Raised flue arch question And draft

[1951oliver88]

It's our first year with a raised flue small brothers lightning. We had 10 feet of stack and built our first fire at first we had smoke coming out of everywhere in between the pans in front of the front pan the sides of the flue pan. We added another 6 feet of stack. This helped but fire was still lazy had small dry wood draft door wide open. From my experience with wood stoves you shouldn't get smoke out the door like we had at first and with as much pipe as we had up the fire should be roaring especially with doors open. The arch is filled with sand almost to the top
Of the rail under the flue pan to force the gases up through the flues. My question is should the sand be dug down a little in the back where it goes under the plate and then up the stack. This I think would create more draft. The people before us way have had it set up wrong.

[northwoods_forestry]

How big is the arch? If it is 8' or less 16' of pipe shouls give you plenty of draft as long as you are clearing the roof and other nearby obstructions by at least 2 feet.

If your arch is the same as mine there should be 2 partitions that extend up to the rails. The firebox should be bricked at a slope up to the first partition, forcing the fire into the flues of the sap pan. The space between the first and second partition should be filled up to the rails with sand or vermiculite. After the second partition it should be insulated and bricked at a slope down to the chimney opening, though should also work ok without a slope.

[1951oliver88]

Everything you said makes sense to me except the second slope back down to the chimney. If I use sand I can still slope it a bit? It is not sloped at all back to the chimney. Arch is 6 feet long

[northwoods_forestry]

The slope back to the chimney isn't critical for the draft, though it may have a bearing on how well the back of your pan boils (someone more knowledgeable than I will need to answer that). I just wanted to be sure you are leaving enough room back there to allow everything to go up the chimney.

[Flat47]

Before I added arch rail gasket, the same thing would happen when I first got going for the day. After a little while, the fire would get going better and the pans and stack would begin to heat up it all straightened out. Even now with the rail gasket, when I start my fire the draft is a little "lazy." But once things heat up it's all good.

[Brent]

How about air supply in the sugar shack. If it is well sealed you could be choking off air. It has to flow in freely before it can go out freely up the stack.

Do you have the ash cleanout door open? It needs to be open to let air in.

Is the grate covered with ashes, choking off the air supply ?

Normally on a smaller rasied flue rig the filler will pile up to only about 1/4" below the bottom of the flues. An 8 to 10" gap at the front to let the flames / hot air up between the flues and maybe about 3 - 4" at the back to let it back down into the chamber below the stack. This is how we set up our 2' x 6' raised flue. I personally don't like the idea of sand. It's very heavy. It holds moisture that can rust your frame. It holds heat for much too long after you shut down at night. When you're done boiling you want the chill / refrigerate the sap to stock microbes and bacteria from multiplying. You can end up with ropy sap and syrup and have to dump the whole mess and waste a day cleaning out your rig in the middle of the season. I very much prefer vermiculite. It's cheap. It's light, It's an insulator. It won't hold heat. We covered it with green archboard but that might not have been needed. We put in a row of bricks to make a wall to create the gap back near the stack.

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[1951oliver88]

My sugar house is an old garage plenty of air leaks! Ash door wide open fire didn't even take off when fire doors are wide open. I just took the pan off and dug the sand out from under chimney it was quite full I dug out about 4 inches from the back of the pan towards the front. To me it makes sense to give the gasses ample space to get back out of the flue pan and up the chimney. The people before me admitted that they would have to run a blower to get it going good. I am hoping that taking some of the sand out helps. Sand was in it when we bought it froze in actually (moved it that way super heavy) may look into the vermiculite after this season

[stewardsdairy]

We used some fire brick in the back of the arch to keep sand level stable. By playing with the amount of sand in the back you can change the draft. If you need assistance some evening this week I am pretty close to you and am going nuts waiting for my new rig. Send me a message and I'll give you a phone number.

[miller maple]

i have a raised flue new to me this year and when i was bricking the arch i called leader and a couple other places to get some insite about the best way to do it and this is what i did and is seaming to be working well. under the flue pan i put a layer of fire brick, then i put a couple inches of sand then i filled it up to the rails with vermiculite and on the back side i started my slope down to the chimny at 6 inches from the smoke stack, and ontop of my vermiculite i sprinkled some dry concrete dust then sprayed it with a mist of water so it got a thin hard crust on top of the vermiculite, because the vermiculite is very lite. and will get sucked right out the stack if not healed in place by something, just an idea it worked for me good luck.

[nwoods57]

I'm new to this and could any of you guys put some pics on here , I'm looking to building an arch and don't quite understand the concept of the design.

[miller maple]

5439 this is my arch

[1951oliver88]

Thank you for all the replies. I took some sand out of the back and it draws like crazy now. We boiled for 7 hours yesterday.