Wall Clearance ? for the Momma Bear, after lining Walls with sheetmetal

Ok, one more question, rule of thumb: I lined the corner in my shop, where I am going to install the Momma Bear. I had some 26 gage corrugated sheet iron, left over from a previous project, and I decided to go 9ft tall, and 6ft across the back, and about 7ft on one side in this corner.

In the Fisher manual it shows needed clearances of 30" on the back of the stove, and 36" to the first edge of the side of the stove from the wall. There is wafer board behind the sheet metal. My thinking is that I should be able to set it up with closer clearances now to the wall, since I have lined the wall with sheet metal, but how much can I safely decrease it? I will be running double wall stove pipe all of the way to the stove, and since I have moved the exit pipe from the back of the stove to the top of the stove, the stove pipe is effectively farther from the wall by 7 to 8" on the back of the stove.

 

You can see that I am currently closer then shown in the manual. I am currently 28 from the back of the stove to the wall, and a little over 32" from the wall to the side of the stove. However, the stove pipe itself, is still farther away from the back wall then the manual shows, by 6 inches. The manual shows 24" min. and I am currently at 30" on the stove pipe clearance from back wall, because I relocated the stove pipe to the top of stove. I would like to even be closer to the wall, but I don't want to get it too close. Opinions, experiences?

Anyway, at the 9ft height, I am going to frame in a ceiling thimble, like in my house, and run telescoping double wall pipe up to that and run the standard double wall pipe from the thimble through the roof on the top side. So, right now, I am trying to decide how close to put the stove to the walls, because that dictates where I frame in the ceiling thimble and chimney at.

 

The distance to the wall can be reduced, but your metal siding has to be 1" off the floor and separated from the combustible wall board with 1" non combustible spacers.
Reversing the metal siding will get you close.
I think you can go down to 12", but don't quote me.

 

You can reduced 50%...so 36" becomes 18", 30" becomes 15"...only for the shielded walls though...and yes, metal must be 1" off the floor, fully 1" off the wall, and wide open at the top.

 

And if you were using single wall pipe, then rear clearance could only go down to 18" (with rear exit pipe)

 

Ok, I don't need to get that close. And my sheet iron is mounted hard against the wall. I don't want to change that, now.

As is, have I gained or shall I say "reduced" my clearance requirements, any at all? Am I ok where the stove is at now?

What about adding a shorter free standing shield, (or maybe use some 1" long pipe spacers), about 3 to 4 foot high, out in front of my existing sheet metal wall? In other words, I could do the required 1" or more clearance, but, how high would this secondary wall really need to be?

 

With it mounted tight to the wall you gain zero ...if you want to do another layer, I'd say a little higher than the stove...maybe a foot?

 

Wow! I thought surly I would gain something. Ok, if I build another short wall, spaced out the min. 1" or more, and about a foot higher then the stove, does that give me the 50 percent clearance reduction numbers you stated, previously? Not that I would reduce it that much anyway.

 

In your case yes...there are however situations where other factors kick in and limit how far you can reduce things...like if you were using singlewall pipe, and 50% was going to take the stovepipe closer than 9" to combustibles, then the 9" would be minimum with properly done shielding. Doesn't apply here though.
Its common that people think as long as there is something non combustible between the stove (or pipe) and the combustible item, that helps shield it, in reality it does almost nothing, (depending somewhat on what the shield is made of) since the heat can still transfer right through the shield...even if it was a brick wall, the brick has pretty low R value, so if exposed to high temps long enough, they will transfer the heat right through to the wall/framing/etc. Your metal shield has VERY low R value, so no reduction in clearance can be taken without the ventilated air gap.

 

Is there a scenario where you can reduce 67%

 

Not that I can think of...other than a good end of season clearance sale...

 

Well, yes I could take it back down, but I just don't want to, as I like the look of it, and want something covering the wafer board but it would be more trouble then I want to space all of it out. What I am doing instead, is adding some more sheets, spaced out, up to 4-1/2 ft from the floor. Here's a picture of the first panel before I put it on the wall. It worked out good. I am now spaced off of the wall with about an 1-1/8" air gap and about 1-1/2" air gap at the bottom between the floor and bottom of spaced out panel. It's trickier then one might think to do that spacing. I ended up getting some 5/8" hex nuts and super gluing to the sheet iron to hold them in place while I shoot the screws in the wall. It's a lot of prep but finishes up well. I had just enough scrap sheet metal left to get the job done.

 

I am not completely done yet, but will finish up fairly quickly, hopefully tomorrow, if I get to work on it.

 

Ok, so I will end up with sheets spaced out from the wall, with a slightly over 1" gap and 4-1/2 ft high. I am using double wall insulated stove pipe, all of the way. I am not going to go in 50 percent, though. I think I will only reduce the clearances by about 25 to 30 percent, no more then that.

 

Not really, although I like it. It's just the color of left over sheet metal I happened to have on hand.