Better GPH Without Door

[Manatawny]

I boiled on Saturday in my new, 6 steam pan block arch. I used blocks as the door, too (handling them with welding gloves). I left the bottom row oriented outward, to allow air to enter there. When I realized that that wasn't enough air, I left a gap in the middle row, and that helped. But I noticed that whenever I removed the door altogether, it really took off.

So, I boiled about 8 hours with the door on, and averaged 3.5 gph (ugg). Then I boiled the last 2 hours without the door, and I got about 7gph for those two hours!

With the door on, pan 2 and pan 3 boiled... the others steamed but didn't boil (pan 1 and pans 4-6).

Without the door on, the first four pans boils (pans 5 and 6 still did not boil).

So, why does everybody say to "hold heat in" with a door? What is wrong with my set up that I am 2x as successful without a door?

Also, is it normal that I can't get pans 5 and 6 to boil? Am I being barely more efficient than a 4 pan arch?

[psparr]

Well you found out you don't have enough air, that's a good thing.
Do you have a grate for your firebox?

Also how close to the pans is it at the back of the arch?
A couple pictures would help diagnose things.

[barnbc76]

I used to have the same problem. It is difficult when you have a firebox the entire length of you pans. On my fuel tank arch it is only 2' where as it was closer to 3' on the block arch. You need to find a way to put a grate under it you will be surprised. I used pallet wood which burned hot and fast but the thicker wood created too many coals. My new fuel tank arch burns more efficient so it does not leave tons of coals.

[Manatawny]

By grate, you just mean a fireplace grate, right? As you can see, I have that:

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Immediately after the grate--about halfway into pan #2--a ramp begins:

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That ramp then levels out to a plateau, about halfway into pan #4. It is then flat to where it meets an 8x8 opening to my 8" stack:

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That plateau is 5" under the bottom of my (4" deep) pans.

I'm fine just burning without a door. Is the 7gph I then get about what I should expect from 6 steam pans? Or should I be getting better?

[psparr]

You can figure 1gallon per hr. per sq ft. of surface area. You should only have an inch or two at the most under the back pans. Will keep your heat up under the pans.

[maple flats]

Yes, you have too much space under the pans. The area after the ramp where it is flat, what is the space from the flat to the bottom of the pans? It should be 1 1/2-2" max. To calculate the space, with an 8" stack you have just over 50 sq. inches of area, so you want the space very slightly less than 50 sq. " under the pans past the top of the ramp. How high is your stack? Then can you find a safe way to cover the front with a full 8x16 space at the bottom, under the grate, that is about how much air you want entering. The stack should be 2X or slightly more as high as the overall length of the pan length as it is set up.

[Manatawny]

Aha! That makes sense. The cubic area under my back pans should be equivalent to the cubic area in my stack, which when spread over 20 inches means not much space.

Easy improvement.

Now, here's my question, though: this will mean that the flame will have to dip back down at the back (somewhat...partly...) to enter the stack. Is that OK?

[psparr]

Perfectly acceptable.

[psparr]

Give me some the dimensions of the firebox area and I might bring you a present.

[maple flats]

My factory evaporator has a drop of about 8" where it meets the bottom of the bast stack. That is good, not bad.

[Manatawny]

Ok, I raised my ramp and put some ceramic tile there (a cheap attempt to retain the dirt, and not have it sucked away):

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I left 1 1/2" under the pans. Here's a pic with just one pan on, to show you (it was almost dark...hard to see):

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I'm looking forward to seeing how this works, on Saturday!

Psparr, to answer your question:
At the front, my walls are about 22 3/4" high. From inside to inside, the width is about 19 3/4". The length of the pans comes to about 77".

I plan to start evaporating around sun-up, on Saturday. I'm at 103 Berks St., Pottstown. Feel free to swing by in the morning!

[eustis22]

Wait. Coals are BAD? Why?

[psparr]

Will do!

Eustis coals can't get as hot as a flame, and it restricts the airflow up through the wood.