Double Arch Borad Only in Flue Area?

[user587]

Hi,

I'm planning for insulating a 2x8 w/ 2x5 drop flue rear pan. In the firebox area, I'm planning for 1" arch board and split bricks all around (including the vertical back wall of firebox). In the flue area under the drop flue pan, can I go with double arch board only? It seems pretty low cost and easy to install a double layer of board, and is appears from other posts that the board is a better insulator than bricks.

The arch board is rated 1900 degrees. I see some blankets with ratings of 2300 or 2600 degrees, would this be better/adequate for use without bricks? How would one hold the blanket in place?

Thanks! - Scott

[Bucket Head]

Scott,

The bricks really are not an insulator. They absorb heat and are used to protect whatever insulation you use from getting damaged from the firewood. Archboard would work for under the flues. You might want to consider the blanket for around the firebox- it is the hottest part of the rig. I used the 2600 degree blanket and put half bricks, or "splits", in front of it for protection. You can see some photo's of it on my Photobucket page. I am very pleased with its performance. The bricks keep the blanket in place on mine.

Steve

[Dennis H.]

It will work but it may be tough cleaning out the ash that collects back there.

[BoarsNest]

I put 1/2"-1" refractory blanket behind my bricks and then I used a combo of 1/2 and full brick depending on how they laid out. The problem I had was on the wall the door is on because of the shape of the cut outs I used the arch board from Bascom's. It was priced right but it really got beat up. I would definitely recommend brick around the firebox. You can see my pictures on flickr.

[user587]

Steve/Buckethead,

I see the rebar to support the sides - but none on the back. How well did the rebar on the sides hold up? How well did the rear wall hold up (the rear wall is split bricks over blanket, with no other support, right?). Did the loading of wood damage either the sides or rear wall?

thanks - Scott

[3rdgen.maple]

Archboard in the flue area would work but after cleaning out the ashes I think it would get beat up and need replacing in a few years. If you dont want to brick that area I would mix up a slurry of refactory cement and just coat the archboard to ease the cleaning and lengthen its life. Also like already said brick is not an insulator its a protector.

[Dennis H.]

I did just that 3rd Gen on the ramp in the rear of the evap. I will let you know how it works.

I put archs board around the entire arch and then cover it with splits. The only place I didn't cover the arch board with bricks is the ramp where I covered it with refractory cement.
I filled the area under the arch board ramp with zonalite.

[Bucket Head]

Scott,

The rebar does'nt last forever- I have replaced them once. The first set had three seasons on them, the set in the photos have two years on them. The ends burn off due to the heat. However, these seem to be holding up much better than the others, I beleive the forced draft is providing "cooling air" to them and they look pretty good. Likewise with my rebar grate spacer thing, whatever we want to call it. The first one warped and burned, but this one looks great. I'll get a lot of use out of this one. The rear wall held up great. The transition panel from the rear of the grate to the flue pan angles rearward so the bricks stay put by themselves. I have not had any damage to any of the insulation or the bricks. The only thing were careful of is that we don't hit the rebar with the wood and push any of them rearward when firing, although its not a big deal if one is bent. It's happened a couple of times and we bend it back after boiling. Also, we make sure the wood is placed in the firebox far enough so it does not come close to the unprotected insulation on the door.

Again, I'm very happy with this set-up and I'm sure your rig would perform better with it insulated like mine. I don't know what temperature the outside arch/firebox walls are now, but I can tell you before the blanket went in you could'nt stand next to it. It would burn your pants! The sides and the door would glow orange at night. That lost heat is lost no more- its boiling sap- like its supposed to be!!

Steve

[user587]

Thanks all for the responses - it helps me a lot. I think I'll use split bricks and arch board for all areas except the sides in the flue area. I like the idea of blanket, but I'm worried it'll be a bit too fragile. Not sure who's going to be loading the firebox, they may not be as careful as I would be. Thanks again for the tips!

Scott