Prefab chimney question

[jason1238]

Hello all,

First, thanks to all of you knowledgable folks for helping educate this "fire dummy". I have been reading posts on these boards for what seems like a long time now, and I haven't seen an answer to my question, so here goes:

I have a prefab "Preway" fireplace that I will be ripping out to replace with a new freestanding wood stove. We plan to use this stove to supplement our electric heat for about 1700sf of living space. The rip out and hearth build will be the easy part. (It will not be an alcove install thank goodness!) I am really concerned with the chimney!

The existing chimney is a triple wall pipe 8" inside 11.5" inside 13", that is enclosed by a framed chase from ground level up to the roof. The height of the chimney is 19' (not counting the below grade part). I know I cannot use the current flue as is for the new stove. But is it OK to just simply reline with insulated flex? I cannot find any "clearance to combustibles" specs on flex liners. Assuming the stick built chase is in contact with the outer pipe (13" O.D.) I will have 2". Is this safe? I'm not totally against ripping the entire chase down and running Class A all the way up, but that's alot of work if I don't have to...

I just want to make sure it will be safe.

Thanks for the help,

Jason

 

[webbie]

The right way to do it is to rip it out and install class A. While it might be possible to make it safe as is, it would be a 100% "in the field" installation and would not be covered by any codes or standards. Even a simple detail like supporting the triple wall becomes suspect - most of the time, such pipe sits on the fireplace.

If, however, the piple has a valid ceiling support box and was help in place 100% independent of the fireplace, then it might be possible to reline.....but if you ask me what I would do - unless I was down to my bottom dollar, I would do away with all of it.

 

[nshif]

It almost sounds like what is there now is class A. The diameters are real close to my 8" class A. Is it stainless?

 

[jason1238]

Thanks for the info.

Only the 8" inner pipe is stainless. The other two are galvanized. There's only air space between each layer, maintained by spacers every 3 to 4 feet all the way down. I thought Class A had a ceramic blanket between??? Or is that just to keep the outer layer from getting too hot?

If I do reline, do I have to leave the air spaces open for airflow? I've read posts from Elk regarding that, but I'm not sure they spoke to triple wall.

Is there a Class A that would fit down the 8" inner? If so could I use it?

Sorry for the rapid fire questions,

Jason

 

[nshif]

I dont know if they make a non insulated Class A. Mine is insulated, which may account for the slight dia difference. Plus mine is all stainless, Ill defer to the experts. As far as a class A that would fit inside.....Id say not a chance.

 

[elkimmeg]

there are two types of class A pipe air cooled dead airspace insulation cheaper and soild pack insulation more expensive
I got to look up a product new to the market, that might save you guy some monet and is code compliant more later tonight

 

[webbie]

again, you cannot engineer your own system for airgflow. If existing triple is supported by fireplace, you must remove - you cannot hang it in some way and try to work out cooling.

This pipe is not probably not Class A of any type. It is most likely just for the preway - nothing else. Easiest job in the end it to 100% remove it. Dropping another Class A pipe down it is not really going to save you anything, and will make the job more difficult

 

[elkimmeg]

Homesaver Factory built liner Adapter Now you can reline a factory built chimney and have a system listed to UL 1777


The Adaptor makes the system work the adapter sits on top of the double wall factory built chimney without sealing off the airflow between the walls

Also ½” Homesaver foil –faced flex wrap insulation on the liner is also required to obtain the UL 1777

 

[webbie]

Homesaver Factory built liner Adapter Now you can reline a factory built chimney and have a system listed to UL 1777


The Adaptor makes the system work the adapter sits on top of the double wall factory built chimney without sealing off the airflow between the walls

Also ½” Homesaver foil –faced flex wrap insulation on the liner is also required to obtain the UL 1777

This confuses the issue. First of all, this is triple wall, which works completely different. Secondly, the kit you mention is for pre-fab fireplaces complete - not just the pipe after the fireplace has been removed.

The former advice is, IMHO, the only right way to do this.

 

[jason1238]

Ok, thanks for the input guys...I think I'm going to rip the chase down and just run some good looking stainless Class A. This gives me an excuse with the wife to relocate the whole thing. Turns out I can do it for just a little bit more than the liner, insulation, etc. I'll be re-siding the house anyway come spring, so it'll only look bad for the winter (but I'll be WARM!)

What's the deal with the airflow? I see why you would need it for the ZC prefab fireplace, but what does it matter whether the air flow still moves after upgrading the flue either by liner only or insulated liner? Just curious here...

Thanks again everyone, it's nice to know that folks like you are out there helping everyone keep the fire "in the box"!

Jason

 

[DonCT]

Is the existing pipe INSIDE the chase? If it is, you can get away with the galvalume Class A. It's alot cheaper than stainless. You will need a small (2 ft. or so) section of stainless as soon as it exits the chase.

 

[jason1238]

Yes it is inside the chase. The problem is that I would have to completely tear out at least one wall (maybe two) of the chase to get the old pipe out. It would be a heck of a job to do it carefully, and I know some of the wood siding around the chase is in rough shape and not suitable for reuse (that's the reason we're going to re-side next year--siding is shot!). So to buy the somewhat cheaper chimney, and then rebuild the chase might actually cost more than the stainless pipe alone.

Good thought though, I'll look into it. I need to price it all out anyway and I'll see how that comes out. Thanks!

Anybody have any experience with the Excel brand Class A? That's one that I can get through the local shops...


Jason

 

[AIRJET4U]

Please check out our web site

www.theventpeople.com

 

[NFreiermuth]

Jason,

Tear it out without hesitation!

But take care of it when you do. There are folks out there who need parts for the older pre-fab stuff. From what I hear, It's getting very hard to get. An ad in the local paper may net you a few bucks back towards your class A install.

Best of All...

You'll have an approved all fuel chimney in your home that you'll have confidence in it's safety.
Not to mention, a good draft

Pic's. we need pic's

 

[wahoowad]

Yeah, I wanna see pics of a chase teardown and what you put back up.

 

[jason1238]

Yeah, the "peace-of-mind" thing is a must for me.

I'll probably start tear-out of the inside stuff this weekend. Step-father's coming into town, and he's always looking for something to tear up! I'm not sure how the weather's going to be here in Cincy, but I might even start getting the chase torn down too. Not sure what I'm in for, 'cause I don't know exactly what's behind it. Can't be any worse than bare studs! The whole house is sided in that T111 crap (I'm NOT a painter!), so for the winter, I can just patch in with some new T111.

I'll get some pics to post of the patient pre-op later. I'm out of town on buisness until Friday.


In the meantime, if anyone needs parts from a Preway B-136-something-or-other (the label's kinda screwed up--not sure if there's more or it's just those numbers) I'll have them available shortly, so let me know!

I'll be gentle...I promise...

Jason