Chimney in a semi-conditioned place - anything to add to insulation?

orange_cat

For a new EPA compliant woodstove (in case it matters) positioned next to the exterior wall the installer recommended running the chimney alongside the roof slope to have it exit at the highest point of pitched roof.

But there is no attic - only insulated on the interior and drywalled roof. So to hide the metal chimney, the dropped ceiling is proposed along the sloping portion of the roof - perhaps 7 feet long.

Anything I need to worry about (because it becomes I understand a semi-conditioned spaces?). The dropped ceiling have not been added yet, so can add insulation/vents whatever.

EdTheHeaterMan

The manufacturers instructions for that chimney system is the place to look for the necessary clearance to combustibles. If enclosed in a chase of any kind, there should be some indication of the amount of air movement inside that chase. As far as insulation is concerned, there are several fire resistant products like Kaowool and Ceramic fiber. But that may restrict the needed air flow around the pipes and supports needed to comply with the manufacture's installation instructions.

Do you have the chimney manufacturers installation manual?

Look at page 5.
https://www.lynnmfg.com/wp-content/uploads/catalog/Lynn-HVAC-Catalog.pdf

orange_cat

I have instructions but there is nothing there that I could see that is relevant?
https://morsoe.com/images/com_hikashop/upload/72611600_-_6100_b_na_pfs_646913738.pdf

It is a metal chimney that is currently below a standard drywall and the proposal is to create a dropped sloped ceiling - with another drywall layer- that will cover the chimney up to the point where it vertically exits the roof.

Jamie Hall

If your building inspector and fire marshal can live with that, OK. I wouldn't, but that's OK too. It's going to be a bear to clean, if nothing else. I presume there is a very good reason you can't go straight up and out? There are lots of chimneys in this world which don't end at the peak of the roof...

Off topic here, but in reference to your other thread -- 200 amp service is 48 KW.

orange_cat

I do not know. We were originally going to go straight up. The installer said "stack effect" - must exit at the tallest point of the roof, lets run at an angle along the roof line.

But now that they are planning to cover it with drywall I am just worried.

orange_cat

But two of the installers - from the same company - disagreed on this, so I am really worried about this.

realliveplumber

Did they obtain a permit for the job?

Jamie Hall

orange_cat said:

I do not know. We were originally going to go straight up. The installer said "stack effect" - must exit at the tallest point of the roof, lets run at an angle along the roof line.

But now that they are planning to cover it with drywall I am just worried.

The guy who said iit had to exit at the highest point of the roof doesn't know what he's talking about. Granted, to draught well there are suggested dimensions laterally and horizontally from a roof, particularly a sloped roof -- but it doesn't have to be from the peak Wandeer around a little bit and look for chimneys...

And get a different installer.

orange_cat

I cannot change the installer at this point as they already routed the chimney and roof has been done.
Morso also has "territories" so this is the distributor for the territory.
They supposedly have good reputation but when they both disagreed - that gave me a pause.

Anything I can do at this point to minimize harm?

Jamie Hall

not much Since it's already in, you're going to have to live with it, whether it makes sense or not.

Bob Harper

The stove must exit the structure via a listed factory chimney listed to UL 103HT (2,100F). This incorporates listed components such as cathedral ceiling support, firestop, attic insulation shield, roof flashing, storm collar, rain cap and extended roof bracket at min. However, listed chimney connector must be used when within 6" horizontally to combustibles/ 8" to ceilings (above 45 degrees from horizontally). You can follow a ceiling at a 45 degree angle if you maintain the clearances BUT the connector must be readily accessible and not covered with insulation. Stated clearances are air spaces. Therefore, in order to penetrate a drop ceiling, you would need to extend the chimney down to the ceiling and use connector to it.
As for height, the stove mfr. specifies the minimum total system height from the bed of the fire to the flue gas outlet plus the code required minimum above the roof: 3ft. min even with a flat roof plus 2ft above any point within 10ft. horizontally. That means with a 5/12 roof, it must extend at least 5ft measured on the uphill side.
HTH

orange_cat

Thank you, this helps.

I think I was unclear: the entire ceiling on the top floor is roof-isultation-drywall.
Then BENEATH the drywall and what was supposed to be finished ceiling, there is a metal round chimney running from the hole in the floor - along the exterior wall- then at an angle along the drywalled ceiling.

Now, to mask the chimney, a second - dropped - ceiling is proposed in this room, basically just a sheet of drywall to hide the chimney.

