New install in old chimney, complicated with many options

[bkoltai9]

Hi everyone! This is my first time posting and thanks to all of you for reading and (hopefully) offering good advice.

After last winter's cold even here in Mississippi, I swore that I was buying a wood stove because our heat pump was mostly useless and expensive last winter.

I bought an Ashley wood circulator (BEC95 I think is the model #), which is not the best recommended after recent EPA redesign, but its what was available locally.

So, my issue is that I don't have a clear idea how best to install the stove pipe or chimney liner. What I have to work with is as follows:

This house was built around 1920 and had a chimney in the wall between the living room and bedroom with dual fireplaces. 6 or 7 years ago (before I purchased it) the falling apart house was mostly rebuilt, including a new metal roof. The previous owner had no interest in using the fireplaces and had the chimney cut off below the roof in the attic crawl space.

Earlier this year I began consideration of how to heat with wood and I looked at the chimney top in the attic, which looked like two flues, each about 4x16 with a line of brick between them. Since I only need one wood heater, I went ahead and busted out the entire center column, right down to the floor. Now I have about 6 feet of 12x16 which then opens up to a wide chamber below that you can enter from both sides. My plan is to put the wood heater in the living room and keep an access door from the bedroom.

So, with that back story out of the way, I need to figure out how to run the stove pipe. I had thought to just use cheap stove pipe and that was all there was to it, but I had no idea. My friend who cleans chimneys told me I ought to check out flex chimney liner and since then, I've started learning about all kinds of options.

My first and biggest question is whether I should rebuild the rest of the chimney or just use what I have and just run stovepipe through the roof. At first it seemed this would be much easier, but I'm not so sure anymore.

I've been reading about rigid vs flexible chimney liner and I think I can use either one. However, I'm not sure if I'd be better with chimney liner or insulated stove pipe. I had an idea to use a hybrid with liner dropping from the top of the cutoff chimney and insulated pipe going through the roof, but I've been told this would be impractical if not impossible. I guess the top piece that would suspend a flex liner would not support the weight of insulated stove pipe above it, and I'm not sure how I'd connect the pieces.

I'm also wondering about how to connect at the base. I have 6" diameter opening coming horizontally out the back of the wood heater. I wonder if having the flex pipe curve and attach directly to the stove would be better or should I drop straight down to a T and run a horizontal stove pipe into the back of the heater.

Also, I wonder with flex or rigid liner or with stove pipe, how do I hold it in place? I've had a recommendation to use metal plumbers tape and masonry screws to wrap and fasten to the chimney.

Another question is insulation. I've been recommended to save my money and buy cheap fiberglass insulation and just tear off the paper backing, rather than the expensive flue liner insulation.

I guess that's a good start. As I work my way through these issues, I'll probably add more to this thread. I may post some drawings or pictures if necessary.

Please chime in if you have any thoughts or solutions, and especially if you have experience working with a cutoff chimney.

Thanks everyone!

 

[transmogrifire]

Sounds like you have the space to just build an entire class A chimney in the existing flu. start with a t and the appropriate support, you may have to fabricate the support for the t out non combustible to maintain the required rear clearance of the stove. you can add a stabilizer where it exists the brick in the attic space and may not require any further support depending on the slope of your roof and how far the chimney will extend beyond.

 

[bholler]

I had an idea to use a hybrid with liner dropping from the top of the cutoff chimney and insulated pipe going through the roof, but I've been told this would be impractical if not impossible. I guess the top piece that would suspend a flex liner would not support the weight of insulated stove pipe above it, and I'm not sure how I'd connect the pieces.

That is what i would recommend either flex or rigid Not stove pipe it is not for that purpose in the chimney wrapped with insulation wrap and then a anchor and adapter plate to change over to class a chimney

I'm also wondering about how to connect at the base. I have 6" diameter opening coming horizontally out the back of the wood heater. I wonder if having the flex pipe curve and attach directly to the stove would be better or should I drop straight down to a T and run a horizontal stove pipe into the back of the heater

you want to have a tee

Also, I wonder with flex or rigid liner or with stove pipe, how do I hold it in place? I've had a recommendation to use metal plumbers tape and masonry screws to wrap and fasten to the chimney.

