Triple Wall Chimney Advice

[BuckthornBonnie]

Nice. Starlings and bluebirds have a propensity to get into chimneys here. Heck, my dad had - get this- a wood duck! somehow get into his a while ago. It was an unlined brick chimney at the time and it was unbelievable.

I’d look into removing that mesh but the manufacturer may say not to do it. The idea behind mesh is great (blocking burning bits from landing on your roof, blocking birds), but the practicality of tight mesh in the coolest part of the system isn’t there... it can lead to blockage.

Check the fastening mechanism. If it’s attached with a band, secure it tightly since you’ll be ramming it from the bottom. Use good quality stainless fasteners if they’re not supplied.

 

[kingOFgEEEks]

Another question: would it make sense to use galvalume pipe, just for the portions that are enclosed under roof? Definitely want SS outer shell for the part that protrudes outside, but could save some money on the interior pipe.

The inner layer that actually carries the smoke is still SS, it's just the outer shell that is galvalume.

 

[BuckthornBonnie]

Good question. It would be a slight cost savings and the aesthetics wouldn’t matter inside a chase. But... SS is tried and true and will outlast you and many parts of the house if you practice good burning techniques and it’s enclosed.

See if any manufacturers recommend that combination of their product. I’ve called/emailed Duravent and Selkirk for advice. Ask your code person for advice as well.

 

[EvilRoySlade]

I’m rusty on this as it’s been about 8 years since research but I see red flags.
8” on any burner better be a high btu unit or you’ll have lazy flu gas.
If you are allowing a draft baffle to control the fire that’s another layer of problems. Damper down just smolders, smolder is cool combustion, cool combustion leads to creosote. Flu temps need to stay hot to prevent condensing of combustion gasses on flu pipe walls. This also dictates the materials. There is one version that has titanium in it that is superior in many ways but it does cost.
Simple burner furnace principle is burn at optimal conditions, (high temp, low impurities) absorb that energy into a second medium like water, then regulate the water. You can control fire, but it doesn’t like it and will remind you of that if you’re not careful.
And just cause you have triple wall doesn’t mean you won’t have a chimney fire. Happens all the time if no care is given. As was told to me years ago, “you are allowing fire into your home, do so wisely”

 

[5155]

I installed an arrestor screened cap last year and it plugged in three months. At the time I thought it was a little small and too fine, I was right.
This topic reminds me I need to get up there and modify or change it.
At least the Texas like weather has passed.
It meets code the way it is though lol.

 

[BuckthornBonnie]

I’m rusty on this as it’s been about 8 years since research but I see red flags.
8” on any burner better be a high btu unit or you’ll have lazy flu gas.
If you are allowing a draft baffle to control the fire that’s another layer of problems. Damper down just smolders, smolder is cool combustion, cool combustion leads to creosote. Flu temps need to stay hot to prevent condensing of combustion gasses on flu pipe walls. This also dictates the materials. There is one version that has titanium in it that is superior in many ways but it does cost.
Simple burner furnace principle is burn at optimal conditions, (high temp, low impurities) absorb that energy into a second medium like water, then regulate the water. You can control fire, but it doesn’t like it and will remind you of that if you’re not careful.
And just cause you have triple wall doesn’t mean you won’t have a chimney fire. Happens all the time if no care is given. As was told to me years ago, “you are allowing fire into your home, do so wisely”

Some larger wood burning appliances require 8” ID... he said his does.

Yes to the potential chimney fire. That’s why code is 2” minimum to combustibles. I would personally exceed that if possible.

 

[kingOFgEEEks]

I’m rusty on this as it’s been about 8 years since research but I see red flags.
8” on any burner better be a high btu unit or you’ll have lazy flu gas.
If you are allowing a draft baffle to control the fire that’s another layer of problems. Damper down just smolders, smolder is cool combustion, cool combustion leads to creosote. Flu temps need to stay hot to prevent condensing of combustion gasses on flu pipe walls. This also dictates the materials. There is one version that has titanium in it that is superior in many ways but it does cost.
Simple burner furnace principle is burn at optimal conditions, (high temp, low impurities) absorb that energy into a second medium like water, then regulate the water. You can control fire, but it doesn’t like it and will remind you of that if you’re not careful.
And just cause you have triple wall doesn’t mean you won’t have a chimney fire. Happens all the time if no care is given. As was told to me years ago, “you are allowing fire into your home, do so wisely”

Yeah, direct from the MFR's manual, my furnace requires an 8" flue pipe. Unfortunately, they went under in 2017 and now are a fireplace and fire pit sales facility. I have the original manual, though, and everything about this furnace is industrial, and uses common parts, so I should be good for years.

(There is an old youtube video)

The plan is to install a chase around the chimney where it goes through the living space, and the chimney manufacturer gives some good detail on how to frame around it, both for in the living space, and in the attic.

Also, +1 on the chimney fire risk. I definitely want to build in a cleanout/inspection port, so I can sweep often, and be sure that it's as safe as possible.

 

[BuckthornBonnie]

It’ll be awesome, man. We almost went with a chase but liked our corner installs and exterior chimneys. Draft is definitely not an issue for us. I have a thread about one of em on FHC.

I thought about your galv question... I would personally go SS but only due to my experience with it and overkill nature of my builds.

 

[beaglebriar]

Another question: would it make sense to use galvalume pipe, just for the portions that are enclosed under roof? Definitely want SS outer shell for the part that protrudes outside, but could save some money on the interior pipe.

The inner layer that actually carries the smoke is still SS, it's just the outer shell that is galvalume.

I used the galvalume all the way up. Been there since '08 and still in good shape. As long as it's not seeing creosote I don't think rotting/rusting is much of an issue. Mine kind of swirls because it's not in the best location so I get a little creosote on the outside. It's a little rusty but not bad. I'm sure it won't last forever but maybe until I'm sick of burning wood. Lol

Since yours is going up through the house stainless skin on the last section probably isn't a bad idea though. I've had starlings get in the triple wall but they've never bothered the block chimney.

 

[Xr650jkallen]

I have the 8" supervent stuff from menards. They had it for the best price I could find anywhere online and shipping wasnt bad either. I ran the double wall stuff on the inside and the triple wall stuff through the roof and outside. We have pretty mild winters here in Tennessee, so I do have to run lower flue temps than I like, I just compensate by sweeping more often. Normally sweep it twice a season, I mostly see just a slight dusting on the inside of my flue. We left two windows cracked open all winter just to be able to hold the flue temp around 400 degrees.