First boil - terrible draft, smoke, slow boil in flue pan

[tgormley358]

I’ve been working so crazy to get everything ready including new sugar shack, first time usin tubing, tanks, that I’ve had no one for a test boil. So last night was a frustrating maiden voyage on my new Lapierre Jr 2x5 raised flu evap, with 80 gallons o fresh sap. THe wisdom of test boiling was apparent, as I had trouble with draft right away. Flame and smoke partly going up the ramp and stack but also coming out the front doors, sides in between pans, and at the back where the stack starts at the top of the arch. I’ve used two other small evaporators use last two years, most recently a very similar design 19”x48” by Lapierre, with no such trouble. I’ve got 12’ of 8” stack, insulated with a flue opening knob, rain cap spark arrestor on top. Things I tried and got somewhat better results but still Smokey and minimal boil in the flue pan:

1. Made sure I had the flue open correctly since I can’t see inside the stack I pulled he 4’ actions apart And looked inside to make sure I was opening the flue corectly. Check.
2. Played with opening and closing the air door below th fire box door. No help.
3. Removed the rain cap figurung it might be limiting the draft. Maybe slight better slightly less smoke
4. Tried loading new old further to the back of the firebox up the ramp. Same smoke but the boil in he flue pan got worse. Hard boil in the syrup pan only which made sense because when I open doors the fire wants o jump out the front rather than go up to the stack as I’m used to with prior Evaps.

At this point I just hung in there openin all the doors and windows so I could breathe through th smoke and finish the boil 4.5 hours later. My wood is dry and seasoned just a hair under a year. It burned fine so I do’t think that’s it. Next chance I get I plan to look at the bricking under he pans to see if there’s any restriction there. I bricked it per Lapierres design and don t think I screwed that up. Only other thought I have is air flow from the outside. I have the evaporator front facing away from the predominant wind direction, opposite from what I’ve done out previous units. I did this for other reasons and didn’t think it would case a problem. Even with the doors and windows open it still smoked up so could this really be a problem?

I’m reaching out to Maple Guys where I bought It for help.

Tom

[maple flats]

A few things, first, do not use a damper in the stack unless it is oil fired and then it would be a barometric damper.
What size stack do you have? How tall is it? How far above the highest point within 10'? Is the wood split wrist size? Is it dry? How often did you add wood to the fire? How much did you add at a time?
There may be other questions, but those are for starters.
The stack should be a minimum of 2x the arch length. The stack should be whatever size the instructions say that came with the evaporator. The stack should go straight up thru the roof, it should be at least 3' above the roof and at least 2' higher than anything within 10 feet. With a shorter evaporator my guess is that besides having a damper which should not be, is that you don't have enough stack. It should be the longer of 2x the length, the roof height plus 3' or two feet above the highest point within 10' even if that is 3, 4 or more times the length of the evaporator. First, remove the damper, then tell us how the other criteria stated are in relation to what you have. Someplace you have a restriction that should not be. Do not use elbows in the stack, they are a big restriction to proper draft.
Also, are you on the leeward side of a line of trees or a hill with the wind coming over that obstruction?
With those answers the issue we can help you get it fixed.

[Big_Eddy]

+ Ditto Maple Flats.

Smoke always means not enough draft.

Get that damper out of there - no damper needed.
Make sure the smoke stack is as big as the thimble on the top of the evaporator. 8" seems small to me, but maybe for a 2'x5'
At the back of the flue pan - is there sufficient opening for the flames / smoke to come back down to enter the smoke stack, or is there a restriction there?
Add 6' to the top of the stack and see what happens. 12' is borderline IMO. I have more on my 20"x60".

The other thing to check - what was the weather last night? Damp and humid, with a wind can make even the best chimney not draw well, especially if your doors and windows are on the downwind end of the building.

[tgormley358]

Dave, i think most of what you’ve asked is in my original (long) post but I’ll include details here:

13’ of straight stack (no elbows) for 5’ evaporator. The top is 5’ above the roof peak, the nearest next tallest thing. My firewood is dry just under 1 year seasoned oak and hemlock. Could be dryer I suppose, I know some people say 2 years is bst. The damper came stock from Lapierre so I’ll have to see about removing it. Wonder why they put it on there.