Where are you worried about holding it fast? the only place you need to worry about is at the bottom and you should do a block off plate ant the bottom to close off the bottom of the flue and that will hold the pipe steady.

Another question is insulation. I've been recommended to save my money and buy cheap fiberglass insulation and just tear off the paper backing, rather than the expensive flue liner insulation.

absolutely not it is not safe or approved for that application for the liner it self you need to use liner insulation and anywhere else you can use roxul.

 

[bkoltai9]

Thanks guys for responding quickly. Some clarification and some questions.
I'm still learning the appropriate terminology. Where I mentioned insulated stove pipe, I think what I meant was class A chimney.

Sounds like you have the space to just build an entire class A chimney in the existing flu. start with a t and the appropriate support, you may have to fabricate the support for the t out non combustible to maintain the required rear clearance of the stove. you can add a stabilizer where it exists the brick in the attic space and may not require any further support depending on the slope of your roof and how far the chimney will extend beyond.

It seems to me that building an entire class A chimney would be very expensive. I'm not opposed to it if it turns out to be the most sensible install, but I wonder how the costs compare to chimney liner. I'm considering Flex King or Flex King HD since they have DIY warranty.

That is what i would recommend either flex or rigid Not stove pipe it is not for that purpose in the chimney wrapped with insulation wrap and then a anchor and adapter plate to change over to class a chimney

What exactly do you mean by an anchor and adapter plate? I'd like to see if I can figure out how to do this kind of install, but I have no idea what parts are really appropriate. Also, are class A chimney parts interchangeable, or do they only work with their own brand/model?

Where are you worried about holding it fast? the only place you need to worry about is at the bottom and you should do a block off plate ant the bottom to close off the bottom of the flue and that will hold the pipe steady.

What exactly is a block off plate? Is that something that attaches to the cleanout part of the T?

Since posting this morning, I checked out the chimney with a tape measure and it looks like the opening is 13"x18". From the top of the chimney to the floor is a little more than 11' and it's 2' up to the roof.

I have been told two different things regarding the total chimney height. I've heard that it needs to be 2' above the peak of the house if it is less than 10' horizontal from the peak. I've also heard the same thing, with 6' horizontal from the peak. I measured and it's a little more than 8' from the peak. Do I need to go 2' above the peak or not? If not, how high above the roof do I need to go? Getting 2' above the peak of the house will surely add at least 6' of chimney.

 

[bkoltai9]

Considering class A chimney options.

A local place keeps these Ameri-vent in stock and pretty inexpensive.

http://www.ameri-vent.com/products/hs-hss/chimney-section

It's a little more than $100 for a 4' section. It doesn't look nearly as good as a duravent I've seen at another local installer, but the duravent is more than double the price. I'm wondering if anybody has any experience with the Ameri-vent products. I think it's stainless/galvanized triple layer.

 

[bholler]

Here is an example of what you want it is a top plate you would attach the liner to the bottom of and the top has the connection for the class a chimney. And yes all class a chimney parts are brand specific. A block off plate is a plate that you make to colse off the bottom of the chimney opening with a hole in it to let the liner pass thru. You need to be 3 feet above where the chimney exits the roof or 2 feet above anything with in 10 feet.

It's a little more than $100 for a 4' section. It doesn't look nearly as good as a duravent I've seen at another local installer, but the duravent is more than double the price. I'm wondering if anybody has any experience with the Ameri-vent products. I think it's stainless/galvanized triple layer

This is only ul 103 rated not the ul 103ht that you need for a wood stove it wont work You also want insulated not air cooled it works much better

 

[bkoltai9]

Here is an example of what you want it is a top plate you would attach the liner to the bottom of and the top has the connection for the class a chimney.

