Chimney lining question ?

[clambdin]

I have a masonary chimney on the outside wall of my home it is 26 ft tall with 6x6 tile liner, I am running a epa stove on it the problem I have is it just takes a longtime to warmup and establish a good draft when the chimney is cold, I have been thinking about putting a SS flex liner in it Do you all think this would help with the drafting problem ? I would probably just run the flex from the thimble up to the top of the chimney..Thank`s !

 

[BrotherBart]

When I put the SS liners in my tiled chimneys the difference was night and day as far as draft goes. I couldn't believe I hadn't done it years ago. Well, I could because I lined them three months after I discovered they even made liners these days.

 

[clambdin]

Did you insulate the liner ? one problem I have is my stove is 6 inch and my tile is 6x6 I may not have room to insulate..

 

[BrotherBart]

I only stuffed Rockwool insulation in the bottom and the top few feet. Otherwise it isn't insulated because there wasn't room. I had to go with 5.5" liners just to line the things. They both draft like a Hoover.

 

[cmonSTART]

We insulate every solid fuel liner we do for reasons I won't get into here. But, especially if your chimney is an exterior masonry unit, insulation will be very helpful with draft.

 

[BrotherBart]

We insulate every solid fuel liner we do for reasons I won't get into here. But, especially if your chimney is an exterior masonry unit, insulation will be very helpful with draft.

Both of mine are exterior masonry and if the draft was any better I would have to use pipe dampers. In fact the one in the basement has a pipe damper because it draws so hard.

After the performance I saw this year at zero degrees outside I have come to the conclusion that all of this BS about exterior masonry chimneys is exactly that. Bullsh*t.

Line'em and rock and roll.

 

[webby3650]

We also insulate our liners, it is typically because the clay liners have failed or had to be removed. When I clean a chimney that has an insulated liner I can tell where the insulation stops, the last foot or so will be typical flaky black creosote, after that it is just like powder.

 

[CarbonNeutral]

6x6 is tiny - I would have thought the only option you have is a 5.5" pipe and vermiculite?

 

[cos_man99]

I am somewhat in the same boat. I currently have 6"x10" clay flue inside diameter. I plan to upgrade to a new insert (with 6" flue outlet). I cannot fit 6" round inside my existing clay flue so I am looking at rectangular stainless liner. The question I have is whether or not to insulate. I have a 31 foot exterior chimney. If it is advisable to insulate, then I will have to go even smaller on the stainless liner so I can fit the insulation around it inside the existing clay flue. If I do not insulate I can probably go with 5.5" x 8.5" rectangular stainless liner.

 

[CarbonNeutral]

I am somewhat in the same boat. I currently have 6"x10" clay flue inside diameter. I plan to upgrade to a new insert (with 6" flue outlet). I cannot fit 6" round inside my existing clay flue so I am looking at rectangular stainless liner. The question I have is whether or not to insulate. I have a 31 foot exterior chimney. If it is advisable to insulate, then I will have to go even smaller on the stainless liner so I can fit the insulation around it inside the existing clay flue. If I do not insulate I can probably go with 5.5" x 8.5" rectangular stainless liner.

You can go Simpson Oval like I did - see sig. Mine has the same cross section area as a 6" round, but is insulated and fit nicely in my small flue.

 

[cos_man99]

I was thinking about this stuff. What do you all think?

http://www.chimneylinerinc.com/rectangleliner.htm

 

[pen]

I was thinking about this stuff. What do you all think?

http://www.chimneylinerinc.com/rectangleliner.htm

I would ONLY go the route of a square liner if you needed to maintain that exact area because you are at the minimum of your stove's requirements. If you can go to a circular liner, the round shape promotes draft better than the square.

pen

 

[CarbonNeutral]

I was thinking about this stuff. What do you all think?

http://www.chimneylinerinc.com/rectangleliner.htm

I would ONLY go the route of a square liner if you needed to maintain that exact area because you are at the minimum of your stove's requirements. If you can go to a circular liner, the round shape promotes draft better than the square.

pen

I'm not sure I buy that - the draft may be a little inhibited, but I haven't seen any evidence any where that it's much different.

