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David Buto
(Booterman) - F
Monatauk Gnat Stove Review on 07/05/2010 05:18:05 MDT Print View

How does the Gnat stove performance compare to the Soto OD-1R Micro Regulator Stove in terms of maintaining consistent output in cold weather? Although many stoves may seem alike, the Soto appears to have an edge in performance as temp drops and as fuel runs out, i.e., the Soto output is the same across the spectrum.

Andrew Wolff
(Andrew) - M

Locale: Chattanooga
Gnat Stove on 07/05/2010 14:15:10 MDT Print View

"the expedition-conscious ultralighter can turn down the fuel power and eke out thirty-six to forty boils (at 12 oz/boil) without much difficulty" What sort of altitude are we talking about here? I imagine there's quite a large variation in how long a canister lasts between say 10000 feet and sea level.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Gnat Stove on 07/05/2010 16:06:52 MDT Print View

> I imagine there's quite a large variation in how long a canister lasts
> between say 10000 feet and sea level.
No, altitude will have very little direct effect on the life of a canister. The canister supplies energy, and how much energy is in the canister is unrelated to altitude.

However, because the ambient temperature drops as you go up in altitude, you will find yourself using a little more fuel to get water up to 80 C. On the other hand, water boils at a lower temperature at higher altitudes, so you will need a little less fuel to go from 80 C to boiling. Ho hum ... :-)

Anyhow, most of that is irrelevant. What really influences practical fuel consumption is wind, use-of-windscreen, heating rate, lid-on-pot, and other things like that. They are far more significant, to the point of being totally dominant.

Cheers

Frank Deland
(rambler) - M

Locale: On the AT in VA
giga on 07/06/2010 22:04:03 MDT Print View

The Snow Peak Giga weighs 3 oz., but that includes the "ignitor". You have to weigh in whatever it is you use to light the Gnat stove.

Edited by rambler on 07/06/2010 22:04:39 MDT.

carlos fernandez rivas
(pitagorin) - MLife

Locale: Galicia -Spain
ignitor on 07/07/2010 06:47:40 MDT Print View

not really, ignitors fail so frecuently that you MUST to carry one lighter anyway

John S.
(jshann) - F
Re: ignitor on 07/07/2010 07:41:50 MDT Print View

Agree with Carlos. You still have to carry a lighter/matches. We had a jetboil piezo ignition fail this past weekend in the Pecos Wilderness.

Roger B
(rogerb) - MLife

Locale: Here and there
Re: Re: ignitor on 07/07/2010 08:52:13 MDT Print View

I have never purchased a piezo ignitor stove, preferring to use a mini lightmyfire striker instead, which can also be used to start a "fire" in the old fashioned way as well.

John Hurley
(backpacker56) - F

Locale: Central Texas
Titanium = Corrosion Resistance on 07/23/2010 14:24:51 MDT Print View

No one has said anything about the corrosion resistance of titanium.

Is the burner itself titanium? How does it look after it's been fired a few times? I've seen used non-titanium stoves of similar type for sale (ebay) and the burner is all rusted. May still work okay, but aesthetics are important too. Charred, rusty stoves are ugly. If this stove avoids that, it should score points.

On the other hand, some parts are aluminum, how well do these parts hold up?

Stuart R
(Scunnered) - F

Locale: Scotland
What's wrong with my Gnat? on 08/17/2010 14:23:19 MDT Print View

When first lit, my Gnat burns a blue flame, but after 30 seconds it turns orange.

Gnat flame

Anyone else experience this?

Does it matter?

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: What's wrong with my Gnat? on 08/17/2010 14:37:38 MDT Print View

As a general rule, if the flame color is different from what you expect, then there is a problem of some sort. If the flame is supposed to be blue-hot and it is only orange-hot, then that suggests a "breathing" problem, like if the cold air intake is clogged with foreign material. It is possible that the fuel is contaminated with something, but with a butane canister stove, that would be very unlikely. It is possible that there is some foreign contamination in the top of the burner, like spilled food. The top of the burner is normally titanium or stainless, so it does not corrode even after serious heat. Those metals might change color slightly, but that is normal.

--B.G.--

Stuart R
(Scunnered) - F

Locale: Scotland
Re: Re: What's wrong with my Gnat? on 08/17/2010 14:44:26 MDT Print View

Bob

The same canister wth a different stove is fine, so not fuel contamination.

I took the burner apart to look inside. The burner is titanium with a fine mesh (presumably stainless steel) inside. No dirt. The jet looked ok although I didn't remove it as I may want to return the stove.

The flame starts off blue as I would expect, but turns orange once the stove has heated up, about 30 sec

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: What's wrong with my Gnat? on 08/17/2010 15:03:36 MDT Print View

On most of these stoves, the cold air intake is a pair of open holes on the sides and between the fuel port screw and the burner. Did you poke around in there? One tiny bit of leaf could really clog things this way.

