vermiculite and evaporator

[lastwoodsman]

I have read that when adding vermiculite inside the evaporator to close the distance between the heat and the pan. Some folks sprinkle mortar mix or portland over it and water it lightly. Also I have heard that the ash itself will hold it in place, without out it blowing out. (All good ideas)
What about cutting cement board to fit and lay it over the top of the vermiculite? I would think that would make a great topping to the cake. It would not burn off and would hold the vermiculite secure.
Any thoughts?

20 inches of snow in the woods so far. Time to start breaking trails with the tractor for spring.
Counter tops and sink in --only need to install stack--gettin close--see photos.
Woodsman

[C.Wilcox]

Woodsman,

The cement board will crumble into bits after the first few firings, but it shouldn't matter if you're just using it to hold down the vermiculite.

[ejmaple]

i used vermic with splits on top.

[MartinP]

I use cement board over and it looks fine after 1 year of use.
If you don't cover it it willsnow vermiculite when you are running.

[Haynes Forest Products]

Are you using the Asbestos free vermiculite?

[lastwoodsman]

That is a good question-- I bought it at work--a nursery, we use it in plant mixes and is from a nursery supply wholesaler--I will check but I am reasonably sure it is free.

Woodsman

[Father & Son]

I bought a bag of play sand at Home Depot and put about a 1" layer on top to hold the vermiculite down. Worked well.

Jim

[tuckermtn]

I have insulating blanket over the vermiculite- which now has ash over the top of it. Been good for 4 years that way

[maple flats]

I sprinkled about 1/4" refractory cement on top of mine and then sprayed a mist to barely dampen the surface. Worked good for 3 or 4 yrs now and it is quick and easy.

[lastwoodsman]

On average would you say leave about four inches from the bottom of the pan to the top of the vermiculite? Any draft problems?
Woodsman

[SeanD]

That's actually a bit too low or too much space between. If you have an 8" stack, the opening for it is going to be about 50 sq. in. The inside width of your arch is probably about 20 inches or so? That's 80 sq. inches, so you have room to come up closer to your pans if you wanted to.

The nice thing about the vermiculite is that it gives you the flexibility to close or widen the distance quickly and easily. If you lay blanket or dry splits or top you can constantly tinker with it until you get those back pans ripping. Once you mortar stuff in place it's not the end of the world, but it's harder to make improvements between boils.

Sean

[lastwoodsman]

SeanD--What do you suggest for space between the pan?

I am learning and getting some great advice here. I do have a 8 inch stack. I will start with a two to three inch gap and as you say I can adjust upon trying it.
I am putting up the stack over Christmas as I have the week off then.

My shack is at my deer hunting cabin 100 miles north of me so I can only work on it on the week-ends. But it is fun to look forward to.
Just don't want to waste btu's with this flat pan. It looks as though many of us hobbist's have 2 x 6's. This makes for great feedback on the questions asked. A lot of experience out there.
God I love the internet!!
In the old days I would have been in the library for 1/10 of the information.

Woodsman

[maple flats]

With a flat pan you should likely need about the same volume as the stack or 2.1" for a 24" wide pan. Back when I had a half pint they had you brick the firebox and then build a firewall up to 2" from the top and then it dropped back down. The boil was hardest where the firewall was.

[SeanD]

Yeah, I had my best luck at about 2". It's been uneven and inconsistent year to year because I've boiled on a block arch. I got as close to the height I wanted, then covered the fill with blanket. Last year I laid brick on top of low spots on the blanket to try to create baffles that would push the heat up against the pans (another idea I took from here).

This year I have a Mason 2x6 "real" arch, so now I'll be able to get a consistent height to the pans. I haven't bricked it yet, but I'll use a combination of blanket, splits, or fulls to get there. I'll lay them in dry so I can adjust it or if I get a flue pan (way) down the road.

Sean