Here's a thread that I started: https://www.hearth.com/econtent/index.php/forums/viewthread/39883/P22/https://www.hearth.com/econtent/index.php/forums/viewthread/39883/P22/ that discusses pressure losses between equivalently sized round and rectangular flues. The conclusion I came to was that until you get to odd aspect ratios for the rectangular, the flow characteristics (pressure losses) are very similar.

 

[pen]

I was thinking about this stuff. What do you all think?

http://www.chimneylinerinc.com/rectangleliner.htm

I would ONLY go the route of a square liner if you needed to maintain that exact area because you are at the minimum of your stove's requirements. If you can go to a circular liner, the round shape promotes draft better than the square.

pen

I'm not sure I buy that - the draft may be a little inhibited, but I haven't seen any evidence any where that it's much different.

Here's a thread that I started: https://www.hearth.com/econtent/index.php/forums/viewthread/39883/P22/https://www.hearth.com/econtent/index.php/forums/viewthread/39883/P22/ that discusses pressure losses between equivalently sized round and rectangular flues. The conclusion I came to was that until you get to odd aspect ratios for the rectangular, the flow characteristics (pressure losses) are very similar.

I can see the pressure being virtually the same, but how about the actual flow characteristics? The majority of my experience with this would come from the auto industry where most high performance intakes, intake manifolds, intercooler plumbing, exhaust manifolds, and exhausts are all more "round" in shape as to improve flow characteristics compared to stock parts which often have more square dimensions for fitment convenience.

pen

 

[CarbonNeutral]

I was thinking about this stuff. What do you all think?

http://www.chimneylinerinc.com/rectangleliner.htm

I would ONLY go the route of a square liner if you needed to maintain that exact area because you are at the minimum of your stove's requirements. If you can go to a circular liner, the round shape promotes draft better than the square.

pen

I'm not sure I buy that - the draft may be a little inhibited, but I haven't seen any evidence any where that it's much different.

Here's a thread that I started: https://www.hearth.com/econtent/index.php/forums/viewthread/39883/P22/https://www.hearth.com/econtent/index.php/forums/viewthread/39883/P22/ that discusses pressure losses between equivalently sized round and rectangular flues. The conclusion I came to was that until you get to odd aspect ratios for the rectangular, the flow characteristics (pressure losses) are very similar.

I can see the pressure being virtually the same, but how about the actual flow characteristics? The majority of my experience with this would come from the auto industry where most high performance intakes, intake manifolds, intercooler plumbing, exhaust manifolds, and exhausts are all more "round" in shape as to improve flow characteristics compared to stock parts which often have more square dimensions for fitment convenience.

pen

The flow results from the pressure difference - that is the only driving force - the hotter, less dense air. So if pressure loss (or drag) in the pipe is similar, overall flow rates will be similar. With the equipment you mention, you're talking about higher pressures (on many of them), with faster flow. Yes, these are round, and I would guess mostly because of better flow characteristics, but also because round pipe is easier to make and stronger for the same weight. You also have fluids that are somewhat corrosive in many instances that when cavitating at a sharp corner or junction could cause early failure. Finally, for engines at least, the engine performance is linked to the downstream pressure in the exhaust - sharp corners could cause turbulence that affects the engine.

With the relatively low volume/speed flow of a flue, I just don't think that an oval or rectangular pipe will make any significant difference, especially if the non-round option is insulated.

 

[pen]

I agree C Neutral, this is not an apples to apples comparison at all and there are obvious differences. I was explaining where my thoughts came from, not that it was gospel. Pressure differences cause flow, but that doesn't mean that the shape of the area the air is traveling through is any less important. For example, would wind travel through a room differently in a house with an open window and a whole house exhaust fan if there was furniture in it versus without? Or if the rooms and doors were round versus square?

The only thing I would say that I have seen direct evidence of with my stove that would support the idea of the exhaust gasses swirling inside the pipe is the following: Using my IR temp gun, if I circumnavigate my single wall pipe at any point above my stove, I'll see a range of as much as 60 degrees difference. In other words, the pipe may be at 300 pointing towards the front of the stove, 360 pointing to the right hand side, 340 pointing to the rear, and something else pointing to the left. I would have assumed that the pipe is heating differently because of the non-linear path that the exhaust gasses are traveling in as they exit. Should that pipe be squre, my belief would be that any swirling motion may see resistance as it tries to twist through the square pipe.

The question becomes, does that even make a damn bit of difference to the stove. That I just don't know.

