ss liner question

[paulie]

When installed, they ran the new ss liner through the old pipe.. would this be consider "insulated" ? there is a small gap of air between the two, old one 6" new 5.5" this is in an exterior chimney, in wooden chase.

 

[jtp10181]

What kind of venting is the "old" one? Was this an old ZC box and you put in an insert?

 

[paulie]

yes, it was a Heatilator 36"

 

[jtp10181]

Most of the Heatilator prefabs use a 8" or larger ID prefab air cooled chimney. You said your old one was 6" was it Class A? Is it a prefab ZC box heatilator unit? Do you know the model?

Basically if the old chimney system was not tested to the HT listing (2100 deg) the new liner should be fully insulated all the way to the top. Also if the old chimney is air cooled the out shell must not be sealed off at the top so it can still breathe.

 

[paulie]

i do beleive it is 6", the 5.5" just fits down it, and not sure if it is class A or not. It was installed 11 yr ago when house was built, I would assume so..but not sure. and yes, it is a zc box, not sure of model # .... 36" heatilator Don't all chimney pipes have to be HT tested? And if it is, then with the new liner inside the old one, would you consider this a natural insulation? And I know the top of the chimney has been closed forever. Air cooled??? the chase is aprox. 2.5' x 4' 24' hieght. Not positive new at this tech stuff. so anyway, just very cuirious, I read alot about insulated chimneys, wonder if mine would fall into that catagory

 

[swestall]

What is the outside diameter of the old stack and did it have more than one wall? Like tripple wall with 9" outside diameter?

 

[paulie]

What is the outside diameter of the old stack and did it have more than one wall? Like tripple wall with 9" outside diameter?

don't know ...could only see the top of fire box where pipe connected to it Iknow not much help from a guy looking for answers...sorry, I was just thinking ,"even if it's a single wall pipe" that if it had approx half inch air gap between the old and the new that it would naturally have SOME insulation factor there.

 

[jtp10181]

Is this really a heatilator BRAND and just the old heatilator "style" heatform unit. In the inside a fairly thick metal shell? There is no Heatilator open wood unit that I have ever seen or heard of that uses 6" ID chimney.

 

[paulie]

no, it is indeed a Heatilator brand," Heatilator name plate still on it" I may be wrong on the size of the pipe, if I am , it is NO more than 8" it is a thick metal shell with a thin fire brick "look a like " type inside walls. I am also thinking back, and believe it has a double wall original pipe

 

[jtp10181]

So... sounds like you have a insert in a ZC Box. One of the trickiest installs to get right. The liner should be fully insulated from bottom to top, unless the original chimney was tested to 2100 deg (usually they are not). Also the top should not be totally sealed. The outer shell of the old pipe was probably an air cooling chamber and this must be open still to allow it to cool. Otherwise the air inside become stagnant and can get much hotter than the original clearances were designed for. This can, over time, lead to nearby combustibles starting on fire.

We have put a few liners down old prefab chimneys this year. Always use 6" with 1/2" insulation wrap. Its tight but it goes down. Not sure why they installed a 5.5" uninsulated liner in yours. Sounds like you might have a Class A chimney in which case it should be tested to 2100 and you are fine. Ask the dealer that installed it if your old chimney is class A or air cooled. Also, if you can get the model number off your old Heatilator I can look it up and see what chimney system it used.