Double wall pipe

[rudysmallfry]

My single wall pipe is looking kinda tattered, so I'm going to upgrade to double wall this year. I've already got the heat shield on the stove. Just wondering if there are differences in quality in double wall pipe, or if it's all the same? I'm seeing some different prices for what seems to be the same stuff, which is why the question.

 

[RustyShackleford]

Hmm, they make some pretty un-tattered looking single-wall pipe. Why do you want to go double-wall ?
It has a number of disadvantages:

1. More expensive.
2. Harder to install.
3. You lose more heat up the chimney.

Reasons you might want to switch from single to double:

1. You don't have enough clearance to combustibles for single-wall.
2. Your stove smokes when you open the door.

In other words, double-wall is not necessarily an "upgrade". BUT, if you need it, you need it ...

 

[fossil]

What's the distance from the stove flue collar to where the stovepipe transitions to Class A chimney? What's the total height of the flue from stove to daylight? Have you had any problems with lots of creosote buildup between flue cleanings? Rick

 

[rudysmallfry]

Class A chimney is 13' tall. Pipe comes out of the top of the stove, up 2' to elbow and then 20" to thimble. The only buildup spot is in the 90 degree elbow of the single wall pipe and in the thimble.

My motive for double wall is to keep the stack warmer. Even with a nice burn going, it barely stays above 250, too low for my liking. I've posted a few times over the years about crappy short burn times. I get myself psyched out about low stack temps and keep the stove air too open, hence the crappy burn times. I'm thinking if I switch to double wall, which holds the heat better, I'll be more likely to cut the air off and get better burn times.

 

[fossil]

Toss up. Such a short run of stovepipe. In your set-up, the single wall doesn't really add much heat to the living space, but then double wall may not make a noticeable difference in flue temp. Up to you (of course). Heck, if you're gonna replace the stovepipe anyway, go ahead and give double wall a try if you're so inclined. Rick

 

[rudysmallfry]

Am I incorrect in assuming the double wall pipe will hold the heat better and reduce buildup? If so. I'll just save my $$ and get single wall again.

 

[fossil]

Am I incorrect in assuming the double wall pipe will hold the heat better and reduce buildup? If so. I'll just save my $$ and get single wall again.

No, you are correct in that understanding. Double wall stovepipe provides insulation between the interior of the flue and the living space...thus discouraging heat transfer from the stovepipe to the space...thus retaining more heat in the exhaust gas stream. Some of the stove manufacturers publish guidelines for when, based on the length of the exposed interior run of stovepipe, they recommend going with double wall. Seems to me that they're usually talking about a 10 or 12 foot (or more) vertical run. You don't have anywhere near that. That's why I'm saying that with under 4' total stovepipe, I really don't think it makes a significant difference. If you don't need double wall for clearance to combustibles (which you don't), then I'd say you might just as well stick with the more economical single wall. Rick

 

[Todd]

Class A chimney is 13' tall. Pipe comes out of the top of the stove, up 2' to elbow and then 20" to thimble. The only buildup spot is in the 90 degree elbow of the single wall pipe and in the thimble.

My motive for double wall is to keep the stack warmer. Even with a nice burn going, it barely stays above 250, too low for my liking. I've posted a few times over the years about crappy short burn times. I get myself psyched out about low stack temps and keep the stove air too open, hence the crappy burn times. I'm thinking if I switch to double wall, which holds the heat better, I'll be more likely to cut the air off and get better burn times.

I don't think 250 is too low, that's about right if your talking external temps, internal temps are about double that. Personally I like single wall, it does give off some extra heat especially while your waiting on the rock to heat up.

 

[rudysmallfry]

Yeah, I do like having the heat from the pipe. Since I live alone and am gone for 12 hours a day, I cannot keep my soapstone constantly going, so it is nice to have the pipe throwing heat while the stove heats up.

Put my mind to rest about the stack temp though. With my air shut completely on a full load of wood (newer stove, so no complete air shutoff happens), my stack hovers around 230 during secondary burn. (this is inside temp with thermometer placed 18" above stove) I clean my stove pipe once every 2 months or so. I get about a cupful of buildup between the stuff in the elbow and the thimble. the outside chimney always has very little, (it's 18', not 13' like I said yesterday) and there's very little in the straight parts of the stove pipe. The only shiny spot is where the stove pipe meets the thimble which is a logical spot for that to happen. Does this sound like a setup that runs clean, or am I right to be concerned about that low stack temp?

 

[Todd]

This 230 temp is an internal temp from a probe thermometer? If so that is very low and I would doubt the accuracy of that probe, that's just not right. I'd stick with single wall and stick a magnetic thermometer on it, probes aren't as accurate for single wall.

Anyway, you sound like your burning just fine with very little creosote. How are your stove top temps?

 

[Highbeam]

With my air shut completely on a full load of wood (newer stove, so no complete air shutoff happens), my stack hovers around 230 during secondary burn. (this is inside temp with thermometer placed 18" above stove)

You don't need to be concerned about your flue temp yet, right now your flue thermometer is broken so you have no idea what your flue temps are. There is no way that your flue is that cool. Outside temps are about half of inside temps and at 115 you could rest your hand on that flue.

A properly operating flue probe meter will report 800+ degrees F on a fully loaded, secondary burning, air shut down heritage with a minimum spec chimney.

Time to invest in a new thermometer.

 

[rudysmallfry]

It's not a probe thermometer. Just a magnet stick on type.

 

[tfdchief]

It's not a probe thermometer. Just a magnet stick on type.

250 °F should be ok, although still on the low side. As someone has already asked....what is your stove top temps?

 

[rudysmallfry]

The thermometer I have on my stove top is usually around 400 when the stack one is at 250. It's soapstone, so I'm sure that would be higher with cast iron.

 

[tfdchief]

The thermometer I have on my stove top is usually around 400 when the stack one is at 250. It's soapstone, so I'm sure that would be higher with cast iron.

Well, every set up is different. If the stove is heating well and the chimney is staying clean, then I would say you are fine with those temps. For many they would be low, but I have found that my old insert is similar. I don't know what the flue temps are but the insert is cruising and heating well with a door temp of 400.