Smoke Spillage - Jotul C450 Kennebec with 5 inch liner

[oconnor]

We had our Kennebec installed about 3 weeks ago now, and I am having difficulties with smoke spillage when I load wood. The stove has a 25 foot 5 inch liner, uninsulated, in an inside chimney. I am having the installer come back to insulate the liner as per code requirements for my home/chimney style. That is another story....

Whenever I load wood, I have to be real careful to avoid getting a face full of smoke/fumes. At most, I can open 1 door 2/3 the way, and reach around to tend the fire, even after I've had the stove running for an hour, secondaries are working and showing a stove top temp near 700 degrees. (magnet mount 1 inch out from flue exit on top). It has not been cold here yet, temps around 10 C.

Questions - is insulating the 5" liner going to be enough?
My installer tells me that the 5 inch is enough for the stove, anybody else who has this stove agree/disagree?
Have not yet checked to see if an insulated 6" will fit, but if it does, is it worth me ditching the 5" liner, and eating the cost, for a 6"?
Maybe this is just a consequence of shoulder season burning - look forward to your answers.

 

[begreen]

What are your outside temps Brent? Just curious, what was the reason for going with 5" in the first place as opposed to 6"? FWIW, there also is 5.5" liner if you need a compromise solution.

 

[mcollect]

I seem to recall that Jotul specs a 6" liner, by using a 5" you are reducing the area by 2/3 . Do you also open the damper to full open for a minute before reloading? My stove aC550 never releases smoke into the room and I am a newbie.

 

[oconnor]

You are right about the 6" spec in the manual. My WETT installer indicated there would be no trouble, so I went with his advice. I haven't checked with Jotul yet though.

As for the damper, yes, I open it for for a minute or two before loading.
Going to try opening the window when I reload tonight to check the draft issue. If the window helps, then I'm thinking draft is the issue.

More thoughts?

 

[webbie]

Is your pipe flex or is it rigid. If flex,a 5" could definitely be too small. Rigid pipe drafts much better and often fits better since the OD is closer to the ID.

Personally, I would not install most double door or large door stoves with a 5" liner.....the opening is too big! There are other Jotul models (602, 118) where this may have worked better, but not the inserts.

 

[oconnor]

Thanks Web. - The liner is a flex liner.

Is there a "rule of thumb" on liner sizing? I'm asking the question as I start to search the site.

 

[oconnor]

What are your outside temps Brent? Just curious, what was the reason for going with 5" in the first place as opposed to 6"? FWIW, there also is 5.5" liner if you need a compromise solution.

Outside temps are around 10 Celcius. Inside is toasty

Unfortunately, the reason for a 5" liner is that's what he wanted to install. And no, he didn't try to clear the flue with a six inch first. And no, he didn't mention insulating it. And yes, I am a little frustrated. I went with a longstanding shop with a WETT certified installer (in fact, he owns the place.)

Now he and I have more to talk about. I will be calling Jotul next week to see if the install goes against their recommendations, at least then I'll have a leg to stand on WRT having him pull it back out.

I welcome more input. It is helping.

 

[IK_biker]

oconnor,

I hope you are also switching the blower off when reloading...

Jotul's spec calls for Ø6" liner as others pointed out.
With a 5-incher, you have essentially a 25/36 portion of the draft you would have had with the 6-incher. Thus, you are roughly 30% under the specs.

No matter what Jotul reps tell you, if I was you, I'd stay away from this particular installer in the future, certified or not.

I am far from suggesting you should eat the cost to re-line with the proper diameter liner, but I can at least advise on trying to get the installer split the cost with you, as it was their fault, and not yours. Try to negotiate some kind of a deal.
I would definitely replace the liner with a 6" one, to prevent possible problems in the long run.

And please, report back on the results of your "crack a window" test, because it is possible that a large portion of this issue could be due to odd pressure in the house, of which phenomenon you are fully aware by now, judging by your posts on the outside air kit subject. I'm curious....

 

[oconnor]

IK - thanks for the blower reminder - haven't been using it, but did remind me not to once I get it running when it's cold here.

Quick update - tried the open window last night with some benefit, but still getting spillage. Temps are at freezing this AM and tried again, still spillage.
Stove does burn well, but definately does not overdraft, and secondaries can be easily snuffed out with the air lever at 40% open. Window open/closed didn't affect the burn either- brought the air down to a stable low burn, and opened the window, expected burn quality to improve if I was having a pressure issue but didn't see it. - house is 75 years old, but has new windows - I didn't expect any of the same issues as new houses might see.

I also noted that the burn doesn't improve when I open the door a crack - instead it seems to die. Acts like it needs the blast from the primary at the front/bottom of the firebox to run - is that normal for those who have a Kennebc or stoves with similar intakes?