But I am worried.

Bob Harper

When you say 'metal chimney', is it insulated metal chimney or stovepipe? What is the roof pitch? Metal chimney cannot exceed 30 degrees from vertical in the US/ 45 degrees in Canada.
IF it is listed 'chimney properly installed and supported it can be masked with drywall at clearance to combustibles. If it is 'stovepipe' or 'connector' then it cannot be entombed above drywall.

orange_cat

What I see on the bill of materials is this:
1 Morso basic stove 6100 New "B" Model Meets New EPA Clean Burn Cerification
1 Morso base, open socket for 6143
1 ICC Double Wall Length - 6"x24"
1 ICC Double Wall 6"x40"-68" Telescopic
1 ICC Chimney 6" Round Support
1 ICC Chimney 6" Flashing Flat
2 6" x 18" Adjustable Length
5 ICC Chimney Length 48" (6")
4 6" x 45 Degree Elbow
1 ICC Chimney Radiation Shield - Enclosed (6")
1 ICC Chimney Radiation Shield - Roof (6")
1 ICC Chimney Radiation Shield Tube - Flex (6")
1 ICC Chimney Deluxe Rain Cap (6")

Is this a stovepipe or a chimney?

Jamie Hall

OK. You have what you have, and you probably need to live with it. Not the best arrangement, but I've seen worse.

That said. I would NOT enclose that sloping section in any way. Yes, it might be an eyesore, but at least if it's out in the open you can see if there are any problems with it (as an aside, if I were the building inspector for your job, I wouldn't permit you to enclose it -- but I'm not, so all I can do is comment).

orange_cat

If the job is not well done, I can still have them re-do it.
If they should not cover it with the drywall, I can still stop it.

I just find this a very opaque issue and I am looking for clarity.

Jamie Hall

There are really only three considerations here. The first is adequate draught and freedom from downdraughts. There is such a thing as the 10 foot 3 foot 2 foot rule, which is explained remarkably clearly in this link: HTTPs://woodstovepro.com/articles/understanding-the-10-foot-2-foot-3-foot-rule-how-to-determine-the-chimney-height-of-class-a-solid-fuel-pipe-above-the-roofline/

As you can see from that, the chimney or stovepipe can exit on the sloping part of the roof, provided certain dimensions are met. This is usually not a problem.

However, you have the stovepipe existing at the peak. So be it. It's there.

The other two considerations are first, clearance of the stove pipe to combustibles. This varies depending on what the stove pipe is made of. In your case, you have double wall stovepipe (good), which requires as a minimum 8 inches to combustibles -- which INCLUDES drywall. So your box, if you choose to box it in, must be fairly big. Further, the box needs to be ventilated top and bottom. The second consideration is cleaning the stove pipe. Make no mistake: the stove pipe must be swept at least once a year, even with -- perhaps especially with -- a modern airtight stove (they gum up a chimney worse than the old fashioned sort). Your chimney sweep is not going to be the least bit happy about the two bends in the pipe, and it might be advisable to consult with your sweep as to where they would like cleanouts to be and how to put them in (this is not a problem with a straight veridical pipe, obviously).

orange_cat

The installer says 2 inches to framing is all they need and to add the drywall the other side of framing is fine. When pressed on how to sweep the chimney, agreed they need to provide access at the turn.
It is approximately a 45 degree slope there.

They are the ones issuing WETT certificate. DO I need to bring a second installer to review this?

Jamie Hall

You might do very well to contact your local building inspector or fire marshal. They will have the last word on the installation -- certificate or no certificate. You might also want to talk to your homeowner's insurance people...

orange_cat

So they are using a stainless-steel double wall and a product that fits the description - does not mean that is the one - but it does say "2 inches clearance to combustibles"
https://www.markssupply.ca/ASSETS/DOCUMENTS/ITEMS/EN/SELKIRK_ALT636_Catalog.pdf

Bob Harper

The ICC chimney instructions indicate you can have two 48" lengths of 6" diameter chimney between elbows at 45 degrees maximum offset. The stove mfr. will specify how many feet of offset are allowed, how many minimum feet of chimney for the number of offsets, and distance between offsets. The sloping chimney pipe requires locking bands.
Guys, note this is in Canada, which is different from the US. Their chimney is made to withstand 2,100F @30 min tested 3 times and 1,200F continuous. They allow 45 degree ells but we don't.
Make sure they use all the requisite components.