky, woods and fields, lakes and rivers, the mountain and the sea, are excellent schoolmasters, and teach some of us more than we can ever learn from books.

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#220149 - 03/24/11 10:19 AM Re: Some testing of heat exchanger pot (eta power) [Re: jzmtl]
hikermor Offline
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Registered: 08/26/06
Posts: 6857
Loc: southern Cal
Thanks for the figures. I suspect the difference would be even less if your standard pot had a typical cobbled up, aluminum foil wind screen, not as highly efficient, but light, cheap, and versatile.
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#220159 - 03/24/11 01:36 PM Re: Some testing of heat exchanger pot (eta power) [Re: jzmtl]
Am_Fear_Liath_Mor Offline
Carpal Tunnel

Registered: 08/03/07
Posts: 3078

Thanks for the review, it confirms typically the same 25-30% improvement in fuel consumption that I have found for gas burners of a medium heat output such as the MSR pocket rocket. I have found that slightly higher efficiency (by comparison) is available using the 1.7 litre pot with gas burners with much higher output such as the Coleman F1 Power stove, which will produce almost twice the heat output of the MSR pocket Rocket. Using conventional pans with the Coleman F1 at the maximum heat output tends to send a lot of the heat up and around the pan, where as the Primus Eta Power seems to 'capture' the heat much more effectively giving boil times less than 1 minute for 0.5 litre of water.

Typically if you can get around 12 Litres of Boiling water with a conventional SS pan and an 220 gm cartridge the 25% improvement in efficiency will get an you an extra 3.75 Litres giving almost 16 Litres in total. Thats equivalent to an extra day or two in cooking capability out in the wilderness all for an extra 40 grams of heat exchanger.

With the larger 500 gm cartridge the differences are even greater giving an extra 3-4 days extra cooking/boiling capability.

The 1 Ltr Etapower pot is certainly appears to be lot more expensive to purchase since they initially appeared on the market though. The Etapower 1.2 Litre pot is available for much less cost though.

http://www.amazon.com/Primus-Eta-PackLite-Litre-Colander/dp/B003EM75EK/ref=pd_sbs_sg_5

Rather than spending around $58 for the 1 Litre Etapot I would spend the extra $15 and get the EtaPacklite stove system instead.

http://www.amazon.com/Primus-354083-PACK...155&sr=1-15

http://www.youtube.com/watch?v=JF-TxE20m9c

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#220160 - 03/24/11 02:01 PM Re: Some testing of heat exchanger pot (eta power) [Re: hikermor]
Hikin_Jim Offline
Sheriff
Pooh-Bah

Registered: 10/12/07
Posts: 1804
Loc: Southern California
In an indoors test, a windscreen won't make too much difference unless it can be made to function as a skirt where hot air is channeled up along the sides of the pot.

In the field, in wind, I'd take a windscreen over a heat exchanger pot pretty much any time unless the particular heat exchanger pot were to provide some wind protection. The Jetboil PCS offers some, and the MSR Reactor offers a lot of wind protection.

On the other hand, a Jetboil GCS's heat exchanger is exposed. Heat exchangers cut both ways. A strong wind can suck heat out via a heat exchanger just as much as a flame can put it in. I've read posts where a person burned an entire canister of gas but couldn't get their water to boil.

Manufacturers typically say "never use a windscreen with an upright canister stove." Of course those warnings are primarily to prevent lawsuits. The reality is that in temperate conditions, a windscreen with something like 270 degrees of coverage around a canister stove probably won't overheat a gas canister if you know what you're doing, particularly if it's windy.

The trick is to feel the canister. If it feels hot (hot, not warm) to the touch, then you need to take immediate corrective action. As long as the canister is no more than warm, then it's perfectly safe to use a windscreen. You just need to be diligent and repeatedly feel the canister. This is not something that you light and then go set up the rest of camp while dinner cooks. You need to feel the canister and keep a close eye on things.

In cold weather, you can go with a lot more coverage, probably more like 315 degrees of coverage, just leaving enough gap that you can adjust the flame. The heat of the flame can work to your advantage, keeping the gas in your canister warm.

