Steve,

I'll take you word on that! Come to think of it, I don't work so well at -20 either!

I did this mod to my hanging jetboil. I need to figure out a better way to hold the fuel inverted, the tape will not work well on a 4 day trip. Also, what is the best way to minimize the flare up that occurs when you first invert the fuel. I got a fire ball the first time I used this, that singed the cozy.

Edited by tkknc on 06/13/2008 16:04:27 MDT.

Hi Ken

> what is the best way to minimize the flare up that occurs when you first invert the fuel.
Options:
1) Start very low and let the stove warm up for 15 - 30 seconds.
2) Start with canister upright, and invert after maybe 20 seconds.
But it isn't a really good stove for doing this with anyhow as the thermal feedback is not good.

Reckon a couple of bits of light string might be fine for holding the canister instead of the tape, or even a 'hammock' of fabric off the corners of the hanger.

Cheers

Has anyone ever experimented with converting a Simmerlite? I quite like the pot stability, as opposed to a PR on a Brunton, plus I already own a Simmerlite. Would it be viable to rig a block to screw onto a canister and then plug in the Simmerlite fuel line.

Roger wrote


Actually, the preheat tube on the WindPro is excessive, but the stove is simply a converted SimmerLite.

> Would it be viable to rig a block to screw onto a canister and then plug in the Simmerlite fuel line.
Of course.
The details are left as an exercise for the reader ... :-)
(But have a look at Tony B's recent postings.)

You might need a slightly larger jet with the gas.

Cheers

To revive an old thread:

Is there a functional minimum temp as to what temp a modified stove can handle? Is there any qualms about using a modified can stove as a serious snowmelter? Thanks.

Hi Matt, I left this post on page 2

"I use an inverted windpro for winter aswell, but when the temps drop really low (-20 ish) it still seems to suffer. Not sure if it is the fuel or if it is just so dang cold that it takes forever to heat the water?!"

After last winter, I am no longer going to use the inverted windpro canister as a snow melter as it just isn't performing for me. This could be the stove, perhaps temps are just too low, or maybe it's just me! I have no test data (or scientific explanation) other then when it gets real cold, -20C or so, it really struggles. It literally starts to take forever to melt snow and you can see that the flame output just isn't there.
I'm going to experiment with some wood burning stoves this season to see if I can get some decent results.

Hi Matt and Steve

> Is there a functional minimum temp as to what temp a modified stove can handle?

Yes. A 30% propane 70% butane canister will stop emitting gas at about -26 C. Laws of physics. What Steve found was about right, especially if the canister had less than 30% propane.

However, just because this is so does NOT mean you can't use a remote inverted canister stove under far colder conditions. You certainly can do so with just a little effort.
Step 1: Warm the canister inside your jacket for a while (You will be wearing one, right?).
Step 2: Start the stove running and quickly invert with the canister.
Step 3: Quickly warm a LITTLE bit of water to LUKE-warm body temperature.
Step 4: Pour this LUKE-warm water into the bowl made by the inverted base of the canister, and insulate the canister. (If using a Coleman Powermax canister, get creative.)

What you are doing here is adding heat to the canister from the LUKE-warm water to keep the gas above 0 C. This will make the stove work just fine. The canister does not have to be at ambient, after all.

Two notes to remember:

1: Do NOT use water any warmer than LUKE-warm! I really mean this. But equally, LUKE-warm water is perfectly safe.

2: Prevent the water from cooling fast by insulating it and the canister by blocking the loss of steam or water vapour. Otherwise the water will cool down quickly and turn to ice, mainly by evaporation.

Cheers

Edited by rcaffin on 10/26/2008 03:53:43 MDT.

"2: Prevent the water from cooling fast by insulating it and the canister by blocking the loss of steam or water vapour. Otherwise the water will cool down quickly and turn to ice, mainly by evaporation."

As in wrapping the canister with sleeping pad material and covering the "bowl" with the water in it with a piece of silnylon or something?

I do remember when I used to use an upright canister that when the water would boil over and spill onto the canister, the canister would suddenly have a bolt of energy and work much better for a few seconds.

Also, I'm just curious of your experiences, but how many times would you have to replace this luke warm water? Every minute? or is it every 10 minutes...tying to figure out the PITA factor :)

Thanks Roger.

Thanks for the thoughts - I'm probably going to make this in the next few weeks and use it for at least fringe seasons. I have been using a Dragonfly for my primary winter snowmelter, but I would love to shave 10 oz off my winter stove weight.

Hi Steve

> As in wrapping the canister with sleeping pad material and covering the "bowl" with the water in it with a piece of silnylon or something?

Anything like that. A 'cozy' covering the top and sides and made from bubble wrap would probably do. Just stop that evaporation!

I gave Sue some luke-warm water one morning in the snow so she could wash our plastic breakfast bowls out. She rinsed them clean, put them down wet and went looking for our mini-teatowel to dry them. By the time she had found it, the water left in the bowls had frozen! All she had to do was tap the plastic bowls so the ice fell out, and they were dry. Thus evaporation heat loss!

Another way of handling the problem is to leave the windshield around the stove open for a few inches and to position the canister near the opening in the windshield, so it gets a bit of the hot air and radiation from the stove. Needless to say, with this trick you MUST sit there and monitor the temperature of the canister. Luke warm is what you want; hot is absolutely NOT.