How about going backwards? What is the point of installing a square liner anyway? Why not just use the round? What would be the advantage there?

pen

 

[pen]

Not saying this guy is doing anything scientific or simply citing what many have believed to be traditional wisdom but here's a snipit from an example of an article that supports the idea of a round chimney being better for draft.

But square and rectangular flue tiles are not the most efficient shape for venting smoke. By nature, smoke spirals upward through a flue in a helical pattern, leaving incongruous air spaces at the margins. At best, these air spaces simply take up extra room within the chimney that may be needed for additional flues; at worst, they reduce draft. Round flues are much more efficient.

here's the full article http://www.oldhousejournal.com/chimney_liners/magazine/1465

Again, not saying that this guy is speaking the truth or has done any scientific research, but all of the reading I have ever done supports this argument. I have not come across supporting the contrary. Perhaps all of us are simply wrong and just carrying on a traditional misbelief.

pen

 

[Wood Heat Stoves]

We insulate every solid fuel liner we do for reasons I won't get into here. But, especially if your chimney is an exterior masonry unit, insulation will be very helpful with draft.

Both of mine are exterior masonry and if the draft was any better I would have to use pipe dampers. In fact the one in the basement has a pipe damper because it draws so hard.

After the performance I saw this year at zero degrees outside I have come to the conclusion that all of this BS about exterior masonry chimneys is exactly that. Bullsh*t.

Line'em and rock and roll.

you are in the pnw right? as a west coaster myself, we rarely insulate the whole liner, just top and bottom seal

but on an exterior chimney in n.dakota(or other extreme cold zone) insulation could be very helpful

 

[CarbonNeutral]

I think the OP had to use either a 5.5 round, or go oval/rectangular.

To be insulated I had to go oval.

I remember reading the comment also from oldhouse - who knows?

Anyway, I need to go load some more pine in my oval lined stove

 

[cos_man99]

In my case I can go 5.5" round but will have to use the cement-like insullation that comes in bags and gets mixed. What do you think about going with 5.5" round out of a stove or insert that calls for 6". Is it that big of a difference? I have 32 feet of chimney so my thought is that it should still draft very well. Anyone have experience with the cement-style insulation?

 

[CarbonNeutral]

5.5 is 16% smaller in cross section than 6", so it's not insignificant. My guess is that it would be fine, especially with the insulation. However, depending on cost, I'd still go insulated oval, if just to avoid the mess of the vermiculite. Also it's unlikely that there won't be places that the liner won't be touching the flue - it won't stay perfectly in the middle all the way.

 

[pen]

The only time I'd be at all concerned with a 5.5 in liner on a 6 in stove is if the chimney is going to be at the minimum (or below for some people) height. Longer chimneys draft stronger (up to a certain point) and usually make up the small difference with good velocity.

In general, I have never read about a person on here who was having problems with a 5.5 in liner. But have read about people with problems using chimneys that are too large.

pen

 

[CarbonNeutral]

The only time I'd be at all concerned with a 5.5 in liner on a 6 in stove is if the chimney is going to be at the minimum (or below for some people) height. Longer chimneys draft stronger (up to a certain point) and usually make up the small difference with good velocity.

In general, I have never read about a person on here who was having problems with a 5.5 in liner. But have read about people with problems using chimneys that are too large.

pen

Agreed

 

[rdust]

In my case I can go 5.5" round but will have to use the cement-like insullation that comes in bags and gets mixed. What do you think about going with 5.5" round out of a stove or insert that calls for 6". Is it that big of a difference? I have 32 feet of chimney so my thought is that it should still draft very well. Anyone have experience with the cement-style insulation?

I'm running a 5.5 liner with poured thermix insulation. It's about 27' of liner with another 3' or so of stove pipe. During the single digit or lower weather I could have probably used a pipe damper due to the draft. I'm kinda worried about next season since my wood supply will be in much better shape.

 

[pen]

I'm running a 5.5 liner with poured thermix insulation. It's about 27' of liner with another 3' or so of stove pipe. During the single digit or lower weather I could have probably used a pipe damper due to the draft. I'm kinda worried about next season since my wood supply will be in much better shape.

Pipe dampers are about 10 bux and take about as much time and talent to install as it takes to make a grilled cheese sandwich.

pen