Keggle skirt holes for additional burner venting

Has anyone cut additional holes in their keggle skirts to allow better venting from the burners? The flames on my new stand aren't curling downward, but it appears that the combination of windscreen/frame is interrupting the flow of exhaust gasses. I'm thinking a series of 1/2" holes along the top of the skirt would work, or if i get lazy bigger slots with the angle grinder.

What is the theory on flames curling downward? I think the 4 holes already in the skirt would be enough to let any gas to escape.

As a test on the single tier, i had both burners going toward the low end of output. One burner with keggle, one without. The steel and windscreen around the burner with the keggle all discolored and turned red hot, the burner without the keggle "obstruction" did not.

outside92129 said:

Has anyone cut additional holes in their keggle skirts to allow better venting from the burners? The flames on my new stand aren't curling downward, but it appears that the combination of windscreen/frame is interrupting the flow of exhaust gasses. I'm thinking a series of 1/2" holes along the top of the skirt would work, or if i get lazy bigger slots with the angle grinder.

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Yep, I did and I regret it. It substantially increased the time to bring 5 gallons to a boil. I did a before and after test and did my best to eliminate any other variables. I do not have a windscreen on my burner, but the test was done out of the wind in an enclosed garage with an SQ-14 burner. This was a one time test, so don't take the results as absolute. I may well have overlooked something. The venting concept sounded like a good idea, but I no longer think so. If you do it, run a similar before and after test and post back. I'd be inteested to know if you have the same result.

Catt22 said:

The venting concept sounded like a good idea, but I no longer think so. If you do it, run a similar before and after test and post back. I'd be interested to know if you have the same result.

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I agree.... more information is good.

I think it also depends on the burner you're using... I used my KAB4 under my keg mash tun and didn't have any issue. Well, none from the burner that is...

I've seen a thread here on the exact same subject, only, I can't find it, and I can't remember what the conclusion was (lot of help I am lol). The guy did some before and after measurements with timing how long it took water to boil in the keggle before and after the holes. I think the thread also had some experiments on painting the bottom of the keggle black if that helps to find it?

I just have the original 4 holes in the skirt. Luckily, I turned the keg so they don't face "out" front and back. Flames come out of those holes and will superheat anything around (including shirt tails!) - Dwain

I don't understand why you'd want the heat venting out from under the Kettle.

olsond said:

I don't understand why you'd want the heat venting out from under the Kettle.

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The theory, as I understood it, was that the un-vented skirt would trap gasses which would deflect the incoming hotter gasses preventing them from reaching the bottom of the kettle efficiently. The vents were supposed to allow the cooler gas to be more effectively displaced by the incoming hotter gasses by giving it an easy escape route.

I have used one of these camping pot heat exchangers on a friends camping pot. You might try that concept?

http://cascadedesigns.com/msr/stoves/stove-accessories/heat-exchanger/product

rhoadsrage said:

I have used one of these camping pot heat exchangers on a friends camping pot. You might try that concept?

http://cascadedesigns.com/msr/stoves/stove-accessories/heat-exchanger/product

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Interesting concept... would be more interesting if one of those didn't cost more than a kettle itself.

I've been tossing around in my head how to make heating fins/sink/etc for a keggle in a cost and time effective way, to be able to capture some of the massive amount of lost heat. 6" vertical aluminum fins spaced 1/2" apart would seems ideal... but for a 52" circumference the time cost to fabricate and weld on the bits far outweighs the propane savings. Of course if a TIG welder drops in my lap AND i get bored on of these days i may try it...

Back to my original problem, the BG14's output a lot of gas. I'll see if i can't turn it down some more. I do need to weld up one of the skit holes, i'll pop in a couple more 1/2" holes and will report back in a week or so how it works out.

Any updates on comparisons between before/after venting the skirt Outside???

On my Blichmann burners the flames are lower/smaller but I get much better heat delivery from them to the mash tun keg. I'm actually putting together a keggle (in the process of polishing it) that will be used for my next batch. With four holes before the lower weld, I don't think there will be any issue with gas venting.

IF you do put additional holes in the skirt, you could see a reduction in how efficient the heating of the keggle is. In the new keggle I'm making, it has four holes already in the skirt (placed there by the manufacturer) which I'm leaving alone. Actually, I might see about getting one welded closed since it's really close to the ball valve (in line with one handle opening). IF I do that, I might place a hole in that same area, where it's safe. I just don't want the heat to come through the hole and either scorch the wort in the ball valve, or otherwise F up the hardware going in. An alternate would be to get a small half round (cut stainless tube) welded there to shield the hardware.