How much hot water, replaced how often? Depends very much on the conditions (and any evaporation loss). The key thing to remember here is that there are huge differences between using an upright and an inverted canister, thus:
* With an upright the gas is boiling inside the canister and the energy for this comes from the canister - so it chills down fast. You have to keep pumping in more energy or the canister will chill too far to boil.
* With an inverted canister there is almost no evaporation at all inside the canister: it happens at the stove using heat from the flame. So the canister does not chill down quickly. Get it warm and it will stay warm, barring external heat loss.

Cheers

It is really to bad this site has no real search function. There are so many great MYOG threads hidden away in the closet here.

Or could it just be lazy members?


Make A Canister Cozy 08-24-2005

The wheel just keeps getting re-invented and re-invented.

Inverted Canister Stove - 01/04/2006


Inverted Canister Stove

Roger-

I guess this is a more appropriate thread for questions about the gases--

* With an upright the gas is boiling inside the canister
then
With an inverted canister there is almost no evaporation at all inside the canister:

I'm feeling slow here. But this is comparing two different things, right? Boiling in one canister, evaporation in the other? Except the gases couldn't actually evaporate unless they escape the canister, right? I asked on the other thread if the simple inversion of the canister actually changes the physics and separation of the gases--this makes it sound like it does! I sure like the sounds of it staying warm once warmed, though.

Bill, I don't think it has anything to do with lazy members. I know I've read all the old pertinent threads--shoot, everyone's remote canister set-ups and your Balrog inspired me to start creating my own! But I like how conversations here continue to develop and explore things from slightly different angles, too.

Hi Brad

Replied on other thread. Yes, quite different fuel delivery systems.
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=16401&disable_pagination=1

You are right about the confusing use of 'boiling' and 'evaporation'. I use 'boiling' to mean that lots of vapour is coming off, as in an upright stove or water boiling in a pot. With an inverted canister there is a high internal pressure from the gases, but the vapour at the top of the canister does not escape. I used 'evaporation' for the process of creating the pressure: it is similar to pumping a WG fuel tank.

Cheers

I thought that I would share this with you all. One thing that was lacking here was a convenient way to invert the canister. I took a canister stand made by Primus and adapted it to work with the Brunton stand. The design of the Primus stand worked well here because I was able to center the canister attachment part of the Brunton stand on the top leg since the leg itself comes out from the side. Basically what I did was:


1 – Use a round file to file a groove in the top Primus leg to fit the top of the canister adapter


2- Used some epoxy to glue the adaptor to the leg.


3 – Removed the excess plastic from the other legs so that it all would fold together.


4 – Finally I used a zip tie to minimize the stress on the epoxy.

The weight of the Brunton stand was 5.4 oz. The total weight when I got done was 6.0 oz. I did file some of the excess metal from the steel legs from the stand for the stove.


Here is what it looks like all folded up (yeah it is a big screw isn’t it).

I put everything together, and am having a few problems. I am using an MSR PocketRocket, but that shouldn't matter. My block parts and fin were made of brass, the screw was steel. The blocks were made it out of one piece of brass and drilled the holes before cutting it in half. The rod I put inside the brass tube was about 1.8 or 1.9 mm. There is a slight gap between the blocks (more so on the top). I was using Snow Peak canisters, and all of my testing was done in temps in the mid to low 20s (F). I did however, throw the canisters in the freezer to cool them and better simulate winter conditions before the testing began. Each test lasted about 10 minutes.

I cannot get the gas to vaporize properly. When the canister is upside down, I get a continuous fireball, even on very low power. Even after the stove heats up and the upright fin appears to be warm, but it does not appear to be vaporizing the gas.

To try to correct this, I added some thermal compound between the blocks and between the fin and one of the blocks in an effort to increase heat transfer. This did not work, and the stove never settled down.

Also, I can settle the flame be leaning the canister slightly while upside down. I am using mostly-empty canisters. However, as soon as I tip the canister fully upside-down, the stove fireballs again.

As I see it, I can cut a new blocks and hope for a better fit and/or make the fin out of copper to increase heat transfer. I also think I should add a thicker rod inside the brass tube to decrease gas flow.

Any suggestions?

Edited by citystuckhiker on 11/18/2008 20:01:10 MST.

Wow!
Elegant!

Roger

Hi Matt

> When the canister is upside down, I get a continuous fireball, even on very low power.
> Even after the stove heats up and the upright fin appears to be warm, but it does not appear to be vaporizing the gas.
> My block parts and fin were made of brass

I have had this problem myself too. I found that the brass strip I had installed was simply not conductive enough. I swapped over to a copper strip (lying on the bench ...) and the arrangement worked fine.
Have a look at this page
http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html
You will see that the thermal conductivities of relevant metals are:
Brass 109 W/(m.K)
Aluminium 255
Copper 400

Brass is only 1/4 as conductive as copper. So while using brass for the solid block is OK, you have to use copper for the fin. You could try thick aluminium if you like (1/16" maybe) but there is always the risk of melting it.
You could also try a hard Al alloy for the block if you have some.

> I also think I should add a thicker rod inside the brass tube to decrease gas flow.
Secondary imho.

Cheers
Roger

Thanks - I'll make the fin out of copper and report back.