Help with changing from 8" to 6" chimney

[elkimmeg]

I have found Stainless 6” 24 ga in 2ft pieces for $10.00 a piece so for 40.00 I can reline the old chimney as it in only 8ft.

It is possible that you have 1700 degree chimney not 2100 degree chimney like you’ll need for the new stove install to pass muster.

There are two Ul 103 listings
UL 103 is the test standard for 1700 degrees

UL 103 type HT is tested to 2100 degrees

Without knowing to which test standard you chimney is tested to It can not be used for wood stove applications Are you using a vent threw a prefab fire place? Into the metal chimney?

I want you to know filling in the 2” airspace you could have burned you home to the ground that air a space is required to dissipate heat That is why I have a job. To protect people from themselves from doing something stupid . Now you want to re engineer another Mickey mouse setup?

You came here with severe creosote build up using your current situation. You are so damn lucky you did not have a chimney fire with the air space cavity filled.

To use a wood stove one must meet two UL standards UL 103 HT and UL 1777 there is a liner product that can be used to up grade your current system to meet both standards

Hone Saver makes the only tested and approved factory built liner adapter system.

“ now you can reline a factory built chimney and have a system listed to Ul 1777
Support for the entire liner system is provided by the patented factory built I liner adapter The lined sits on top of the double /triple wall factory built chimney without sealing off airflow between walls. In order to meet ul 1777 the lines system must be insulated with ½” home saver foil –face flex wrap Required is usage of all home saver hardware and adapters plus the Home Saver Guardian Cap”

There is another issue vertical height is very questionable being 8. You have to read the stove manufactures specs and install a venting system that meets minimum vertical height. Exceeding it will promote even better draft Are there any elbows in your current venting setup? In order to give accurate advice, we need all the details of what you have and what you are trying to accomplish A picture of you current setup would be a good starting point..
Btw one can not buy common stainless steel connector pipe and use it as a liner unless that pipe it tested and listed for the purpose. Sorry I was a little rough on you, but unfortunately I view situations that went wrong. I did not look up the UL standards and the manufacture’s liner listing If I were not trying to give correct safe advice//

Btw Englander makes a good product and where else can you talk to the factory rep before purchase.

 

[builderbob]

Hello, We have been using a old US Stove co. Forester we installed in the 80's. It had a 8" flue going into a triple wall chimney. At the time the triple way was the great thing. Well we use it for about 2 years and just started using it again 4 yrs ago. The creosote build up was very heavy I was cleaning the chimney every 2 weeks never could get the chimney hot enough to keep the creosote down. So last year I thought I would try to "fix" the problem, I packed the the inter wall of the chimney with Rock Wool. It did help keep the flue warm and still the outside was cool. We are going to change the stove this year to a new EPA Certified one. It has a 6" flue. What I need help with is if my way will work and be safe. I removed the Rock Wool so now it's back to a air cooled chimney. I want to run a 6" pipe up inside the 8" and keep it centered with using 3 screws sticking out of the 6" about every 2 feet. Then going to fill the void around the pipe with Vermiculite as it is fire proof and a good insulation. It would still be keeping cool as the 2 outer layers will still move air. Is there anything wrong with going this way? I was thinking of using 24ga steel pipe for the liner but if needed would go for stainless. Thanks for the help!
Don

One thing I haven't seen mentioned in the discussion so far------sometimes the stove you buy specifies a certain brand/type of chimney. That is, they may not only say 6", but also say UL103HT, 6", solidpack, made by "---", etc.

So, be sure you know what are the requirements for the specific stove you decide to get before you spend a bundle on chimney which is not "approved" by your stove manufacturer for that stove.

BTB

 

[n6crv]

Thanks for the info. The 2" air space was NOT filled in. The space from the chimney to any wood is closer to 3". The space that was filled in with the rock wood that has a rating of 2000deg was the space just after the stainless pipe. There still was a air space to the outside wall the the triple wall chimney. Then the 2"+ clearance to the roof framing. It was not much different then using a rock wool insulating blanket , just I used loose fill. The chimney is rated for wood stoves and something to the effect of solid fuel. When I bought it, it was from a stove shop and the stove and back wall was all gotten at the same time. The wall has 3 layers of air spaces between them. From a polished layer to what looks like louvers that keeps any heat from the wall. There was no elbows in the flue pipe. For safety was the reason that I cleaned the chimney every 2 weeks. Rock wool has a max rating before it melts that is one reason that I'm going with Vermiculite it is fire poof. Sure I would like to go with a new chimney but can't afford it. Also looked at some of the new chimney systems and they look less safe then what I have. Saw one with what looked like a 1/4 wool insulating blanket then 1/2 gap to the outer wall. I will have 3 times better insulating properties. I can see how the centering bolts could be a place for creosote to start. But it would seem to me that a corrugated liner would be even worse and alot harder to clean. Yes I came here for help and I have been getting some good advice and am taking it all in before I do anything.
Thanks!

 

[elkimmeg]

Since I'm a nationally certified building and mechanical inspector, I have to accept what is tested listed and proven.

i can't accept something engineered by indivual persons with out lab testing and UL approvals. The product I mentioned is exactly what is tested and approved.

If you could properly indetify your existing chimney as UL 103 HT or 2100 HT then that chimney can be used as it stands providing it was installed to specss and in good repair, which I would requirea report from a reconized chimney sweep before I would issue a permit. Also before issunig a permit,I would require adequate verticle chimney height, for the said stove to be installed.

I've been at this a long time. I have a gut feeling you are not going to pull a permit and you are going to do as you please and what is convient for you. You asked for code compliant safe advice.. I took the time to look up the product required tested and listed Really it is that simple. No one here can or should advise any other solution, which is not approved tested and listed.

