Built a block arch, but can't get the back 2 pans to boil

[leppell]

Hey Gurus, need some help. I finally got my arch put together and took it for a test drive yesterday. The back 2 pans won't boil.....the third pan will kinda simmer, but that's it. Pan 2 boiled well, and pan 1 would slightly boil. I know part of the issue was the wood I was using (basically branch trimmings, I'm saving the good split wood for when it's go time). I didn't see any appreciable difference when I had the leaf blower idling in front of the door to get so AUF, other than blowing ash into my pans. I'm sure some insulation would help, but that's on the to-do for next season. Anyone have any other ideas?

Also, do you think making some redneck rope gasket out of aluminum foil to put around the pans would help keep the ash/heat from blowing out and hold up?
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[ecolbeck]

Nice looking setup! My first inclination is to ask how close your ramp is to the bottoms of the pans. The approximate rule of thumb is that the cross sectional areas of the space underneath the pans and the stack should be equal.

My next question is what diameter stack do you have? I'm guessing (based on the pictures) that it may be too narrow to get the kind of draw you want. This might also explain why the blower blew ash everywhere. The chimney draw was too weak.

[leppell]

...cross sectional areas of the space underneath the pans and the stack should be equal. .

I'm not quite what this means. But i can tell you that the patio block at the back of the arch is about 3.5" below the pan. Behind the last pan is open space until it hits the wall. Perhaps I need to ramp that up as well. Perhaps I need to seal off the void under the pans a bit better?

Also, the stack is 6", 5 ft tall from the boot. I'm probably going to add another 3-5 ft to it, after I trim a branch on the tree this thing is sitting by.

[ecolbeck]

I'm not quite what this means. But i can tell you that the patio block at the back of the arch is about 3.5" below the pan. Behind the last pan is open space until it hits the wall. Perhaps I need to ramp that up as well. Perhaps I need to seal off the void under the pans a bit better?

The area of the gap between the pans and the ramp should be equal to the area of the stack. Someone else will probably chime in and explain it better.

I would definitely make the ramp more substantial although simple materials can be used. When I made a block arch I just used small rocks for a ramp.

[Maple Lady]

Also, do you think making some redneck rope gasket out of aluminum foil to put around the pans would help keep the ash/heat from blowing out and hold up?
19596195971959819599

I've used aluminum foil as gasket before to get by with and it worked pretty good. You may have to replace it here and there, but it's cheap enough.

[maple flats]

For the area, you will do better if you do 4 things. 1. calculate the cross sectional are in the stack in sq. in. and then divide that by the open inside width between the side walls on the blocks. That answer will be the approximate distance you want between the fillers you have under the rear pans, maybe within 1/4-1/2". 2. The filler you have should so,me how be fixed so it forces all of the heat up, looking at the picture, quite a bit can go around, along the right side. 3. use something as a gasket for between the blocks and the pans, cold air can now get in along the sides and cool the pans. 4. have the width of the base stack be nearly as wide as the width between the 2 sides, now there is a partial dead spot where the heat does not get to the pans as well, because it is flowing towards the narrow base stack.
Also, maybe the stack should be a little larger diameter, what is that now? Think about that before you set the space under the pans towards the back.

[Wannabe]

I can't see the stack height but the easiest thing to try would be adding another section of stack for a better draw. Ash shouldn't be blowing in your pans.

[maple flats]

good point, the stack sould be at least 2x the length of the arch. If my eyes are seeing it correctly, the business length of your arch looks like 4', thus 8' minimum, but 10' might help more.

[leppell]

The stack is 6' diameter, 5' from the boot. I have another 5 to add to it, just need to trim off a branch to do it (couldn't find my pole saw).

I picked up a sheet of steel yesterday to close off the ramp and area under the pans a bit better. I'm also going to reconfigure the height a bit, get it a little closer to the pans. A bit of foil for gaskets, and I'm think it will cook a lot better. Trees should start thawing out again on Friday, and I've got a business trip Sun-Tues. Hope to be swimming in sap for a boil on Wednesday to see how it all works out.

Once I've got all the bugs worked out this season, I'll be investing in proper gasket material and insulation.

[retubjb]

Not a guru at all, but I have boiled on a block arch similar to yours for about 6 years. My 2 cents...if your fire is 8 inches behind the door, the front pan will have a hard time boiling as the heat is being pulled toward the back. A 6 inch stack is 36 sq inches so if your arch is 24 inches wide there should be only 1.5 inches of space below the pans. If your new sheet of steel will fit snug from side to side that will wok great. I didn't have that so for a filler I filled the voids with sand, it takes a little longer to warm up, but acts like a great heat sink once it is heated up. I even filled the side blocks to act as a heat sink for the blocks and that keeps them from cracking from the heat. The depth of liquid in the pans makes a HUGE difference in the boil and evaporation rate. Even though your pans are deep, your liquid will boil much better at only 1-2 inches deep even though you will get some scorching on the sides.

[Woody77]

The aria of a 6" stack is roughly 18" so your space should be closer to 3/4" under the pans. Make sure your space on the sides is the same too. My first year was a small block arch and I used a single flat pan with regular old fiberglass insulation as gasket material. it will melt if you burn hard but worked for me. As long as you have fun doing it don't swet the small things you'll get there

[ecolbeck]

For the record, cross sectional area of 6 inch stack:

A = pi x r squared
A = 3.14 x 3 Squared
A = 3.14 x 9
A = 28.3 square inches

[Altie22]

If you burn to hard does that gasket melt to the pan?

[leppell]

Well, the modifications *mostly* work. The sheet metal worked beautifully, but I didn't take into account the extra height added from my makeshift gaskets. However, now that I'm burning my good wood and have the rest of the stack in place, I think I may be able do do without the pan gaskets... Didn't have a wiff of smoke once the fire got hot. Thanks for the help everyone!

On the flip side, I filtered at 216, and forgot to filter again before bottling. Doh!
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[maple flats]

I hope your luck is good with bottles with caps like that. I had several seals fail a few years back and do not use any bottles with a cap like that anymore. Maybe store them in the refrigerator if you have room. I used to get maybe 10-15% seal failure, however that was at least 10 years ago, I hope the seal has been improved since then.

[leppell]

Thanks for the heads up on the bottles! I was already a little worried about them, since the cap is so shallow, though I think the shrink wrap will help. The bottles are probably going to mostly for giveaway to family/friends, and neighbors that allow me to tap their trees, while the bulk that I keep will be in Mason jars. Found a neat pour spout for jars to make them into proper syrup dispensers.