Best lining for a gas fired arch?

[jdircksen]

I'm building a stand so I can mount natural gas burners to boil sap in steam table pans. The burners will be 2" from the bottom of the pans and I plan to wrap the stand with tin so it covers 12" down all 4 sides. That should help block the wind from blowing out the flame.

Do I need to line the inside with anything --- fire brick, ceramic blanket, maybe even cement tile backerboard? I'm not exactly sure what the purpose of fire brick is, but if my fire is directly on the bottom of the pan do I even need any lining?

[maple flats]

Ceramic blanket is normally used. Study before you finish the build, I've had 2 finishers, the first was just 16x34" with 2 burners, I think the burners were 6" below the pans. My current finisher has tube burners, they are 8" below the pans. By the way, tube burners work way better. They can be made by drilling gas ports in a black iron pipe. I can get a diameter for propane if you like, just PM me. Then you would need to get the gas valves for each tube with the air inlet adjuster. The main difference, the 2 burner type burned a ring on the bottom right where the flame hit, just like it did back when I had a propane fired bottler. A tube burner spreads the heat better and can do the job easier.

[DRoseum]

I would use firebrick. It worked great for my set up. I wrapped everything in galvanized ductwork. Go further down than 12 inches though, the wind can still be problematic. I plan to extend my wind shielding another 9 inches.

I agree about pipe burners. You can get very reasonable stainless steel u shaped pipe burners. That is what I used and they worked great. Added air/gas mixers to get pure blue burn to increase heat and efficiency and cut down on soot. Also probably want the burners a bit lower. Want the tips just touching the pan. Make sure you plan for a vent stack and damper.

https://www.sugartree.run/2019/03/custom-hobby-maple-syrup-evaporator.html

[maple flats]

My 2x6 propane finisher has a 6" stack, no damper. It heats very well.

[jdircksen]

Thanks for the info. This is going to be a bit of trial and error. I am planning on the 2" space between burners and pans because that is the gap on my water heater (that's where I'm getting burners from). As far as I can tell, there is no air venturi on a water heater, so I'm going to match the gas supply to what you'd find on a residential water heater and hope for a nice blue flame. If it doesn't work out then I'll probably head towards the pipe burners, though I was hoping to hold off a few years. I like the idea of customizing the boil size based on how much sap I collect. The way I'm picturing pipe burners will be best for a 2x3 pan.

I do have small gaps at the rounded corners of the pans for heat to escape. I've been looking at several gas setups including DRoseum's, but I haven't seen a vent stack on any of them. Wouldn't a vent allow the heat to escape?
20167

[DRoseum]

It's on the back end and not a good picture of it. It's more about letting the combustion exhaust gasses escape and not the heat. Just like the vent stack on top of water heater.

You will need a fairly large supply line to really run 6 burners. I ran 1 inch and it worked well. There are pipe size calculators online that can help bases on desired BTUs and length of the supply pipe run.

https://www.engineeringtoolbox.com/natural-gas-pipe-sizing-d_826.html

[jdircksen]

Ok great, good call. I’ll incorporate a vent once I add the sides.
I will have a plumber help me once I start building the gas lines. My plan now is to connect to the 1” ID supply with a 3/4” hose into a 3/4” manifold. From there I’ll have 1/2” valves feeding each burner.

[DRoseum]

That sounds like it will work. I did 1" supply and manifold down to 1/2" valves as well.