Arch Slope Advice Needed

[SeanD]

I have two flat three-foot pans.

Last year it was hard to keep my back pan boiling so I brought the bricks under the back pan up closer to the bottom of the pan. After the initial ramp out of the firebox, I had the bricks run level under the back pan with a slightly higher raised dam just before the stack. I've been having pretty poor boils this season - worse than last year, so I don't think the way I reworked the arch in the off season did any good.

My front pan has been boiling well, but the back pan has been stubborn - not even boiling at all when the front pan is. Stack temps are way down too. For some reason it won't really boil unless I stir the heck out of the coals in the firebox before I throw the new wood in. Then it will rip and roar for a few minutes, but then die down pretty quickly. The draft seems good. It all pulls toward the back when I open the door.

So I reworked the brick to have a more gradual slope on the way to the back. I left the last 16" or so before the stack up 2.5" inches below the pan and the dam just before the stack is 2" below the pans.

The first picture shows how I had it set up before tonight and the second picture shows the new slope I put on it. I'll find out how it goes when I boil in a few days, but I'm open to suggestions while the pans are off. Should I slope it further back? Lower the dam? Any ideas are welcome.


53775378

Thanks,
Sean

[RileySugarbush]

Seems to me you don't have enough draft.

[Ausable]

You answered your own question and so did John. You have plenty of air for combustion - when the door is open and it burns just fine and when you close the door the fire dies down. Sounds almost like a wood stove for heating a home. Do You have an ash clean out door on your arch? Thats what I use for additional air on mine and it works just fine. Sean - I can tell by the pictures You have a nice rig - the key picture would have been of the front where you toss in the wood to see if it is getting enough combustion air. Your pictures look like everything is air tight as on a forced draft arch setup. You don't mention a forced draft blower so I assume you have natural air circulation.........Need more air. Should be an easy fix.....best of luck---Mike--

[SeanD]

I wish I could take credit for the arch. This is Bill Mason's work.

I just use natural draft through the ash door and I leave it wide open. On my old block arch when I didn't have a good enough draft, I had a ton of black soot built up in the stack end of the arch. Since these bricks were clean, I figured I was good. Maybe not?

It's an 18', 8" stack on a 2x6, so I'm hoping to maximize the natural draft, first. Do you think I should take that air dam at the end down?

Next on the list is sticking a small fan in the ash door temporarily. The leaf blower experiment ended up being a bit too much.:o

Thanks for the help,

Sean

[RileySugarbush]

That is plenty of stack! Next I'd look at your grates and wood. If anything I'd close the gap a bit more.

[B.D.L]

the way you have it set up now looks just like mine,i had the same trouble your having before i lowered my ramp and made wider spacing between my grates so that the coals stopped restricting my draft, i wouldn't go any closer to the pan, because you may choke it off to much.

[Brent]

without seeing the whole picture, it's hard to tell but
- I'd lower the 2" dam at the back
- I really suspect the grates are not letting enough air through, possibly getting chocked with ash
bigger holes or bigger gaps
- get a simple fan and sit it up to blow in the ash cleanout door, if that gets the flame going better then
maybe you need to work up a real blower. We put a simple fan like that on our Leader Half Pint and it helped
quite a bit.
- if none of the above helps much, I'd be suspicious of the wood still having too much moisture in it.

[RileySugarbush]

Agreed. Air flow through the grates if probably the problem. I have never run an arch without a blower, so I'm no expert on that, but it is critical that the grates never clog up with coals/ash.

[Flat Lander Sugaring]

my 2x6 has a 7" stack 15', with three blowers. I should actually move to a 10" because of blowers. before I had the blowers I could get a blow torch out top of stack with natural draft. Now with the 3 blowers NORAD sends jets over to see wth is going on :lol:. sounds like you need more air.

raised flue? if it is build a couple ramps a foot or two apart to keep the flame shooting back up into the flues.
Drop flue? get the bottom of the arch tight to the flue with sand, vermiculite(sp) arch blanket or something.

[SeanD]

Thanks for all the feedback.

