Got some free K Wool/ Kaowool, have a question...

[imiller1974]

We just had a new boiler installed this past couple months at work. I noticed a large bag full of some type of insulation left over that maintenance was just going to throw away. I asked what it was and was told it was Kwool and I could have the whole bag if I wanted it. Well, I took that sucker home real quick. I did a little research on here and I think I've figured that in the boiler world its called Kwool, in the wood stove world it's called Kaowool. I found the company that we got the boiler from (Cleaver Brooks 450 hp) and they had some ratings on the kwool that I have. The website stated that it is rated to 2300 degrees continuous with a 3200 degree melting point. I opened the bag when I got home and discovered 7 complete rolls of 1"x3"x25' and 1 roll of 1"x2"x12'. Fantastic and free
This is the tricky part; I'm purchasing a 6" flex liner this summer and would like to use this insulation on the liner. The problem is, I don't think I can wrap it around the liner because the terra cotta liner in the chimney is only 6"x10" inside diameter. I was thinking of slightly ovalizing it and dropping into place. What I want to know is, can I cut the Kaowool into small 1"x3" strips and just start shoving and packing them in between the liner and the chimney using a rod to push them all the way down to the blockoff plate, then cap off the top? I believe I have more than enough to do it this way. The chimney is only 13' tall. I also plan on using some of the Kwool to insulate the blockoff plate. Anybody have any opinions on doing it this way?

 

[Burn-1]

I have kaowool blanket insulation on my liner and I have it held on with chicken wire. It appears to work well. I have a fairly short chimney and it definitely makes a difference in performance. But with your chimney dimensions you would be lucky to fit a 6 inch liner without any insulation so you might want to look at a smaller liner to start with. Also, the stuff I used was pretty friable so the idea for packing it in with a rod probably wouldn't work as well as you might think. Given the size of your chimney you might be better off going with loose fill or Thermix. It's definitely useful for the block off plate though.

 

[jtp10181]

You should be looking at double wall oval rigid liner with an insulation wrap built into it. If you look in the manuals for the liner kits you should find that most do not have 0" clearance to the masonry unless they have the insulation wrap AROUND them. IMO You would never get a 6" liner + plus insulation down that chimney unless you use pre-made oval liner.

 

[imiller1974]

On chimneylinerdepot.com, there is an oval liner sizing chart. If I go with a 6" liner ovaled down to 4.5"x7.5", do you think I could get some wrap on that and slide it down?

 

[jtp10181]

Might be able to, it would be over 5.5" with a 1/2" insulation wrap around it. You would want a mesh boot to put over it to keep it from ripping apart. You should check your tiles because I have found that just because it is 6" at the top doesn't mean it is all the way down. Often times the middles bow in at the bottom of each tile, or sometimes you get one half way down that cocked to one side making it a tight fit in that spot.

 

[imiller1974]

Thanks for your help. I looked down the chimney the other day with a bright flashlight and the tiles seemed pretty straight. I've got a 4 ft. straight edge that I'll stick down the chimney and lay it against the side to see how it looks tomorrow. I need to get a few work buddies over next week to pull out the old stove. I think I'm going to have to knock out a lot of the smoke shelf to get a liner down it though. I also discovered some missing mortar/cracks that will have to be fixed in the fireplace itself. I'll buy some refractory cement in a tube to do that work.

I'll do a search for the double wall oval rigid liner on google to see what I can find...

 

[DriftWood]

Sell that free wool on eBay and use the money to buy the right insulation for your liner that way you will have a UL Listed installation.

 

[imiller1974]

I think for my situation, I'll go with an ovalized 6" flex with some poured in insulation. Chimneylinerdepot.com has the bags for 50 bucks each. They had a formula for figuring out how much of the mix you need. It'll take no more that 4 bags for my needs.

 

[jtp10181]

See if they have spacers for the liner as well, it will keep it away from the sides so you don't get spots where the liner is touching the side with no insulation. Not sure if they will have ovalized spacers.