Double vs single wall chimney connector

[mol1jb]

Hey all,

Just inquiring of the differences of these 2 besides the obvious. Double wall has lower clearances. I would also consider it safer for that reason. I am assuming that in general double wall connector would draft better due to keeping flue gasses at a higher temp?

Thanks,

 

[bholler]

The only other key difference if the fact that the inner layer is stainless. Well the price is very different to. Double wall is not really safer as long as you honor the clearances for each type they are equivalent safety wise

 

[Highbeam]

I believe double wall is safer because over time the single wall rots and can fail on you, the double wall is a lifetime pipe. Also the joints of the single wall don't seal very well due to the snaplok system forcing a gap in the tapered connection.

The double wall looks better since the heat will not usually damage the paint like it does with single wall.

 

[RustyShackleford]

Single-wall is more efficient; more heat radiated into the room and less up the pipe. Of course, as noted, less heat up the pipe may be a bad thing, if it keeps you from getting enough draft.

 

[bholler]

Single-wall is more efficient; more heat radiated into the room and less up the pipe.

not true pipe is not efficient or inefficient that is up to your stove the job of the venting system is to get the exhaust out of the structure as quickly as possible while loosing as little heat as possible so your stove can work properly.

I believe double wall is safer because over time the single wall rots and can fail on you, the double wall is a lifetime pipe. Also the joints of the single wall don't seal very well due to the snaplok system forcing a gap in the tapered connection.

Well yes if you dont check your pipe single wall would be more dangerous. But double wall should be checked also it can deteriorate as well. And there is single wall pipe that is not snap lock.

 

[BobUrban]

If you are using your stove pipe to heat your home you should seriously look into a different appliance. The stove "should" be what you heat with. Pipe is just a safe transfer of noxious gases to the outside world and should be kept as warm as necessary for those gasses to remain gas until the transfer is complete.

 

[begreen]

Double-wall is also safer in that the surface temp is cooler. Touch a double-wall pipe and it will be hot. Accidentally touch a single-wall pipe and you will get a burn.

 

[RustyShackleford]

If you are using your stove pipe to heat your home you should seriously look into a different appliance. The stove "should" be what you heat with. Pipe is just a safe transfer of noxious gases to the outside world and should be kept as warm as necessary for those gasses to remain gas until the transfer is complete.

Wow, you have a demagogue politician's gift for putting words in a person's mouth: I never said I'm using the pipe to heat my home. Yes, the pipe's function is to get gaseous combustion products outside. But assuming single-wall takes care of that properly (which it does in my case, but may not in others' cases) the single wall is going to cause less heat to be lost out the chimney.

not true pipe is not efficient or inefficient that is up to your stove

And therefore, with less heat lost up the chimney, the system is going to be more efficient. The system, not just the stove.

Double-wall is also safer in that the surface temp is cooler. Touch a double-wall pipe and it will be hot. Accidentally touch a single-wall pipe and you will get a burn.

Uh, last I checked, my stovepipe is connected to my stove, and it gets very hot indeed; that's how it works, in fact. So if anyone doesn't have the sense to not touch the pipe, they probably shouldn't be that near the stove in the first place.

I seem to have really touched a nerve here with my assertion that single-wall may be a better option for some stove installations. I'm not sure why. I'll readily admit that for some installations, double-wall is definitely required.

 

[begreen]

Double-wall pipe keeps the flue gases hotter. Double-wall pipe is going to cause less heat to be lost out the connector and therefore warmer gases in the chimney. For most installations this a very good thing. Besides having a superior stainless pipe connector double-wall will generally keep the chimney cleaner and drafting stronger. For some stoves like catalytics, this is very important and recommended in the manual.

People rarely touch the pipe intentionally, but accidents can and do happen. Double-wall pipe is safer in this regard and that it is much more corrosion and rust resistant.

 

[quotejso]

Wow, you have a demagogue politician's gift for putting words in a person's mouth: I never said I'm using the pipe to heat my home. Yes, the pipe's function is to get gaseous combustion products outside. But assuming single-wall takes care of that properly (which it does in my case, but may not in others' cases) the single wall is going to cause less heat to be lost out the chimney.

And therefore, with less heat lost up the chimney, the system is going to be more efficient. The system, not just the stove.

Uh, last I checked, my stovepipe is connected to my stove, and it gets very hot indeed; that's how it works, in fact. So if anyone doesn't have the sense to not touch the pipe, they probably shouldn't be that near the stove in the first place.

I seem to have really touched a nerve here with my assertion that single-wall may be a better option for some stove installations. I'm not sure why. I'll readily admit that for some installations, double-wall is definitely required.

So I am assuming you are running double wall?

 

[Woody Stover]

the joints of the single wall don't seal very well due to the snaplok system

That's what you were using? That snap-lock pipe is scary, like the adjustable multi-piece elbows. I use welded-seam stuff if I can.

 

[RustyShackleford]

... double-wall will generally keep the chimney cleaner and drafting stronger. For some stoves like catalytics, this is very important and recommended in the manual.

I'll admit my chimney gets a little dirtier now than with my old Dutchwest (despite the BK being a vastly superior stove). But still, cleaning every 2-3 years isn't too often for me. As far as the manual, let's just say that sometimes things are put in the manual that are oversimplified.

Double-wall pipe is ... much more corrosion and rust resistant.

I think you can buy very high quality single-wall as well. Elmers makes it, notwithstanding his poor quality control (diameter variations making pipe not fit together reliably) and terrible customer service. And if single-wall IS corroding, you're more likely to see it (than in the inner wall of double-wall).

 

[quotejso]

How you like that princess I have thought about replacing the englander, of course would have to switch to double wall.