Using a windscreen with an upright canister stove is not without risk. If you know the risks and are a diligent person, you shouldn't have a problem. If you're easily distracted, maybe you shouldn't use a windscreen with an upright canister stove. For the easily distracted, a remote canister set up can be used with a windscreen and will never need checking. The windscreen with a remote canister set up protects the fuel from the heat rather than transferring heat to the fuel.

I've got an article coming out in the April edition of Seattle Backpacker's magazine that will discuss remote canister stoves further.

The times where it might be really worthwhile to have a heat exchanger pot are:
a) Snow melting. Snow melting can take a long time. If you have a certain amount of time alloted before you turn in for the night, it may be worth it to have a heat exchanger pot so that you can get everything done in the time between the time you arrive at camp and the time you need to turn in. In really cold weather, your sleeping bag may be the only thing able to keep you warm enough. You don't want to spend a lot of time outside the bag messing around with melting snow.
b) Big groups. If you're cooking for big groups, you may have larger quantities of water to boil or food to cook. A heat exchanger pot can certainly speed things up.
c) Fuel availability restrictions. Say you're doing a longer hike. You need your fuel to last "X" number of days. A heat exchanger pot might help you do that. On a Sierra backpack in 2009, I got by with about 100g (one 4 oz canister) of gas for five days for three people (four hot suppers, four hot breakfasts, cold lunches). That's 25g of fuel per "day," (day = 1 breakfast + 1 supper) which is pretty danged good. I was using a Jetboil GCS (which has a heat exchanger pot) and a windscreen.

HJ
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#220176 - 03/24/11 03:59 PM Re: Some testing of heat exchanger pot (eta power) [Re: jzmtl]
jzmtl Offline
Addict

Registered: 03/18/10
Posts: 530
Loc: Montreal Canada
That's one of the reasons I picked the primus windshield, it will not reflect any heat down to canister, and everything in the photo will pack into the pot with room to spare.


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#220209 - 03/24/11 08:28 PM Re: Some testing of heat exchanger pot (eta power) [Re: jzmtl]
Hikin_Jim Offline
Sheriff
Pooh-Bah

Registered: 10/12/07
Posts: 1804
Loc: Southern California
I'm not so sure about that windshield. I notice that I can see the heat exchanger over the top of the windscreen.

On the plus side, I don't think that it would cause any heating of the fuel.

HJ
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#220210 - 03/24/11 08:40 PM Re: Some testing of heat exchanger pot (eta power) [Re: jzmtl]
jzmtl Offline
Addict

Registered: 03/18/10
Posts: 530
Loc: Montreal Canada
Yes some heat exchanger is exposed but burner isn't. Now that you mentioned it I see the problem, looks like I need to tweak it more.

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#220213 - 03/24/11 09:08 PM Re: Some testing of heat exchanger pot (eta power) [Re: jzmtl]
Hikin_Jim Offline
Sheriff
Pooh-Bah

Registered: 10/12/07
Posts: 1804
Loc: Southern California
One problem might be that the windscreen was designed to work with the Primus Eta Express stove. The burner height on a PR might be different. If the burner height on a PR is higher, then the windscreen might not reach high enough. I would think that for sure you'd want to have the windscreen go a little higher than the top of the heat exchanger. You could extend the windscreen a little bit with a couple of paper clips and heavy gauge aluminum foil or similar material. It wouldn't be pretty, but when you're hungry, who thinks about how pretty their stove is?

HJ
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#220268 - 03/26/11 02:27 AM Re: Some testing of heat exchanger pot (eta power) [Re: jzmtl]
jzmtl Offline
Addict

Registered: 03/18/10
Posts: 530
Loc: Montreal Canada
I've tried additional windshield by adding piece of aluminum to cover the heat exchanger. It actually made efficiency lower, boiling is back to 2 minutes. I think because the shield is so close to the pot, it's interfering with airflow through the fins, which they need in order to function properly.

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