NG Burner Question

I am testing out my new brewery. I have been having issues with the burners not burning cleanly. After having to wait for pressure to build or my BK, it finely lit and was burning cleanly for about an hour with nice blue flames and the heat shield was glowing red. I turned it down to do some work underneath the stand, and when I turned it back up it was burning yellow. I could not get it to go back to the nice blue flames again. My HLT was burning yellow as well earlier. I am thinking about plugging some of the burner tips (https://www.homebrewtalk.com/f11/taming-wild-beast-multi-jet-burner-mod-52154/) but I am perplexed as to why it was working great until I turned it down.

Crickets

The multi jet burners are at best wide open/off control, when the gas flow is reduced the burner tips can not pull enough air to burn clean and you end up with yellow flames,lots of soot, and carbon monoxide from incomplete combustion. A second problem you probably have is the hot gasses trapped under the keg or pot get pulled down into the burner at lower flow levels. If you are looking for clean burning at all settings then the multi jet is not the one for that, the 10" SQ-14 is the best suited for adjustability. A fix to improve the trapped hot gas problem is to cut vents in the keg skirt, this will help but not cure the yellow flame problem.

How do you think I got it to burn clean for 40 minutes before I futzed with it? What was odd was that a minute earlier I couldn't even light it. I am guessing my forced air furnace and radiant heat boiler were both running at the same time.

BTW: Do you think plugging some of the holes would help so I can run it closer to full open? Right now full open would burn down the house.

Plugging the jets to reduce the number to around 10 - 12 would be a big help, but the fewer the jets you have the greater the importance of which way they face. When the tip count is reduced they need to point at each other to be able to transfer the flame for ignition, there are a couple examples in older threads of how this was done. The better long term idea would be to sell those burners to some one building a 1bbl system with 55 gallon drums for kettles, and change to the 10" cast burners.
When the burners were originally fired they created enough draft to keep the fire clean, when you throttled them down that was lost and combustion gas feed back did not help when you throttled up again.

joety said:

How do you think I got it to burn clean for 40 minutes before I futzed with it? What was odd was that a minute earlier I couldn't even light it. I am guessing my forced air furnace and radiant heat boiler were both running at the same time.

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I think you nailed it here depending on how your gas lines are piped. If I was to run my brew stand while the heater, water heater, fireplace & gas range were running I'd be in trouble. If you were tee'd off the main line from the meter you would be better off. btw - I just upgraded my flex line to 1/2" from 3/8" and it makes a world of difference to the final output.

Same problem here. I ended up plugging a bunch of holes with some good results but still have the yellow flame issue. I also read somewhere that a low pressure regulator can help. I am looking into that now.

HoppyGus said:

Same problem here. I ended up plugging a bunch of holes with some good results but still have the yellow flame issue. I also read somewhere that a low pressure regulator can help. I am looking into that now.

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Interesting, please let me know what you find.

Anyway I can create that updraft again?

I've given up trying to make the multi-jet burner work. I just ordered the Hurricane burner with the Natural gas conversion valve so hopefully I can hook this up and be done with it.
I will use the jet burner in the fire pit outside in some way.

I have one of these and I'll share a few items I've discovered. It is imperative that all parts from your gas main to the burner are sized appropriately to the BTU rating of the appliance. If you look at the packaging for one of those flex connectors, you'll notice that they are all not the same. Different sizes have different maximums for allowable BTU. In my setup, I have all 1/2" black iron pipe directly from the main NG trunk in my basement. Between the terminus of the black iron feed line I have a 48" flex connector whose max BTU rating is 106k (higher than burner rating). On the stand, again, I have all 1/2" black iron piping. Valves are simple 1/2" standard NG shutoff ball valves. I use 3; 1 at the main trunk connection, 1 before the flex, and 1 just before the burner used for burner control. Another key item is the installation of a "dip-tube" near the appliance. Look around at your other NG equipment in your basement and you'll see what I'm talking about; it's the 6" piece of pipe that drops down and is terminated with a cap. I don't know the purpose of these but from a gas technician I was informed about the necessity of this.