The grate could definitely be the problem or part of it. It seems when I really kicked up the burned up hunks of wood right down to the grate, that's when it would start to roar. Of course, I had the door open at the same time so all kinds of air was shooting in. I have four sections of grate evenly spaced, so if I want more space, I will have to take one out and spread the three out. If that ends up being the solution, that couldn't be any easier.

I'm burning almost all pine for the first time. Usually I have a mix. Some of the early stuff was a little damp because it was the last to come inside, but I'm into the dry stuff now.

I'm undecided about the dam. The scientific method side of me is trying to limit variables/changes to pinpoint the problem. Last year I thought my lackluster boil in the back pan was because the heat was racing past the pan and up the stack. That's when I was getting a nice looking torch coming out of the top of the stack. If nothing changes in the next boil, I can take the dam out pretty easily the next time I clean the pans.

I borrowed a small fan from someone. I'm definitely going to try that no matter what I do with the dam or grates. I know it won't hurt. If it works, then it was a pretty easy fix.

I'll let you all know how it goes and try to include pics.

Thanks Traders!

Sean

[Flat Lander Sugaring]

Thanks for all the feedback.

The grate could definitely be the problem or part of it. It seems when I really kicked up the burned up hunks of wood right down to the grate, that's when it would start to roar. Of course, I had the door open at the same time so all kinds of air was shooting in. I have four sections of grate evenly spaced, so if I want more space, I will have to take one out and spread the three out. If that ends up being the solution, that couldn't be any easier.

I'm burning almost all pine for the first time. Usually I have a mix. Some of the early stuff was a little damp because it was the last to come inside, but I'm into the dry stuff now.

I'm undecided about the dam. The scientific method side of me is trying to limit variables/changes to pinpoint the problem. Last year I thought my lackluster boil in the back pan was because the heat was racing past the pan and up the stack. That's when I was getting a nice looking torch coming out of the top of the stack. If nothing changes in the next boil, I can take the dam out pretty easily the next time I clean the pans.

I borrowed a small fan from someone. I'm definitely going to try that no matter what I do with the dam or grates. I know it won't hurt. If it works, then it was a pretty easy fix.

I'll let you all know how it goes and try to include pics.

Thanks Traders!

Sean

the torch is neat but loosing heat out the stack< i didnt say it was efficient. if you build a upside down wall from the top down a little, heat doesnt like going down so it will bounce back into flue area. but how ever much you build the wall down you have to drop the bottom of arch the same so you dont loose the draft thing you were talking about

[SeanD]

I finally had enough sap to boil and the modification to the slope made a huge difference. Right away, things sounded better. I got a rumbling sound when I shut the door after firing. I got a boil in all four sections of the front pan in 30 minutes and the second section of the back pan was going in an hour. I didn't write down when, but I got the first section of the back pan boiling a little while after that and was able to keep it up most of the day.

My rate for the first two boils was 10-12 gph. Today I got almost 16 gph and I had peak runs when I was almost getting 20.

I did hit a lull at one point, though. Seems like I always do in a boil. Just when things are ripping suddenly it will just start to die. I think it has more to do with my wood and firings. I may pull one of the grates out for the next boil. I tried the 10" fan in the ash door during the lull and honestly, nothing happened. How high should I run it and how quickly should I see a difference?

There's a thin crack between the back pan and the stack where I could see consistent ribbons of orange. Usually, I just see orange sparks fly by. So the flame was licking toward the very back of the pan when things were going well.

Thanks for all the input.

Sean

[SeanD]

The four grates I have leave an inch gap between them. I took one of the grates out and it leaves about 1.75" between them now. Looks good for air, but it seems like large coals are going to be falling into the ash pit. Is this too big of a gap? The ash pit itself is uninsulated. What do you think?

54625463

Sean

[Brent]

I think the one inch you had was OK. From memory the gaps on our 2 x 6 were less than an inch
The floor of the ash pit on Phaneufs is not .... I mean there is none. I put cement board underneath and
put fire brick on the sides. In hindsight I'm not so sure the bricks did anything useful down there.