I’m most interested in you comment about position vs leewad wind. I’m not sure I understand the definition of leeward so I’ll describe in my own terms. The shack is within 50’ of a hill and treeline. Wind comes up and over that hill toward he rear of my shack. The evaporator is positioned in the shack such that it’s crossways to the wind, but angled a bit more toward the direction of that wind. That prevailing wind would hit it pretty much broadside if the shack wasn’t there. In past years the wind came up over and hit the front doors of the firebox which gave great draft. This year the wind comes up over the hill, hits th shack, if it continued through the back door it would hit the evaporator at the stack end before hitting the front due to the slight angling of the stack end toward the wind. Is this what you mean by the leeward side.

I’m not feeling too good about this now having thought it thru. Tell me I haven’t screwed this up or hopefully there’s a way out of it without moving the evaporator and cutting a new whole hole in my roof.

[tgormley358]

Have to ask what’s the thimble? 8” was stock from Lapierre. Wouldn’t hey know what’s best with their own equipment? I don know. The stack is in 4 pieces, the starting at th arch, then a 1’ section which I think has the damper and connects to he next two 4’ sections of insulated stack. I think that 1’ section is meant to be a connector used if the stack were oing through a ceiling to another floor before the roof. Next step based on what you guys are sayin I should try removing that 1’ section which will get rid of the damper. If you guys are now sayin, why did he put in that section when it was meant for something other than my single floor shack design, I guess the laughs on me.

Appreciate you all helping out.

Tom

[tgormley358]

To be more specific with the wind, it comes over that hill from the NW toward SE. my stack is pointed NNE so the front doors are SSW.

[tgormley358]

Details on wood - it’s split thin but not all of its wrist thin. When it was real smoky las night I tried using Just wrist sized stuff and didn’t see a difference. I started with small loads and then went pretty full several inches below the syrup pan probably. Frequency was probably 15-20 minutes since the poor draft kept I from burning well.

Weather was damp. Maybe not the typical but I did feel that wind coming over the hill frequently. On the arch and bricking design, I bricked per Lapierre with one exception. The arch ramps up on angle from fire box; levels off for 13” within 1/4 a 1/2 “ of rails, then drops down the last 7” to the stack. Where it drops straight down by design, it calls for half brick laying flat, I had extra full bricks so I use them instead do th first row at the drop, but cut them to angle down to half brick height at the second row. So he initial drop from the top is probably 4” instead of 5” but then drops down to full 5” by the next row of brick.

[Biz]

My Smokey Lake 2x5 (new this year) has a 7" stack, I had it special ordered to fit my existing roof jack. Standard stack is 8" Stack is about 12 ft. I thought I was going to need to add a length but it is working fine as-is, no issue with draw. This is what is working for me.

Dave

[Haynes Forest Products]

Do you have your fire blanket or brick up to tight to the flues. There is a transition at the end of the arch where the gases have to go down under the bulkhead of the pan to get out.

I got to tell ya I have guys firing 5x12 2x6 3x10 and they don't cut the wood up small to wrist size. If you have a good fire and dry wood to feed it we jammed it full of anything and any size and once you have a good draw it will burn. Something is restricting it. Does the flue stack come out the top of the back of the arch or the back with.a 90 degree fitting.

[tgormley358]

Yes I do. When I finished bricking I checked it appeared o be 1/4 a 1/2 “ o op of rails. Then it drops off for the last 7” to the stack as you describe.

One place smoke was comin out surprised me, where the Very bottom of stack sits on the arch. That tells me it just doesn’t want to go up and out of the stack for some reason. Most likely it’s the damper in the stack provided by Lapierre by I probably shouldn’t have used it.

[lords sugaring]

4.5 hours to take down 80 gallons ... wow that's not good. Hopefully you get that thing tuned up and roaring to full potential. Curious how many gallons it took to fill the pan up ?

[mellondome]

I would say your biggest issue is the location of your shack.. and damp air. Adding forced draft ( air under fire ) . With the conditions you were relaying, you are getting a supressing draft down the stack.

As others have stated..ditch the damper and the stack cap.

And from previous experience.... it does make a difference whick way your rig faces, especially if it is natural draft and your shack is open / drafty.

Fing a squirle cage blower that fits your ash door and crank it up.

How open are you running your draft door?
And check to make sure there is nothing blocking your stack... ( nest, critter that got stuck, ...)

[tgormley358]

Guys (and gals), I checked down the stack tonite and found the damper partly closed. More closed than open. Problem solved. She’s boiling like she’s meant to. I’m a happy camper. Thanks for indulging my naievete.

[RileySugarbush]

I'm glad you found the problem and are on the right road. I'd take that damper out of there. I can't think of any good use of closing down the stack. It can only cause trouble.

[Haynes Forest Products]

Better it was the dampener than a 1/2 cooked Raccoon.:o