I don't have any of the jets plugged and am able to control the burner flame nicely with the valve approximately 1/4 open; no yellow/orange. I think the bulk of issues experienced with these burners result from improperly sized components being utilized with them and/or too much being asked of a single feed line. In my opinion, each burner would require it's own dedicated 1/2" feed from the main trunk or maybe a larger feed. But, I'm pretty sure that it becomes impossible for your NG service to keep up with the demand placed on it by two 100k BTU appliances.

My $.02.

One more thing. On one or two occasions, mine started burning un-cleanly; I simply put my face down there and blew into the burner and it righted the problem.

bryanshults said:

One more thing. On one or two occasions, mine started burning un-cleanly; I simply put my face down there and blew into the burner and it righted the problem.

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Interesting, I had that problem last weekend with maybe two of the jets. Left a small black mark on the bottom of the kettle that washed off.

I've been running pretty well since I posted this. I do have issues sometimes initially with getting pressure, but once she goes as long as I don't throttle it way down I'm fine. I do need to look into the dip tube. I don't have one and as you've said the other appliances do.

As far as supply, I have a 1" pipe that comes right off the main 1" trunk and drops down to 1/2" right before the flex connector. I think I have a five footer, vs your four footer, so it's a tad less in BTU's, maybe 96,000.

I think I'll be OK after all.

bryanshults said:

Another key item is the installation of a "dip-tube" near the appliance. Look around at your other NG equipment in your basement and you'll see what I'm talking about; it's the 6" piece of pipe that drops down and is terminated with a cap. I don't know the purpose of these but from a gas technician I was informed about the necessity of this.

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Drip leg ! for allowing sediment, moisture, etc. to fall out of the flow of the gas.

I experience the same thing as the OP with the same burners. You can get them all to light and burn blue at first. If you turn the flame down to the point where it goes orange/yellow, it quickly builds up a pillow of CO under the keg skirt and even if you turn the flame up, it burns badly. A quick puff of air across the burner, a bit upwards into the recess of the keg clears this gas out and lets it burn better again. This problem is likely made worse the closer you mount the burner to the keg. Look at the burner, the air intakes are about two inches away from where the flame is and they need to be pulling oxygen rich air into them, not CO.

Also note that if you run dirty for too long and actually get carbon coating on the keg, it will produce more CO while heat is applied and even if you clear out this offending pillow of gas, it may build up again after a few minutes. In that case, I agree with Kladue and adding more venting to the skirt would help.

Bobby_M said:

I experience the same thing as the OP with the same burners. You can get them all to light and burn blue at first. If you turn the flame down to the point where it goes orange/yellow, it quickly builds up a pillow of CO under the keg skirt and even if you turn the flame up, it burns badly. A quick puff of air across the burner, a bit upwards into the recess of the keg clears this gas out and lets it burn better again. This problem is likely made worse the closer you mount the burner to the keg. Look at the burner, the air intakes are about two inches away from where the flame is and they need to be pulling oxygen rich air into them, not CO.

Also note that if you run dirty for too long and actually get carbon coating on the keg, it will produce more CO while heat is applied and even if you clear out this offending pillow of gas, it may build up again after a few minutes. In that case, I agree with Kladue and adding more venting to the skirt would help.

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Very, very helpful, Bobby and explains my issues to the "T". I should be good to go from here. FWIW, I'm glad I kept the original jet burners if nothing else for the cool factor.

Used my Hurricane burner yesterday and I am not even thinking about looking back to the multi jet burner. Even flame, no soot, quick and steady boil. This burner allows me to get even more drunk while brewing! Yeah!

HoppyGus said:

Used my Hurricane burner yesterday and I am not even thinking about looking back to the multi jet burner. Even flame, no soot, quick and steady boil. This burner allows me to get even more drunk while brewing! Yeah!

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Be careful, I have a scar on my arm (steam burn) and my fingers are still healing from two weeks ago when I grabbed the wrong side of a kettle. Alcohol may have been a factor in both incidences.

joety said:

Be careful, I have a scar on my arm (steam burn) and my fingers are still healing from two weeks ago when I grabbed the wrong side of a kettle. Alcohol may have been a factor in both incidences.

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I have many burns from the hot skirt of the keggle hitting my leg, Sparge water leak and thought it was a good idea to grab the hose and put it back on not realizing that the whole top of my hand was burning and just the other day welding my new stand with out gloves on. It looks like I have weird looking freckles on both hands now! :cross:
I'm a glutton for punishment I guess.