Insulating an Interior Chimney

[Sticks&Stones]

Hi All,
After much reading I've decided to try and insulate my liner. I have an interior chimney and it is 7x11 and 20' high. I had the 6" liner ovalized to 4x7.5". I know I should use a 1/2" insulation wrap but I'm nervous that it will be to tight. I was thinking of at least trying a 1/4" wrap. I was looking to see what people who do install would do? I'm leaving shortly to go pick up the insulation kit but I'd like to know what would you do.
Thank You!
Pat

 

[Sticks&Stones]

Bumping this up

 

[bholler]

1/4" does not bring you up to zero clearance for wood it will help some with performance though.

 

[Sticks&Stones]

Thank You bholler! I guess my theory is the 1/4" is better then nothing. I would love to use 1/2" but I'm not sure it will fit through.
Thank You
Pat

 

[Supersurvey]

What would you use to clean that size liner?

 

[bholler]

What would you use to clean that size liner?

The easiest thing is a rotary cleaner but you have to make sure you run in forward and reverse to clean the whole liner. We also cut brushes to fit liners for customers if they want.

 

[ccmac]

Is the flue 7x11 interior diameter? If so the the 1/2in insulation should work fine unless you have mis-aligned clay liners. I tucked an ovalized insulated liner into a 6.5x10.5in clay flue recently without any problem.

 

[Sticks&Stones]

Thank You for the replies and I will be needing cleaning rods and brushes. The terra cotta doesn't look terribly off but there is some sloppy cement work in between the tiles. I ended up buying 1/4" to play it safe, I will be pretty much busy till Sunday when the liner goes in.
Again I Appreciate all the Help/Input!
Pat

 

[Squisher]

If you run into issues with mortar snot sticking out, you can attach(duct tape, whatever) a chisel to chimney rods and knock it out. Worked for me.

 

[Sticks&Stones]

Wow Squisher that's a great move! I haven't heard of that one yet and I've been doing a ton of reading!
Thank You!

 

[Squisher]

It takes patience, and persistence.

 

[bholler]

If you run into issues with mortar snot sticking out, you can attach(duct tape, whatever) a chisel to chimney rods and knock it out. Worked for me.

We have chisels we have welded threaded fittings onto so we can use them on our rods. Now that you are doing this as a pro you should probably make some of them up.

 

[bholler]

I ended up buying 1/4" to play it safe,

Do you have the required 2" of clearance to combustibles required between the outside of the chimney and any combustible material? If not you are not playing it safe with the 1/4" you are not even meeting min code. Like ccmac said your dimensions sure sound like it should fit just fine with 1/2"

 

[Squisher]

We have chisels we have welded threaded fittings onto so we can use them on our rods. Now that you are doing this as a pro you should probably make some of them up.

I'm sure I will eventually. I'm not doing any installing though until my certification comes through this next spring. Because I won't lie about my experience I am only a qualified student right now and can't secure insurance for installations, so I don't do any. I did the 'chisel' thing when I installed my own liner last year.

 

[bholler]

I'm sure I will eventually. I'm not doing any installing though until my certification comes through this next spring. Because I won't lie about my experience I am only a qualified student right now and can't secure insurance for installations, so I don't do any. I did the 'chisel' thing when I installed my own liner last year.

Ok I am glad you are starting off slow and taking the time to learn everything properly.

 

[Sticks&Stones]

Well after all the feedback I'm going to return the 1/4" and pick up 1/2" insulation. It just makes sense and in good conscience I need to do the right thing. I'm hoping it won't turn this job into a nightmare. I'm running the electrical and pulling the liner on Sunday. I will be calling for electrical inspection and fire inspection next week. After that I can install and have another inspection for clearances. I'm getting tired thinking about all of this,lol. My PE summit arrived last night so it was Christmas in October for me. I appreciate all the insight that was provided, what a great community it is here! I will be posting up pictures of the install.
Thanks Again!
Pat