Well after reading one of the other posts i chickened out on cutting the side holes. I did weld up one of the vents but it didn't seem to have any noticeable effect. I do have plans to swap out my HLT (13gal) with a bigger one (15.5gal), when i do that i'll do the experiment.

outside92129 said:

Well after reading one of the other posts i chickened out on cutting the side holes. I did weld up one of the vents but it didn't seem to have any noticeable effect. I do have plans to swap out my HLT (13gal) with a bigger one (15.5gal), when i do that i'll do the experiment.

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Roger that. I think the distance from the bottom of the keg to the top of the burner has a big impact... Seems I've read that 4" is ideal. That's what I'm shooting for in my build.

Cheers!

you could try my chimney idea which is working great. the hot gases escspe out one corner and the "Stack Effect" draws the fresh air up from below the burner. here's a link to my build https://www.homebrewtalk.com/f51/single-tier-herms-build-293204/

On a somewhat related note, I made a "chimney" on my old rig which was about 2-3" in diameter larger than the kettle. It slipped down over the outside of the kettle & was nearly as tall. This kept any breeze off of the keg and conducted most of the hot gasses escaping from beneath upwards along the side of the kettle (between the kettle & chimney). It seemed like it helped a lot, but I did not make any before / after measurements. A friend did the same with his and saw improvement. The chimney was a piece of SS round duct found in the scrapyard.

Weld the spear to the center of the keg. Let the flames shoot through the center of your wort. This would give the best efficiency with gas.

passedpawn said:

Weld the spear to the center of the keg. Let the flames shoot through the center of your wort. This would give the best efficiency with gas.

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That's new information to me. I cut a hole in the bottom of a keg, weld the spear and the heat goes up through the center, Not only heating the bottom but also the middle.

iaefebs said:

That's new information to me. I cut a hole in the bottom of a keg, weld the spear and the heat goes up through the center, Not only heating the bottom but also the middle.

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So you've tried this?

I had a SS tube welded into the center of my HLT to conduct some of the hot gasses up through the liquid and it worked fine. I even put a strip of sheet SS with a twist inside to give the gas a little spin or turbulence. I got the idea from a regular gas-fired domestic water heater.... It seemed like there wasn't as much heat washing out from beneath the kettle trying to go up the outside which was insulated.

Junkster said:

I had a SS tube welded into the center of my HLT to conduct some of the hot gasses up through the liquid and it worked fine. I even put a strip of sheet SS with a twist inside to give the gas a little spin or turbulence. I got the idea from a regular gas-fired domestic water heater.... It seemed like there wasn't as much heat washing out from beneath the kettle trying to go up the outside which was insulated.

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Any pictures by chance?

passedpawn said:

Weld the spear to the center of the keg. Let the flames shoot through the center of your wort. This would give the best efficiency with gas.

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Brilliant!! Ive gotta see this? Pics??

I could only find a few pics - I sold that rig last year. As I recall, we made a hole in the bottom of the keg just large enough for the tube to pass through and fuse-welded it to the bottom with a TIG machine. You can barely see the underside in one of the pics. I made a restrictor from a SS washer to sit on top of the flue to keep the flames from shooting out of the top. The lid has a flap that slides open to let the gasses out & to help keep the heat in when the burner is off. I hope this helps.....

Junkster said:

I could only find a few pics - I sold that rig last year. As I recall, we made a hole in the bottom of the keg just large enough for the tube to pass through and fuse-welded it to the bottom with a TIG machine. You can barely see the underside in one of the pics. I made a restrictor from a SS washer to sit on top of the flue to keep the flames from shooting out of the top. The lid has a flap that slides open to let the gasses out & to help keep the heat in when the burner is off. I hope this helps.....

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Junk, that's great! I've been recommending this for years, but I've never seen it actually done. I have an electric rig so not me.

Thanks!

BTW, did you ever assess whether the channel in the middle made a significant difference?

Well, the MLT was insulated the same way and had the same type of burner under it. If I put the same amount of water in each, the one with the flue got up to temperature faster but I never did any testing besides that.

It was one of those things where the materials were on hand & we were welding fittings on vessels and the guy doing the welding was in a good mood and had time that day! I sold it (it's still working fine) and am going electric.