Insert damper into double-walled stovepipe?

[kebwi]

Dampers like this:

Chimney 31330 Cast-Iron Stovepipe Damper - 7 Inch: Amazon.com: Home & Kitchen



are easy to find online, and are described as being installed by punching the sharp end through the side of the pipe. However, I think most such examples suggest simple straight-forward single-walled pipe?

Will such an installation method work on double-walled pipe or do the extra walls and the "stuffing" in between make this infeasible?

Plus, I'm not sure it'll fit, I need an extra two inches of clearance for the pin of course.

[Gulf]

Re: Insert damper into double-walled stovepipe?

I may have missed it on your chimney thread, but did you search the manufacturer who made your pipe? The best that you could hope for is that they have a damper and sleeve that mates to your existing pipe. If you are going to retro fit, you might think about going to a metal shop and get a bid on a sleeve with a damper that they have fabbed. I'm thinking that it would be better to find something that you could fit on top of your base plate or between the first two sections of pipe. Just thinking, how hard would it be to remove your base plate? There are a lot of options for you if you can.

[Neil2]

Re: Insert damper into double-walled stovepipe?

Why do you want a damper ?

[Faith In Virginia]

Re: Insert damper into double-walled stovepipe?

I believe it was suggested to him for when he puts on 20' of chimney pipe.

[kebwi]

Re: Insert damper into double-walled stovepipe?

That's the idea. I'm reconsidering whether to use the full 19' I have available, but even if I only use 15' or even 11', I'm thinking perhaps I need a damper.

...although it was never really explained to me why the strong draw of a long flue would be bad or otherwise what effect it would have on the oven's behavior.

[kebwi]

Re: Insert damper into double-walled stovepipe?

I may have missed it on your chimney thread, but did you search the manufacturer who made your pipe? The best that you could hope for is that they have a damper and sleeve that mates to your existing pipe. If you are going to retro fit, you might think about going to a metal shop and get a bid on a sleeve with a damper that they have fabbed. I'm thinking that it would be better to find something that you could fit on top of your base plate or between the first two sections of pipe. Just thinking, how hard would it be to remove your base plate? There are a lot of options for you if you can.

So, is your post basically confirming my original post, that although these dampers are described as self-boring, that only applies to single-walled and not double-walled pipe?

[Gulf]

Re: Insert damper into double-walled stovepipe?

If the damper is small enough to have some clearance inside your pipe, I think it can be made to work. The damper in your case does not have to have a perfect seal. Punching a hole through stainless steel want work real well though. If you place a block of wood inside the pipe and block it up so that you dont bend you inner pipe you can probably use the pin to make some pilot dents to help start a drill bit. You've already determined that a longer pin would have to be made.

[deejayoh]

Re: Insert damper into double-walled stovepipe?

Keith - can you use one of the prefabbed damper sections?

Damper Section

Also, I note that the larger diameter duravent products seem to have dampers in the anchor plate. Might that be a better place to install it? Seems like a sturdier piece of metal given it's relatively short length

[shuboyje]

Re: Insert damper into double-walled stovepipe?

I think the damper here is overkill. The stack in a black oven does not pressurize the oven chamber, like in a blast furnace for example. Excessive draw should not be an issue, many commercial ovens run on much taller stacks then that.

If you still want to add a damper I can certainly help you out. I'm a union sheet metal worker. Installing this stuff is what I do for a living.

[kebwi]

Re: Insert damper into double-walled stovepipe?

I certainly would be curious to get a greater breadth of input on this matter. The oven is 36" (which should give some indication of the scale of the fire) and the new stove-pipe will be 7" inner diameter. At what length might a damper become helpful...if any? I have up to 19' of stove-pipe although I'm seriously reconsidering my design because that's kind of insane, perhaps more around 11', but perhaps a touch more if I think I can get away with it, depending on the rigidity of my structural support. I've had some people advocate for a damper and others not so much.

Thoughts?

Thanks.

[shuboyje]

Re: Insert damper into double-walled stovepipe?

Air will follow the path of least resistance. The increased draw will simply pull more fresh air from outside the oven entry up the stack rather then pull air through all the resistance of the oven in any way that will effect combustion. If you were dealing with a pressurized oven chamber where there is no path of least resistance scenario the damper would make a huge difference.

If I was in your shoes I'd put it in without the damper. If by some odd chance it needs one you will be able to install it after the fact just as easy as now. You simply need a heavy gauge metal damper the is u-bolted to a rod that extends through both walls of the vent pipe. Then simply drill a hole through both walls on each side to fit the rod, push it in, and tighten the damper to it with the u-bolts. Doesn't get much easier and something we do every day.

[kebwi]

Re: Insert damper into double-walled stovepipe?

If by some odd chance it needs one you will be able to install it after the fact just as easy as now. You simply need a heavy gauge metal damper the is u-bolted to a rod that extends through both walls of the vent pipe. Then simply drill a hole through both walls on each side to fit the rod, push it in, and tighten the damper to it with the u-bolts. Doesn't get much easier and something we do every day.

I don't see how I'll reach up inside the flue to hold the damper in place while I insert the rod. The setup on my oven will make it pretty difficult.

[shuboyje]

Re: Insert damper into double-walled stovepipe?

I don't see how I'll reach up inside the flue to hold the damper in place while I insert the rod. The setup on my oven will make it pretty difficult.

You don't need to. You insert the rod, then reach up inside and u-bolt the damper to it. The first nut on the first u-bolt is a little tough, but once you get that it will begin to hold the damper in place and the rest get's much easier.