Installing a fireplace insert with an 8 inch to 6 inch adapter to a stainless liner

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
  • Super Cedar firestarters 30% discount Use code Hearth2024 Click here

madscotsman59

New Member
Oct 30, 2020
8
portland me.
I'm getting ready to install a very heavy duty fireplace insert into a fireplace in a 219 year old colonial house here in Maine and because the brick in the chimney was so poorly laid that it can't be cleaned or trusted i had to install a 6 inch liner which is all i could fit down in the chimney. My question is this: I Need to adapt a 8 inch cast iron collector assembly that sits in slots on the top back of the stove to the 6 inch SS liner. I Found a heavy gauge steel black plate adapter/reducer on Amazon but am concerned about moisture/rust damage in the future and am wondering if a selkirk insulated type SS adapter/reducer might work?
 
I'm getting ready to install a very heavy duty fireplace insert into a fireplace in a 219 year old colonial house here in Maine and because the brick in the chimney was so poorly laid that it can't be cleaned or trusted i had to install a 6 inch liner which is all i could fit down in the chimney. My question is this: I Need to adapt a 8 inch cast iron collector assembly that sits in slots on the top back of the stove to the 6 inch SS liner. I Found a heavy gauge steel black plate adapter/reducer on Amazon but am concerned about moisture/rust damage in the future and am wondering if a selkirk insulated type SS adapter/reducer might work?
What insert is it? If it has an 8" outlet it needs an 8" liner. Also was the chimney cleaned before installing the liner? Was the liner insulated?
 
What insert is it? If it has an 8" outlet it needs an 8" liner. Also was the chimney cleaned before installing the liner? Was the liner insulated?
It's a United States stove company insert with a square cutout in the back/top of the stove that IS 6 inches but the cast iron adapter that sits on it sits down in slots and is sized for a 8 inch pipe. But i can only fit a 6 inch SS liner in the small chimney. So i'm thinking if it started out 6 inches and ends up adapted to 6 inches it should be o.k.? The chimney was cleaned and the liner isn't lined.
 
It's a United States stove company insert with a square cutout in the back/top of the stove that IS 6 inches but the cast iron adapter that sits on it sits down in slots and is sized for a 8 inch pipe. But i can only fit a 6 inch SS liner in the small chimney. So i'm thinking if it started out 6 inches and ends up adapted to 6 inches it should be o.k.? The chimney was cleaned and the liner isn't lined.
As long as the outlet size matches the liner size that is fine. But in a chimney that old insulation is a very important safety issue
 
I Thought about sealing the bottom of the chimney to the pipe and blowing in the salt treated rockwool around the liner then capping the chimney off with a new galvanized steel cap.
 
I Thought about sealing the bottom of the chimney to the pipe and blowing in the salt treated rockwool around the liner then capping the chimney off with a new galvanized steel cap.
Salt treated? That will eat your stainless liner. Why not just insulate with an approved insulation?
 
What is the ID of the chimney? Can you post a picture of the stove?
 
It has a sealed Saline salt treatment like curtains in a movie theatre. You can't even taste the salt. It makes it fireproof and heat proof but not caustic.
But rockwood is already fireproof. And yes salt will still eat stainless if there is any moisture present. Again why not just use the product listed and tested for the purpose?
 
Well i suppose at this point anything might do considering the shortages at the building supply.
What size is the existing flue? And this is not a place for the attitude of anything will do. You are dealing with stuff that could potentially burn your house down if done wrong
 
What size is the existing flue? And this is not a place for the attitude of anything will do. You are dealing with stuff that could potentially burn your house down if done wrong
7-1/2 inch flue with very poorly laid brick with the corners twisted around randomly. The liner is a non-insulated 6-1/8 inch OD, With the brick barely making contact. Outside of the brick has natural stone laid around the brick all the way to the roofline and the motor is intact and fully pointed up the entire length. There are no combustibles or lumber in contact with the entire chimney until it passes thru the ridge or the roof.
 
7-1/2 inch flue with very poorly laid brick with the corners twisted around randomly. The liner is a non-insulated 6-1/8 inch OD, With the brick barely making contact. Outside of the brick has natural stone laid around the brick all the way to the roofline and the motor is intact and fully pointed up the entire length. There are no combustibles or lumber in contact with the entire chimney until it passes thru the ridge or the roof.
That wood at the roof is what catches fire very often. There is no wood in contact at floor levels. Is it 7.5 square?
 
That wood at the roof is what catches fire very often. There is no wood in contact at floor levels. Is it 7.5 square?
Yes the flue is square, i could add two layers of 90 minute Fire x sheetrock where the chimney passes thru the roof there. It is exposed and not covered up anyways and only 8 foot above the floor at that point.
 
Yes the flue is square, i could add two layers of 90 minute Fire x sheetrock where the chimney passes thru the roof there. It is exposed and not covered up anyways and only 8 foot above the floor at that point.
Firex sheetrock is still rated as combustible. What about at floor levels?
 
At 7.5" an insulated liner should fit fairly easily.
 
Firex sheetrock is still rated as combustible. What about at floor levels?
It has a open chase from the basement that i lined with two layers of 90 minute 5/8" rock. I Don't know why they built it like that. It's a post and beam house built from ship timbers. The chase is almost 10 inches from the chimney.
 
It has a open chase from the basement that i lined with two layers of 90 minute 5/8" rock. I Don't know why they built it like that. It's a post and beam house built from ship timbers. The chase is almost 10 inches from the chimney.
Ok as long as all combustibles are atleast 2" from the chimney you should be good. Although I would still recommend pour in chimney insulation to improve performance. You don't have room for enough to get you the zero clearance rating. But you don't need it