Arrgh! My 5" liner is not enough draft. Help!

[lonef6r]

Previously I had a Kent insert that was sized for a 6" flue. I sized it down to 5" because the existing terracotta liner was 6.5"x15" ID. It worked fine for twenty years and then bit the bullet. So I bought myself a new Clydesdale, which also had a recommended 6" liner. Well I already had the 5" in there and it seemed to work so I figured I'd give it a try. You know what's coming next. It didn't draft enough. Dang.
So after a winter of no fires spring is here. I have a 21 foot interior chimney. I pulled the stove out and now am having a devil of a time getting the old liner out. My options as I see them are 1) Insulate the 5" liner with pour in insulation and hope that that improves the draft adequately. 2) Pull out the 5" liner somehow and hope that I can cram a 6" down there. 3) Try an ovalized liner. Do they make oval to round converters. 4) Go against recommendations and use the existing terracotta flue without a liner. 5) Sell the stove, which I love, and find one that will work with a 5" flue. 6) Hire a professional and let them figure it out. ??????????

 

[leeave96]

Why not just have the clay liner you already have knocked out and a 6 inch insulated liner installed. It ain't that hard to knock out the old liner.

Good luck,
Bill

 

[lonef6r]

Well I have two questions. 1) How do you knock out the liner 20' down? 2) The existing liner sticks up and the top plate and rain cap attach to it. If I destroy the liner, is it a bear to plug that gap between the remaining chimney and the flue?

 

[laynes69]

We had a 32' chimney and I also needed a 6" liner. With our flue size a 6" flex wouldn't fit. I decided to install a 5.5" rigid liner and insulate with loose pour insulation. We haven't had any issues with draft going this route. Knocking out the liner would have been last resort for me. Even then, there were a couple of tight places but the liner went in okay.

 

[remkel]

I am a practical man- let the professionals handle it.

 

[Hardrockmaple]

I had my 38 ft. clay liner beat out last year. Heavy duty drill and rods with a beater end (specific to the job) made short work of the original liner. Dropped a 6 in. liner down, hooked up stove.....took two days for the professionals.

 

[begreen]

I'd put in oval Duraliner. It's preinsulated, 4.75" x 7.75", and should cure your draft issue pretty well. They make a round to oval flex pipe to ti in the stove. Download the Simpson Duraliner catalog to look at the options.

 

[cmonSTART]

The best and proper way to do it is to have the old clay knocked out and install a properly done insulated 6 inch liner. Oval pre insulated MIGHT work if the flue doesn't have any offsets. I know Magna-flex makes some decent stuff also but it's not overly flexible once ovalized.

Be very careful about pouring insulation down your flue right now. It may improve things, but it also may not have a significant effect. If it doesn't you will have no way to "undo" it, as the insulation becomes a permanent part of your flue.

 

[branchburner]

Are you absolutely sure it's a draft problem exclusively due to flue size? Just wondering how many fires you tried, and were they in much colder weather that your initial attempt, to rule out the possibility of the new stove learning curve.
Did the Kent have a much smaller firebox that your new 2.4, and was it the same burn technology as the new stove?

 

[ddddddden]

If most of the 21' is interior, insulation shouldn't be an issue. . .maybe put in some mineral wool at the top. +1 to exhaust all possibilities before concluding that the flue is too small. Like Branchburner said, an EPA stove with a secondary burn baffle in the exhaust path is going to seem to have a weak draft compared to a pre-EPA stove with an unrestricted exhaust. To my limited understanding, a 5" flue should draft fine, until the volume of smoke exceeds the capacity of the flue. I dunno if a 2.4-cu-ft load could generate this much exhaust, but I think what would happen is that it would draft okay up to the point in the burn at which the exhaust volume exceeded the flow capacity of the flue. I would also think that a smaller load would go through the burn cycle with no problem. Did you ever try to burn a half-load? What exactly were your symptoms? Not enough draft to get a good burn going? Smoke spilling out of the stove?

