Chimney Insulation question...

[kah68]

Hi I am having my new Pacific insert installed this week. My heating guy is putting in the chimney liner, my question is does it need to be insulated all the way to the top or just where the Chimney enters the unheated portion of the attic and outside or at all. My existing chimney is 22' to the top of the cathedral ceiling, then about 20" of trusses to a 2' brick top. So for 22' the chimney runs inside the house and approx 5' is attic and outside. Oh and another question, my flue opening is 6 1/2 " by 12 or 14", will a 6" liner work with that little clearance, my stove has a 6" outlet.


Thanks

Kirk

 

[jtp10181]

What is the condition of the existing masonry flue and structure? Does it meet NFPA 211?

Most liners you are supposed to have 1" air spacers on it if there is no insulation wrap. That would never fit down what you have. An insulated 6" round will also never fit. It will be hard just to get the 6" liner down without crushing it somewhat. You would be better off using an oval liner or the simpson duraliner oval rigid.

 

[kah68]

Well from the bottom up it looks good, it is a steel box into what looks like brick chimney. By code (Ontario) we need to have a SS liner to the top, it runs mostly through the house and is drywalled in the middle of the house so there is no exposure to the outside until the last 5 feet.

 

[jtp10181]

Does it have a clay tile liner or is it just blocks? Where it is drywalled, it there drywall attached directly to the masonry, or studs directly on the masonry?

 

[crazy_dan]

If I could afford the insulation I would go with that even if it is not required. I believe that it would help keep the flue gasses temp up and decrease the possibility of creosote. Either way I do not believe the insulation will do any harm.

 

[fish]

sorry wrong post

 

[jtp10181]

i belive between the basemment and the 1 st floor youll also need a firebreak . and use as much cement board as possible if you box in the chimney . it will tend to help radiat heat from the chimney. i dont belive that you can insulate around the class a chimney at all but i could be wrong.also if you use a doudle wall stove pipe it will make it easier to clean when the time comes. also a lower clearance

He's talking about an insert, not a stove.

 

[kah68]

JTP I believe it's a clay tile liner, but I will confirm today or tomorrow, the drywall is at least 12" from the chimney front and back and 2 or more feet on the sides. I will try to post pics soon as I can. Kirk

 

[kah68]

JTP I believe it's a clay tile liner, but I will confirm today or tomorrow, the drywall is at least 12" from the chimney front and back and 2 or more feet on the sides. I will try to post pics soon as I can. Kirk

Just came off the roof, it is clay tile, approx 6x12" O.D. I didn't pop the cap off to take a look, didn't have a light to shine down will do this afternoon.

 

[kah68]

One thing I didn't mention is there are two chimney's one in the basment running a pellet stove and the one on the main floor, I don't see an attachment icon on here, how do I attach pics?

 

[begreen]

See this link for picture posting info:
https://www.hearth.com/talk/threads/6/
See this link for info on resizing pictures:
https://www.hearth.com/talk/threads/27/

 

[kah68]

JTP I believe it's a clay tile liner, but I will confirm today or tomorrow, the drywall is at least 12" from the chimney front and back and 2 or more feet on the sides. I will try to post pics soon as I can. Kirk

Just came off the roof, it is clay tile, approx 6x12" O.D. I didn't pop the cap off to take a look, didn't have a light to shine down will do this afternoon.

11 3/4" x 7 3/4" O.D. clay tile.

 

[jtp10181]

Well... same things that I said originally still apply. Since you have a clay liner the insulation may not be REQUIRED but we do it on every job we install just to be safe. The insulation wrap is the only way the liner meets the UL 1777 specs so without you are relying on the masonry structure to contain a chimney fire and meet the NFPA 211 specs.

Since you are in Canada I have no idea what listings and codes apply to you, but this is what I know about US installs.

 

[kah68]

Thanks JTP, is oval pipe common to the industry? Is it easy to source? I am affraid that my guys will tell me ' You can't use your stove because the liner won't fit...'. Also I am assuming there are oval to round adapters for the ends?

Thanks

Kirk

 

[jtp10181]

Yeah we use Simpson DuraLiner oval rigid pipe which is pre-insulated. I believe it is UL and ULC (Canada) tested. There is a 14" Oval to round flex adaptor for the bottom.

You can also get liners from many manufactures ovalized as a custom order. MaganFlex is a member here and he has mentioned there is a guy on eBay selling his liners and you can customer order it oval.