I recently purchased a King Cooker outdoor propane cooker since I have started all grain brewing. It puts out a nice flame and I can bring 7 gallons of wort to boil in about 20 minutes. It has a nice blue flame at this point but then I have to turn it down to avoid boil over. In order to prevent boil over I have to turn the flame down until it is a yellow flame. The yellow flame causes lots of black soot on the brew kettle and is a real pain in the butt to handle the brew pot later.
Is this normal for an outdoor burner or do I have a defective burner?
Can you adjust the air flow via a damper/Venturi?
There should be an air intake adjustment on the front of the burner where the gas line goes in. See the attached picture.
There is an air adjustment valve but it doesn’t make enough difference to adjust the flame adequately. I even tried removing the screws that hold the valve on so I could turn it further. Nothing seems to help. Maybe I just have a defective burner.
Could be a bad hose regulator. Another thing to consider is if it’s a high pressure burner and the person you bought it from put a regular pressure burner regulator on it. I’m assuming it’s for propane and not natural gas right? CNG does not work on Propane and vice versa.
Here are a couple of observations on the propane tank and burner. I am using the exchange type of propane tank which states it is 15 lbs. The regulator on the burner says it is 5 lbs. I bought the burner at a home brew store so I assumed it was good for brewing.
I thought about buying a propane tank from a hardware store because they state they are 20lbs. Maybe I need a different regulator and hose.
Propane cylinders are the same weather they say 15 or 20. The max fill is 4.5gal (18lbs). Exchange is almost always 15lb. I have mine filled vs exchange. I have a spot down the street that can fill two tanks for the price of one exchange. That means I am getting about 37lbs of gas for the same price as 15 at the grocery store.
Are you adjusting the gas on the regulator or on the cylinder? Gate valves on gas cylinders should be opened all the way. A higher pressure regulator might help, but should be needed.
(I had to hunt this down I forget) Soot is caused by an improper mix of air and propane. If the burner is clean at full throttle, but sooty when you turn it down, then it is probably getting too much air. I bet you probably tried to open it MORE? You want the opposite. https://www.youtube.com/watch?v=7Ui3u7E1rBE I used an old school burner that caused soot for a long time but upgraded and have been soot free since!
I have a Blichmann burner but I would imagine that it runs on the same principal. I turn the gas down with the regulator and fine tune with the air damper. If the flame is yellow, there is not adequate air and you will need to increase the air flow. As you increase the gas flow via the regulator, it may be necessary to readjust the air damper. It took me a few batches to figure out how to reduce and increase the flame properly (without the flame being yellow).
Thanks everyone. I picked up a new regulator yesterday. I will see if that makes any difference. I have tried the suggestions above and none of them seem to help much.