Chimney Pipe Larger Than Damper Opening

hydestone · Nov 5, 2011

I just moved into a new house and will be installing a Jotul FC3B into an existing masonry fireplace. The clear opening in the existing damper is a approximately 5-1/2". I will be installing a 6" stainless steel pipe up through the chimney so I may need to flatten it out a bit so that it will pass through the opening. It would be an ovel where it passed throught the damper opening. The pipe will have the same cross sectional area. Any reason why this is not a good idea? The damper frame is embedded well into the surrounding masonry and I would like to avoid deconstruction and masonry work if possible.

Also, the kit comes with a closure plate for the top of the chimney opening but not include one to close off the damper frame. In my old house I packed the smoke chamber with thermafiber insulation and installed a custom closure panel on the damper frame to seal it off. Is this overkill? The plate on the top will prevent air infiltration...is there any benefit to having one on the frame as well? Sort of a belt and suspenders approach.

Thanks

jimbom · Nov 5, 2011

hydestone said:
....Sort of a belt and suspenders approach....

Good idea. Will stop convection loop in your masonry flue/house system.

Danno77 · Nov 5, 2011

If you can ovalize it and it will fit, then it should be fine. If it takes some major manhandling and you get creases and such in it, then maybe you should think of a different solution.

fossil · Nov 5, 2011

In most cases...at least in my few years associated with the forums here, I've seen the original damper and frame in the masonry chimney structure sacrificed/destroyed to make room for a nice liner fit. This only renders the original fireplace damper unusable...no effect on the structural integrity of the masonry chimney. Rick

hydestone · Nov 5, 2011

I there a way to remove pieces of the damper frame? I don't think a sawzall will even make a dent in it as it is cast iron, correct?

pen · Nov 5, 2011

hydestone said:
I there a way to remove pieces of the damper frame? I don't think a sawzall will even make a dent in it as it is cast iron, correct?

People do have luck w/ a sawzall. Just have a bunch of blades on hand. Others end up torching it.

pen

hydestone · Nov 5, 2011

I don't have a torch, but do have a bunch of sawzall blades. I suppose I could have at it to open it a bit.

DAKSY · Nov 5, 2011

Cast iron is probably the easiest material to cut with a sawzall,
& once you get most of the cut done, you can usually break sections
out with a hammer...Generally, you'll only bugger up a blade if it comes out of
the cut & the nose hits the base metal... Any remaining sharp edges can be
removed with a small grinder...

daveswoodhauler · Nov 5, 2011

I think you should be ok. I noticed that my line was a tad bit ovalized to make the fit through the damper, and just works fine. As others had said, a small portion of oval should be ok

branchburner · Nov 5, 2011

hydestone said:
I there a way to remove pieces of the damper frame? I don't think a sawzall will even make a dent in it as it is cast iron, correct?

I switched from sawzall to hacksaw halfway through and had better luck, but slow going.

hydestone · Nov 6, 2011

Sawzall with a metal blade cut through it like butter. All set.

egclassic · Nov 6, 2011

hydestone said:
I don't have a torch, but do have a bunch of sawzall blades. I suppose I could have at it to open it a bit.

Lennox makes a carbide grit( the grey colored blade is best, has diamond in it) sawzall blade that will cut through cast iron fairly quickly, I use them at work all the time. Only draw back is they are $10 each, but you should only need one, slow the saw down if you have variable speed on it. If you can't find one at HD, you may have to go to a plumbing supply house.

Loco Gringo · Nov 6, 2011

egclassic said:
hydestone said:

I don't have a torch, but do have a bunch of sawzall blades. I suppose I could have at it to open it a bit.

Click to expand...

slow the saw down if you have variable speed on it. .

Great tip. Keep the blade cool.

Jackfre · Nov 6, 2011

You cam cut it as noted, but it being CI, if you can get a good swing at it you can probably break if with a hammer. But, better wear gloves for when you rub the sides and eye protection for sure. Get really mad at it first

Jackfre · Nov 6, 2011

One other thing, get a floor jack and a 4x4 and jack up the damper.

fossil · Nov 6, 2011

If you folks would just take the time to read the thread, you'd see in post #10 above where the OP said, "Sawzall with a metal blade cut through it like butter. All set." Done deal, no more suggestions required in this case. Rick

Jackfre · Nov 7, 2011

fossil said:
If you folks would just take the time to read the thread, you'd see in post #10 above where the OP said, "Sawzall with a metal blade cut through it like butter. All set." Done deal, no more suggestions required in this case. Rick

Now, now, now! You obvoiusly haven't heard that there is more than one way to skin a cat

that said, a sawzall with the right metal blade may cut right thru it.

fossil · Nov 7, 2011

Jackfre said:
fossil said:

If you folks would just take the time to read the thread, you'd see in post #10 above where the OP said, "Sawzall with a metal blade cut through it like butter. All set." Done deal, no more suggestions required in this case. Rick

Click to expand...

Now, now, now! You obvoiusly haven't heard that there is more than one way to skin a cat that said, a sawzall with the right metal blade may cut right thru it.

Ya think? %-P I'm glad he got 'er done and can get on with the installation. Let's wait for his next question.

Loco Gringo · Nov 10, 2011

fossil said:
If you folks would just take the time to read the thread, you'd see in post #10 above where the OP said, "Sawzall with a metal blade cut through it like butter. All set." Done deal, no more suggestions required in this case. Rick

But during a search someone else may appreciate and put the suggestions to good use. I have, and still do.

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