Another solution is to remove the questionable chimney and install a 6" class A approved one in its place, so there are two correct ways to deal with your situation.

Really the best advise I can give you, is to ask you local inspector what he will approve?

 

[n6crv]

Hello Elkimmeg, I really do value your advice. The chimney and old stove was installed 20+ yrs ago. So not sure on some of the rating for the chimney. I did go up into the attic to see if I could read the UL sticker on the chimney. All I can find is UL 15752 then 2" clearance to combustibles. I know for sure at the time we got it that it was for free standing wood stoves. The stove we had was a "air tight" and it all came from the same Stove store. I can't see a brand or anything else on the chimney. I do remember the class A and something about the 103 but if it was 103HT don't know. I called the store and they don't know what they had in 1985. Getting to the point were thinking about just getting new 6" chimney pipe and Sticking it inside the 8". From what I can find the 6" insulated chimney pipe is 2" larger on the outside so should fit. That way I don't have to change anything on the roof. I can't use the same flashing on the roof for the new 6" chimney because it is about 14". Would running the new chimney inside my old one pass muster? Again thanks for your help!
Don

 

[Metal]

6" Class A won't fit inside 8" (it has a 9" OD). You can simply take the old flashing off and replace it with a flashing to fit the 6" pipe, they both should have close to a 2' x 2' base plate. 8' of Class A should cost you ~$300, plus the accessories. You can't afford not to do it right (what is your deductible for fire damage on your house?).

 

[begreen]

Why would one put class A inside of an existing triple wall flue? I would think that uninsulated stainless would be ok. My greater concern would be the length. I'd want to boost it to 12 ft if possible.

 

[n6crv]

BeGreen, the reason I was thinking of putting the new chimney inside the old, was because I didn't want to mess around with the new roof. Like having to change the flashing or changing the size of the hole thru the roof.
Don

 

[stoveguy13]

Hone Saver makes the only tested and approved factory built liner adapter system.

“ now you can reline a factory built chimney and have a system listed to Ul 1777
Support for the entire liner system is provided by the patented factory built I liner adapter The lined sits on top of the double /triple wall factory built chimney without sealing off airflow between walls. In order to meet ul 1777 the lines system must be insulated with ½” home saver foil –face flex wrap Required is usage of all home saver hardware and adapters plus the Home Saver Guardian Cap”

I would still question the liabilty involved in doing such a thing the chimney was never tested to except that re-line job the other issue you have with that is there is still the issue of the stove being tested with such a configuration if you go to most of the wood stove manf. owners manuals they are very unclear on this subject as it is diffucult to know what you are really dealing with was the first install even done correctly we refuse to sell any wood burning appliance in to setups such as this into any wood burning ZC box.

 

[BrotherBart]

...as it is diffucult to know what you are really dealing with was the first install even done correctly we refuse to sell any wood burning appliance in to setups such as this into any wood burning ZC box.

That is like saying that you won't put a liner in a masonry chimney because you don't know that the foundation was properly poured. That house had mechanical inspections and a occupancy permit issued (and if Elk did the sign off the crew is probably still in rehab). And Homesaver (good old Sooty Bob) certifies that their setup has been tested with properly installed ZC chimneys which all have to meet the same standards.

What am I missing here?

 

[begreen]

BeGreen, the reason I was thinking of putting the new chimney inside the old, was because I didn't want to mess around with the new roof. Like having to change the flashing or changing the size of the hole thru the roof.
Don

I'm agreeing with you Don. You are talking about inserting a liner and not class A pipe. I think a stainless liner would be fine and not too expensive. If you can add some length to the pipe, the stove will likely draft a bit better.

 

[stoveguy13]

...as it is diffucult to know what you are really dealing with was the first install even done correctly we refuse to sell any wood burning appliance in to setups such as this into any wood burning ZC box.

That is like saying that you won't put a liner in a masonry chimney because you don't know that the foundation was properly poured. That house had mechanical inspections and a occupancy permit issued (and if Elk did the sign off the crew is probably still in rehab). And Homesaver (good old Sooty Bob) certifies that their setup has been tested with properly installed ZC chimneys which all have to meet the same standards.

What am I missing here?

That this is not a masonry chimney that is already has some very specific test standards applied to it and that you can not always tell what the chimney was origanaly listed for they zc chimneys are not listed to except the re-line job even if good old sooty bob wants to say his system is good the stove manf. and the original chimney. manf. gives no specific listing to this sort of application. the conversations i have had with my stove manf. the stove manf. can give no specif direction how this is supposed to be done in writting. the only thing they specically will say is that the chimney must be listed to 2100 deg. i will hazord a guess the sooty bob has not had this system tested with every chimney on the market for the last 20 some odd yrs. some of th older chimneys were olny listed to 1400 deg. standard. it just is more of safe bet from my stand point to stay away from jobs like this. every one has there right to there own opion.

 

[elkimmeg]

Stove right to an oppinion you are interpeting it one way and if you follow y your own advice you will never run into a problem remember I offered two choices replace it or a second way,

the roof issue since I do a lot of roof repair and leak detection and repairing Let me share this thought with you I would much rather work witha newly shigled roon that a dried out brittle old roof Where if i look at it shingles break can't even walk on it without breaking shingles. Look at this situation in a practical way how secure do you feel having a 20+ year old chimney flange in the roof now? Me, I would opt for a new setup. knowing it is 20 years further away from developing a leak. What good will it be if in 2 years it developes a leak from aging and you loose a ceiling and suffer other water damage? If you value your roof, then think if you really want to bet on a flashing flange 20 plus years old? The normal life expectance is between 20 and 25 years. Again I not trying to bust your chops, but trying for you to think the whole situation threw Anyone with decent roofing experience, should be able to replace your old flange and re roof it in, like it belonged there in the first place