Thinking about building a camp stove type natural gas setup...questions inside

[jdircksen]

I have been thinking about using natural gas instead of propane because it is cheaper for me and I can tap into the gas supply in my house. What I'm thinking of building is essentially a camp stove with 4 burners from old water heaters. I plan to use 2 or 4 full size steam table pans.

Where did this idea come from? Currently I am able to get a mild boil on my electric stovetop with a full size steam pan. The stove uses 2 burners + a bridge for a total of 4400 watts. The internet told me this is equivalent to 15,000 Btu. Keep in mind this is across 3 burners, which are spaced pretty evenly across the pan.

Questions:
--Given that a steam pan is about 21"x12", would a single burner, say 20,000 Btu be sufficient to boil it?
--Would it better to have one steam pan across 2 burners -- or -- 4 steam pans with 1 burner each? Perhaps start the pan across 2 burners but move it to 1 burner if it can maintain the boil.
--Should I use smaller steam table pans instead of the full size ones?

Here is a drawing of the options I've come up with.
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And here is SDdave's setup that I came across. It's a fancier version of what I came up with.
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[jdircksen]

added pictures to help visualize what I have floating around in my head

[littleTapper]

Go double burners...and then maybe just get a larger pan to fit over all them vs individual steam pans. I was contemplating something like this a few years ago, but then I just went and built a wood-fired arch to fit a 2x4 pan.

[jdircksen]

Thanks for the reply. I like your idea. Maybe I'll do the 3x2 burner setup and build the stand in a way that will fit a 2'x2' pan later. I could use the other burners to preheat and finish.

[maple flats]

If you make it to heat the entire arch area, why not make a tube burner design. For that you just need to know what size holes to drill along the length of a black pipe and a gas valve at the inlet end of each tube. This is how the medium and larger finish pans are made. My finisher has holes about every 3/8 or half inch. You may want to weld a cap on the dead end or weld a flat steel plate rather than using any means to seal a screw on cap. I can't help on hole size, my finisher is propane and those 2 operate at much different pressures. The other option for a tube burner might be to plumb in an orifice at the inlet end of each tube, then the hole sizes would not be critical, they could be larger.
A tube burner disign would give you much more uniform heat.

[jdircksen]

That's an idea I hadn't considered. I don't know much about gas tube burners but I know they are used for grills. I know you can put a heat deflector above the pipe to spread out the heat, but I'm not educated enough to know if I'll need 1 burner or more. I'll see if I can find any threads on here about building a setup with tube burners.

[maple flats]

My 2x6 finisher has 4 tubes, but I have a hard time getting the flames low enough to get a medium hard boil burning 4 so most often I run 2. Mine have no flame spreader but the boil even with just the center 2 tubes burning is over the entire surface.
It seems an evaporator would do the same. My finisher is 2' wide with one divider, you may want 4 sections on an evaporator to get a longer path.

[jdircksen]

Ok so my plan is still evolving. I found out some family members made syrup many years ago, so I'm borrowing some pieces from their setup. There are 3 burners and a 2'x3' pan. The pan is heavy steel, I'm not sure if it's stainless but it is pretty evenly blackened. I can see that at one time the pan had 6 burners under it.

I'm thinking of building an oven with a single row of cinder blocks (with one end open), like some people do with wood fired evaporators. Since cinder blocks are 8" tall, and the burners are 5" tall, there would be about 3" between the burners and the bottom of the pan. I'll have to test and see if the 3 burners produce enough heat to boil the sap. I'll use black pipe to get out of the oven before I connect to rubber gas hose. The problem is see with this is that the adjustment knobs would be in the oven, so I'd have to use the gas shutoff to regulate the flames.

Anyone have thoughts on this setup?

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[SDdave]

Should work alright. There is a couple of items I would address. One is to put a regulator on the tank and use that to control your burners. The second is aesthetic, make sure you are not boiling over a prized section of lawn. I did this a few years back, not only did it take the frost out of the ground but it killed the grass. Had to hear about it for years...

I can't speak on the pan itself, but it should evaporate.

Have fun!!

SDdave

[jdircksen]

Edit: After more research, I think it is risky to have the cement in contact with the high temperature of the oven-like setting. I'd rather elevate the burners off the ground, then put the pan on top of it (like SDdave's picture in the first post of this thread).

I'm hoping to work inside a 3-sided screened in porch that has a concrete floor (probably 8-12" thick). I'll probably put 1/4" cement board underneath to help protect the floor.

I know concrete is fire resistant but I don't know if it can stand up to heat for several hours at a time. https://home.howstuffworks.com/home-improvement/construction/materials/concrete-fire-resistant.htm

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