Insulate the pipe or double walled/insulated pipe

[Shari]

What is the opinion on insulating the pipe or using double walled/insulated pipe? When ever we have the $$ to buy a stove and line our interior masonry chimney I guess I am confused by which type of pipe we should be considering. We will be using a block off plate and insulating that area. We are not planning on using vermiculite for insulation inside the chimney.

edit: Should add chimney will be about 16' with a 2' extension above existing roof stack.

Shari

 

[Todd]

Since you have an interior chimney I wouldn't use insulated pipe or an insulated wrapped liner unless the chimney is in bad shape or has no clay tile liner then an insulated liner would be needed for safety. Do a search for "chimney liner kits" there are many out there on the internet.

 

[Shari]

Thanks for your reply, Todd. I forgot to mention the reason we will be lining is because we have a 1950's house so it is an older chimney and we don't want to have any problems with our city codes. If figured if we insulated we would avoid any city fire code inspection problems. Am I thinking correctly?

Shari

 

[Hogwildz]

I used pre-insulated double wall rigid, and am very glad I did.

 

[Shari]

Hodwildz,

Did you have to use flex to get through your flue or did you have to ovalize through your flue? I our case we will have to have probably two 45 degree angles to get through our flue.

Shari

 

[Todd]

I would have the chimney inspected by a local certified sweep. I think most codes state insulation is not needed unless chimney has no liner or is in bad shape. But check with your local inspector and insurance company to make sure.

 

[Hogwildz]

Hodwildz,

Did you have to use flex to get through your flue or did you have to ovalize through your flue? I our case we will have to have probably two 45 degree angles to get through our flue.

Shari

I prolly could have run the rigid all the way, but elected to use 5' or flex from the insert through the damper. I cut the damper out so I used round. No need for oval.
When I clean it, it goes all the way to the stove outlet opening with normal resistance from the brush, no hard pushing or added force is needed.
At 27' high, the draft is incredible, but not overboard. The only build up I get, is some flyash & dust on the section that comes out of the existing chimney. And even then, I get about a mason jar of ash after cleaning.
I researched alot. I am one to go overkill, rather than not enough. And in the end, when I did my install. The full flex with the added cost of insulation was only a couple hundred dollars less, so I spent the extra and went rigid. And with the double wall rigid already insulated between the shells, it went right down the chimney with no hangups or trouble. Of course the old chimney is 11" x 11", so I am sure even a flex with blanket would have went down easily.

 

[Shari]

Good description, Hodwildz. We have (I believe) a 9x12 clay lined chimney now. If I say I don't trust the inspections here is our city, trust me, I have reasons for that opinion! (VERY, very, long story....). The other reason I look at attempting to be as safety conscience as possible is that if there ever was a problem with the woodstove, we would have to go past the stove to exit our house in any emergency. We lost a loved one in a house fire not too many years ago (not stove related) so fire safety is upfront in our mind.

Shari

 

[Hogwildz]

Is that 9" x 12" inside diameter? If so, rigid insulated double wall will go down there real nice. I veleive the Duravent system I used is rated for 0 clearance also.
I called Duravent and a nice guy set me up with all the part numbers I needed to do what I wanted to do, and I ordered from online ans installed myself.
I myself would not do it any other way. Its easy to install, its easy to clean and its as safe as it gets.

 

[Shari]

I believe that is inside diameter of 9x12. I measured through the damper area as best I could and that's what I came up with.

Now, one more question regarding which is enlarging the damper area: We have a sawsall, various grinders, etc. so I don't think it would be a problem enlarging the damper area to accept a rounded pipe but my concern is that in rounding out the damper area I would think this rounding would include encroaching on to the smoke shelf inside the chimney. Hmmm... would there be any structural problem(s) if we cut into this smoke shelf by, say, 1" maximum?

Shari

 

[pinewoodburner]

I would have the chimney inspected by a local certified sweep. I think most codes state insulation is not needed unless chimney has no liner or is in bad shape. But check with your local inspector and insurance company to make sure.

Some locality do not require that the chimney be inspected by a certified sweep. To meet the UL listings for a liner, the chimney must pass the inspection to not have the insulation with the liner. My inspection did not require the liner to be insulated, but the insurance company did unless the chimney passed an inspection. My house was built in 1952, spend $150 to inspect, or $200 for the insulation for the liner. I went with the insulation.

 

[Hogwildz]

I believe that is inside diameter of 9x12. I measured through the damper area as best I could and that's what I came up with.

Now, one more question regarding which is enlarging the damper area: We have a sawsall, various grinders, etc. so I don't think it would be a problem enlarging the damper area to accept a rounded pipe but my concern is that in rounding out the damper area I would think this rounding would include encroaching on to the smoke shelf inside the chimney. Hmmm... would there be any structural problem(s) if we cut into this smoke shelf by, say, 1" maximum?

Shari

I think you will be fine. I have a metal Heatform fireplace, and I hacked the hell out of it.
The liner practically comes straight down onto the insert outlet. The straighter the shot, the easier it is to install, and easier to clean.

 

[gpcollen1]

I have my Duraliner all set up and ready to install. Maybe today and maybe not. Cutting out a piece of the damper so Ill have a nice straight shot. Outside chimney so I figured I'd try the rigid insulated variety this time. Will be rigid right to the Tee and stove.

 

[Shari]

Thanks, everyone, for all the great replies to my questions!

You know, I just have to say, there is simply awesome help here on this list! I sincerely appreciate all of it! If I ask a dumb question, make a dumb comment, etc. just correct me and set me on the right path. I am teachable. I can learn. All the help here is totally, totally appreciated!

Shari

(who bought a 4x6 utility trailer this summer and is still learning how to back it up the driveway with another load of wood)