--B.G.--

Stuart R
(Scunnered) - F

Locale: Scotland
Re: Re: Re: Re: What's wrong with my Gnat? on 08/18/2010 01:41:01 MDT Print View

Bob

This stove is brand new, fresh out the box.
There is no accumulated dirt and no obvious bits of swarf anywhere I can see.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: What's wrong with my Gnat? on 08/18/2010 04:59:47 MDT Print View

Hi Stuart

Same problem as we discussed before.
But I don't think mine does that ... what happens when you turn the power up?

cheers

Stuart R
(Scunnered) - F

Locale: Scotland
Re: Re: What's wrong with my Gnat? on 08/18/2010 06:55:06 MDT Print View

Hi Roger

Similar problem as previously discussed - *some* part of the burner must be getting too hot.

The only part glowing visibly are the pot supports. However, the 'windscreen' on a Pocket Rocket also glows but doesn't result in an orange flame, so I don't think that is the problem.

So, it must be something inside the burner? I had a quick look and saw nothing obviously wrong, but I'll take another look.

The power is already quite high in the photo, turning it right up doesn't make much difference.

I didn't see any video reviews of this stove showing this problem, it must be just me :-(

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: Re: Re: What's wrong with my Gnat? on 08/18/2010 10:33:22 MDT Print View

Stuart,

I found this in a gear review of the Gnat on Backpacker.com.

>>Two tips: 1) Don’t forget to pack your own windscreen because the burner is very susceptible to breezes, and 2) Screw the canister on tight. (I noticed a big difference in output between a lightly screwed on and a cranked on canister.)<<

How close is the aluminum control valve housing to the "rim" of your fuel cannister? Does it contact the rim of the cannister as you are attatching the stove to the cannister?

The change in the color of the flame suggests to me a change in the air fuel ratio. Is it possible your are going to a "lean" mixture of air and fuel due to the fuel cannister not being firmly attached and fully open at the self sealing cannister valve?

Compare the parts of the two stoves that connect to the cannister. Is the part of the Gnat that opens the self sealing valve on the cannister clean and able to fully open the self sealing cannister valve?

Looking at pictures of the Pocket Rocket stove I notice a seal of some sort between the stove assembly and the fuel cannister. Is it possible that the Gnat is "drafting" excess air into the fuel mixture at the cannister / stove connection?

I am very interested in this thread as I am contemplating the purchase of a Gnat/Fire Maple stove myself.

Party On,

Newton

Stuart R
(Scunnered) - F

Locale: Scotland
Re: Re: Re: Re: What's wrong with my Gnat? on 08/18/2010 14:53:45 MDT Print View

John

"How close is the aluminum control valve housing to the "rim" of your fuel cannister?"

Gas starts to come out of the canister when the clearance from the control valve housing (the orange bit) to the canister rim is 0.3 - 0.4mm for two different canisters.
The stove then screws on for a further 0.3mm without excessive force.

I think the seal between canister and stove is good. In any case, a bad seal here would result in gas leaking out, not air leaking in.

I took the stove apart again and had a good look, but still didn't notice anything obviously wrong.

Ho hum

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: Re: Re: Re: Re: What's wrong with my Gnat? on 08/18/2010 16:10:53 MDT Print View

Stuart,

Are all other parts of the stove above the orange "valve bit" assembled tightly before and after the testing? Excess air in the mixture?

Can there be anything blocking the flow of gas to the jet/burner? Pressure of the fuel being delivered to the burner reduced? A part of the cannister seal?

Is there anything that can be causing a catalytic reaction of the flame where you are testing the stove? The color change?

Party On,

Newton

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: What's wrong with my Gnat? on 08/18/2010 16:19:44 MDT Print View

Hi Stuart

OK, I got mine out and fired it up. It started out with a blue flame as should be, but as the middle of the Ti pot supports bits got red hot it gradually developed the orange colour you showed.

Diagnosis:

The red-hot metal at the burner face is causing a change in the chemistry of the flame, with atomic carbon being generated too early for combustion. The carbon atoms are glowing in the flame as the hydrogen is being burnt first. I think most of the carbon does get burnt up higher up. This does not (normally) happen with other stoves when there are no red-hot bits in the flame.

So ... I took the pot supports off and tried the stove again. It lasted longer before getting an orange flame, but the top of the burner face did slowly get red-hot, and then the orange glow returned.

I note that this burner has a double layer of mesh under the Ti burner face. That should stop it from getting any flash-back or internal ignition, and the inner layer is unlikely to get as hot. Field testing has not shown any problems of flash-back either.

You can 'improve' the performance (ie reduce the orange glow) by *restricting* the inwards air flow. This makes the flames just a little longer, so they don't heat the burner face as much. The heat is higher up or further away. Blocking one air inlet hole may be enough.

However, as I said, field testing has not shown any problem with this burner, so you could just ignore the problem ***in my humble opinion***.

Cheers
Roger

. .
(biointegra) - MLife

Locale: Puget Sound
Re: Re: What's wrong with my Gnat? on 08/18/2010 17:00:00 MDT Print View

Does it make a difference when there is a pot of water on it heating up? Perhaps the stove will not have a chance to develop much of the orange flame if a pot is on top and the stove is switched off after boiling. That is, perhaps field use will prove to be less enigmatic.