 

[bholler]

And if single-wall IS corroding, you're more likely to see it (than in the inner wall of double-wall).

Double wall is stainless interior you should easily get 25 years before you even have to start thinking about it corroding.

And therefore, with less heat lost up the chimney, the system is going to be more efficient. The system, not just the stove.

No the point of a venting system is to get the exhaust out of the chimney as fast as it can while loosing as little temperature as possible. The efficiency comes from the stove and how you run it. I am sorry but you are wrong.

All of that being said i run single wall but i only have 2' of pipe I also install lots of single wall but i will not for long runs or cat stoves.

 

[Highbeam]

That's what you were using? That snap-lock pipe is scary, like the adjustable multi-piece elbows. I use welded-seam stuff if I can.

In the shop with the nc30 I use single wall. Like rusty says, I don't mind stealing some of the chimney heat in that application. That non cat dumps 800 degree flue gas compared to much more efficient cat stoves at 300. Yes, this makes the system more efficient since less heat leaves the chimney cap but you have trade offs like less draft and faster creo accumulation if you overcool the pipe.

The single wall is cheap, available at local stores, and I wanted to try it. I know that double wall is superior.

 

[Highbeam]

Double wall is stainless interior you should easily get 25 years before you even have to start thinking about it corroding.



No the point of a venting system is to get the exhaust out of the chimney as fast as it can while loosing as little temperature as possible. The efficiency comes from the stove and how you run it. I am sorry but you are wrong.

All of that being said i run single wall but i only have 2' of pipe I also install lots of single wall but i will not for long runs or cat stoves.

I disagree with your efficiency claim. Rusty is right. Less heat up the stack means more heat delivered to the space per lb of wood. The very definition of higher efficiency. This is why condensing gas furnaces are more efficient than non condensing.

 

[bholler]

That non cat dumps 800 degree flue gas compared to much more efficient cat stoves at 300.

If it is dumping out 800 degrees shut it down harder if you cant put a damper in that is way to high. Set your stove up to run right and you wont want to get more heat off the stack.

I disagree with your efficiency claim. Rusty is right. Less heat up the stack means more heat delivered to the space per lb of wood. The very definition of higher efficiency. This is why condensing gas furnaces are more efficient than non condensing.

Yes less heat up the stack is more efficient but by using the pipe to heat you are going about it all wrong. Yes a condensing boiler is more efficient but is that the pipe that makes it that way?

 

[begreen]

In the shop with the nc30 I use single wall. Like rusty says, I don't mind stealing some of the chimney heat in that application. That non cat dumps 800 degree flue gas compared to much more efficient cat stoves at 300. Yes, this makes the system more efficient since less heat leaves the chimney cap but you have trade offs like less draft and faster creo accumulation if you overcool the pipe.

The single wall is cheap, available at local stores, and I wanted to try it. I know that double wall is superior.

Most folks are reporting more like 500F in their stacks with a 30NC. This correlates with what we also see. But most folks are not pushing their stoves to the limit. If the BK was in the shop being pushed to it's maximum limit it too would have a hotter stack temp.

 

[Highbeam]

If it is dumping out 800 degrees shut it down harder if you cant put a damper in that is way to high. Set your stove up to run right and you wont want to get more heat off the stack.



Yes less heat up the stack is more efficient but by using the pipe to heat you are going about it all wrong. Yes a condensing boiler is more efficient but is that the pipe that makes it that way?

I think we agree but you just don't like the idea of removing heat from flue gasses to extract efficiency or increase maximum output.

In the case of my shop stove, I'm already holding surface temps of 700 and trying to steal even more heat from the hot flue pipe. Not unlike a wood furnace, stealing heat from the flue is a valid method to increase output. Have you ever seen inside a caddy or yukon style wood furnace? They wrap the flue back and forth through a blast of room air to cool the flue gasses. That's where they get the heat in addition to the firebox.

Yes a condensing furnace or boiler utilizes a longer internal flue and/or second heat exchanger to steal more heat from the exhaust, that's how they get higher efficiency. They cool the exhaust so much that the water in the exhaust condenses.

 

[Highbeam]

Most folks are reporting more like 500F in their stacks with a 30NC. This correlates with what we also see. But most folks are not pushing their stoves to the limit. If the BK was in the shop being pushed to it's maximum limit it too would have a hotter stack temp.

Correct. What we're talking about here is scrubbing that wasted flue heat to extract efficiency. Think masonry heater. Burn it hard and steal the heat from the exhaust.

 

[bholler]

Have you ever seen inside a caddy or yukon style wood furnace? They wrap the flue back and forth through a blast of room air to cool the flue gasses. That's where they get the heat in addition to the firebox.

Yes and i have also cleaned many chimneys they are hooked to and most of them need more heat up the stack.

Correct. What we're talking about here is scrubbing that wasted flue heat to extract efficiency. Think masonry heater. Burn it hard and steal the heat from the exhaust.

The difference is all of the examples you are giving are done internally in the appliance. Not with part of the venting system.

 

[Highbeam]

What's the difference?

 

[bholler]

What's the difference?

One is designed by the engineers that developed the heating appliance. The other is just pulling off a random unknown amount of heat off of the venting system.

 

[stevemd]

Most folks are reporting more like 500F in their stacks with a 30NC. This correlates with what we also see. But most folks are not pushing their stoves to the limit. If the BK was in the shop being pushed to it's maximum limit it too would have a hotter stack temp.

The stack is supposed to be 500F? When the stovetop on my 30 is about 550 F my single wall stove pipe is about 280F Am I doing something wrong?

 

[begreen]

This is like car talk. Only an engineer could have this kind of discussion.
http://www.cartalk.com/content/understanding-engineers