What brand/model is this? Can you provide a link? How would I couple the flex line to the bottom section? I noticed most flex line couplers I see have a special hose clamp looking piece integrated.

This is only ul 103 rated not the ul 103ht that you need for a wood stove it wont work You also want insulated not air cooled it works much better

The following passage is from page 1 of the AmeriVent HS installation instructions. It looks like it's rated UL 103HT and there's a description of the construction and insulation. Your thoughts?

• AmeriVent Model HS/HSS all-fuel chimney systems meet the requirements of UL Standard #103 HT when installed in accordance with our installation instructions. AmeriVent Model HS/HSS all-fuel chimneys are designed to be installed as complete systems, including supports, pipe sections, caps, firestops, attic insulation shields, etc.

• The AmeriVent Model HS/HSS all-fuel chimney construction consists of three walls of metal, using air and woven ceramic fiber blanket insulation. The inner and intermediate walls are stainless steel, and the outer wall is galvanized steel. This chimney is listed (UL 103 TYPE HT) for venting flue gases not exceeding 1000°F under continuous operating conditions. In addition, UL has conducted additional tests at 1400°F for one hour and 2100°F for 10 minutes to verify compliance with UL test standards. The Model HS/HSS all-fuel chimney is approved, accepted, or listed by UL, NFPA, IMC and UMC.

• The AmeriVent Model HS/HSS all-fuel chimney is suitable for use on the following types of wood, coal and oil appliances.

Residential Appliances

Ranges, warm-air furnaces, water heaters, hot-water heating boilers, 15 psi or less steam boilers, floor furnaces, wall furnaces, room heaters, and fireplace stoves.

Building Heating Appliances

Nonresidential building heating appliances, steam boilers operating at not over 1000°F flue gas temperature.

• The Model HS/HSS Chimney may also be used where type B gas vents are permitted, but should not be used for forced- draft or induced-draft appliances that have a positive pressure in the vent.

• Installing or using our chimney or parts of our chimney in ways other than those specified in our instructions might be hazardous; therefore, the chimney must be installed exactly as shown in these instructions.

 

[bholler]

The following passage is from page 1 of the AmeriVent HS installation instructions. It looks like it's rated UL 103HT and there's a description of the construction and insulation. Your thoughts?

I read the manual for the other one there sorry that would work but personally i would go with regular double wall insulated pipe it has thicker insulation which keeps the temps up higher and a smaller outer diameter

That adapter is just the first pic i found most class a chimney manufacturers will have a plate like it. You would need to check that it would fit your flex or rigid liner also but the manufacturer should be able to answer that. The way you would attach it would depend on the liner you choose but ss rivits would work for all types just different lengths for different liners and light wall liners require backing washers to keep the rivit from pulling through the thin metal.

 

[bkoltai9]

That adapter is just the first pic i found most class a chimney manufacturers will have a plate like it. You would need to check that it would fit your flex or rigid liner also but the manufacturer should be able to answer that. The way you would attach it would depend on the liner you choose but ss rivits would work for all types just different lengths for different liners and light wall liners require backing washers to keep the rivit from pulling through the thin metal.

I've been searching through some of the online catalogs and having trouble finding a plate like that. I'm inclined toward duratech because I can find parts locally if need be, but I'm open to any brand. If you can post links for one or more of those plates, I'd certainly be grateful.

Also, I'm still wondering about fastening a flex liner to the bottom of the plate. I'm assuming the flex liner would fit over the outside of the plate bottom and it seems to me, that would be an opportune place for system leakage. In a normal install, that flex liner top opening is at the top of the chimney and it's held from the outside, rather than the inside, and it wouldn't matter anyway if it did leak. In the middle of the attic, would that be a potential problem? (SEE IMAGE)

 

[bholler]

your chimney will be under a vacume any leakage will be air coming into the liner not the other way around. And if it fits properly it should not be an issue anyway. Attaching it like i said before can be done in different ways depending on the liner and plate. You will need to call the suppliers about that plate i know most companies make them but they are not common so they may not be in the regular catalog.