In the end, it all seems to point to draft as the problem.

here is my plan - go see the installer - discuss draft, insulation and liner size - money is important to me, but I don't want to "burn" bridges either. I figure the quality of a man is in his ability to fix the mistake as well as do it right first time around. My goal is a 6" insulated liner - rigid as much/far down as possible. Shouldn't be too much stopping us, as the old oil flue in the chimney isn't being used, so we could bust out it's clay liners and use ovalized if needed.

I assume there is a product out there that can go from oval rigid to flex to round stove if I need it. That would be my worst case senario.

Oh ya - the only sizing ifo I could find was for open fireplaces - Does anybody else have some better data other than the install manual for sorting out comprimises between size and height if I can't go with 6"?

Any more thoughts, "fire" away.

 

[crazy_dan]

I know at least 1 person on these forums used a 5.5" liner, sure seems like a compromise between 5" and 6" to me. That is if a 6" will not fit.

 

[webbie]

A 5" flex just sounds wrong......given the nature of flex. you have to subtract 15% at least from capacity, so that is about a 4.5" or less flue! Not good.

The rule of thumb is that a flue should be 1/10 to 1/12 the area of the door openings....

As an example - if the actual door opening was 13 inches high and 20 inches wide = 260 sq inches.

A 6" flue would be about 28 square inches, so this works.

BUT, a 5" flue would be about 20 square inches, which is small. Now figure for the deduction for flex, and you probably have an effective 17 sq inches. Even using the 12x, we are not there.....

Those are some basic rules.

 

[oconnor]

A 5" flex just sounds wrong......given the nature of flex. you have to subtract 15% at least from capacity, so that is about a 4.5" or less flue! Not good.

The rule of thumb is that a flue should be 1/10 to 1/12 the area of the door openings....

As an example - if the actual door opening was 13 inches high and 20 inches wide = 260 sq inches.

A 6" flue would be about 28 square inches, so this works.

BUT, a 5" flue would be about 20 square inches, which is small. Now figure for the deduction for flex, and you probably have an effective 17 sq inches. Even using the 12x, we are not there.....

Those are some basic rules.

Excellent info. thanks

 

[oconnor]

I was flipping thru the manual and saw something - I think that when the firebox is fully extended, the combustion air inlet becomes retracted inside of the shroud space, and is trying to draw from the same air that convective circulation/the blower is trying to circulate.

This would seem to me to not be ideal - I'm thinking that if it is so, I'll need to extend the air inlet until at least outside the surroound. Take a look at the pics below to make some sense of what I am saying.
The pic of the back of my stove was taken during the install before we extended the firebox into the room, the other 2 pics are from the manual.

I'm thinking the air inlet should have been extended whenever the stove is pulled forward in the shroud cabinet. Manual doesn't mention it though.
Is this a possible problem? (in addition to the rest of my stove issues above)

 

[IK_biker]

oconnor,

Wrong bet.

I guess you did not pay close attention during the install at what your unit looked like.

Having installed mine by myself, and having dissasembled and then re-assembled the air intake chamber (the tray-like boxy thingy with a balloon number 14 in your picture) due to curiosity, I can assure you that the pictures shown on page 6 of your manual are correct.
Look at figure 1 and 2. What is getting extended onto the hearth if the user so desires is the firebox together with its surround while the "firebox sleeve" as marked on said pictures, and the "surround panel" if such is attached to the "sleeve" stay at the fireplace's opening.

When you extended the firebox into the room, it came forward together with its shroud cabinet as you call it and all pertinent internals. What stayed back was just the surround panel and the sheet metal cage onto which it is being hung.

The shroud cabinet does not move at all relative to the firebox, and thus the path of the combustion air is not interfered with.
Again, a closer look at said pictures would reveal that the air intake ring (balloon number 13 in your picture) does not change its relative position to the rear cover (balloon No. 12) of the shroud and stays in place in both retracted and extended versions - you can see it slightly protruding at the top middle in both figures.

So, you can rule this potential cause for your smoke puff problem out.

Cheers!

 

[oconnor]

Thanks IK. I couldn't get my head around it at the time - once I read your post, it all made sense. Next time I install - more pics, more instruction manual before hand.

I did give a viewing of the Govt of Canada video I saw referenced in another thread http://www.ec.gc.ca/cleanair-airpur/videos/Woodstove_mgt-Eng.wmv , and gave it the full try this AM, including the part of not having to open the doors for an hour or 2. I am now a full believer in top down fire lighting, including the newspaper knots trick. Much less smoke in the house (cause the door stays closed) and more heat earlier than my previous top down attempts.

It was wierd watching Jon Gulland play the newbie - like watching Mike Holmes take one of those how to build a deck seminars at Home Depot.

Still going to get myself an insulated 6" liner though.