 

[ddddddden]

I just scanned back. . .Branchburner didn't say exactly what I indicated, but I believe that's where he was going with comparing burn techologies. If you decide to go with plan C and swap the stove, maybe look at a Lopi with a bypass. . .should draft as well as anything with the bypass open for startup.

 

[cmonSTART]

It certainly wouldn't surprise me if the 5 inch flue was creating some issues. When reducing from a 6 to a 5 inch liner, you lose 1/3 of your total cross section. That's a huge difference in CFM the chimney can move. I'm not saying the 5 inch can't work, but it's certainly won't be breathing like it should.

Does the stove smoke out the door when loading? Dirty glass? Hard to get a fire going?

 

[Fsappo]

Have a decent hearth shop with an NFI certified tech come out with a tile smasher, remove the tiles and drop a 6" insulated liner down. You may be lookin at $1600-$2000 total, but your kinda of in a pickle. Thats option one. Option 2 would be to drop a 5x11 oval liner down, may be a little bit cheaper. It sounds like you may be in a tad over what the average homeowner should be doing.

 

[pen]

Tell us about the fuel you are using? It may simply be that the old stove could chew through wood that was less than perfectly seasoned and the new stove needs very dry wood. Not accusing you of having poor quality wood just stating an observation that we have seen over and over.

pen

 

[Backwoods Savage]

Good post Pen! Rule out the obvious first before spending big dollars.

 

[BrotherBart]

Yeah I am wondering about the wood too. My prime mover is a big firebox burning into a 21' 5.5" liner and it drafts too hard sometimes.

Year one with it when I was still cutting in spring and burning in fall I had some smoke back problems. Not anymore with the dry wood. Thanks hearth.com.

 

[My Oslo heats my home]

[quote author="Remkel" date="1307326455"]I am a practical man- let the professionals handle it.[/quote

But its no fun

 

[lonef6r]

To answer as many questions as I can. The old Kent did have a smaller firebox, as much as a third smaller. It had a high efficiancy design, the air circulating tubes, but not the ceramic baffle.
As to symptoms, it belches smoke when opened, the glass is dirty, but it starts up OK. Sometimes, if I can get a hot enough start on a burn I can get it to a place were the belch is minimal. As to wood, I didn't keep that close track, but most of my wood was over a year old. I burned smaller loads predominantly. I burned maybe ten times at most during the cource of the winter, the belches weren't horrendous, but enough to piss off the wife.

 

[cmonSTART]

Smoking out the door can be a symptom of an undersized liner.

Do you have any overly large kitchen or bathroom exhaust fans running? Does it make a difference if you crack a window before opening the stove door? Just trying to weed out some other causes of the smoking. Though really, I think it's an undersized liner.

 

[begreen]

To answer as many questions as I can. The old Kent did have a smaller firebox, as much as a third smaller. It had a high efficiancy design, the air circulating tubes, but not the ceramic baffle.
As to symptoms, it belches smoke when opened, the glass is dirty, but it starts up OK. Sometimes, if I can get a hot enough start on a burn I can get it to a place were the belch is minimal. As to wood, I didn't keep that close track, but most of my wood was over a year old. I burned smaller loads predominantly. I burned maybe ten times at most during the cource of the winter, the belches weren't horrendous, but enough to piss off the wife.

Did you notice the stove behaving better when it was really cold outside and performing more marginally during our normal 30-40F winter temps?

 

[Bub381]

I'm new at this too but OAK wouldn't help or isn't there 1 on this stove? Another thing i like about a 50 TL,the bypass if needed.

 

[lonef6r]

So, I've built scaffolding around the chimney, pulled the 5" liner. I fabricated my own tile breaker thinking that the factory version MIGHT be too large to fit my narrow, 6" x 15" flue. It didn't work. Maybe it was the CRS instead of the tempered steel. Any ideas?