New Jotul F45 v2 - smoke smell

[Rowood]

Hi,

I didn't see an exact answer to this situation in the forums before. We installed a new Jotul F45 v2 in our home in November. It's attached with new double wall pipe to our existing exterior class A steel chimney, which was swept professionally over the summer (about 25ft overall height with 2 90 degree elbows and ~36" horizontal). I did the install myself and it seems like all the joints are fitting well. Overall it's been operating well with our ash/birch/maple firewood even though the wood is probably not as seasoned as it should be (split 1yr ago, stacked and covered 6 months ago). We have long burn times, easy startup, plenty of draft.

However, over the past few days I've noticed a smoky smell coming from the stove during operation (hours after loading). Its rising from the area near the flue collar or the rear half of the top plate. There is a small gap between the collar and the double wall pipe, but I tested that with a match and it's pulling inwards pretty strongly. There are three areas with ashy buildup on the exterior of the stove pipe at joints, indicating that some smoky air must be rising in that area. See the photos below - I've also included a few images of the gasket between the cast iron flue collar and the stove - wondering if that might be the problem.

I am very grateful for any advice about how to diagnose the problem and any solutions to test! We have a baby in the house and want to be careful with our air quality.

 

[Max W]

When we looked at the f45 v2 last fall I was surprised to see the stove collar was straight vertically on the back but tapered outward on the front side. I wondered how double wall connector pipe could fit over the outside so the inside pipe could fully seat. I was told they had an adapter that fit with the connector pipe they carried. I was not impressed with the particular sales guy and would want to see the adapter if we were going further. So maybe there is an adapter for a tighter fit at that point.

 

[begreen]

Could it be the label on the pipe is disintegrating and is the cause of the smoke? Remove it to be sure.

The long horizontal run out to the tee slows down the flue gases considerably. Look for buildup there. The draft may be weakened on certain days by warmer outside temps, or the chimney location relative to the roof, or wind gusts, or the local geography. To reduce this slowdown, it's recommended to soften the first 90º by using 45s with an offset instead.



Nice closeups of the castings on the stove. They are excellent.

 

[Rowood]

Thank you for the replies! We have been having some unfavorable wind conditions. I'll verify that the smell persists with the wind coming from other directions.

In the meantime, I smelled around the stove and the smell is definitely strongest at the front of the flue collar where the pictured gasket is located, and for some reason at the top of the left-hand convective cast iron side panel near the top panel joint. I'm pretty sure at this point that the smell is coming from the stove itself and not the pipe joints. It's present at the other convective panel / top panel joint as well, and (less clearly) around the cookplate.

It's also not strictly a smoke smell - more of a gaseous, almost smoke+propane smell. Could I be experiencing gasket shrinkage or some other similar issue letting flue gases escape?

 

[begreen]

How hot have you been getting the stove? Has it been pushed harder for more heat recently?

 

[Rowood]

The stove pretty regularly rises to 600 STT, one or two times up to 650. I would say it gets between 550 and 600 almost every burn cycle (3/day). We haven't been pushing it harder lately, but it's only been running for about 6 weeks so it could still be breaking in.

 

[Todd]

Have you tried tightening the bolts on the flue collar? Maybe they’re a little loose.

 

[Crab]

I agree with Todd. When I bought my non-v2 F45, I found the flue collar bolts loose. If that is DVL, the adapter installs way too loose. I returned the adapter. My first section of pipe fits very snuggly in the collar. I may have crimped the inside flange a little, and I tapped it carefully. You couldn't ask for a better connection. I have not had any smoke smells. My set up is similar, but my horizontal run is perhsps half of yours. Please keep a carbon monoxide monitor close to the stove.

 

[Rowood]

Thank you all for the feedback!

Last weekend I took the rear heat shield off and was able to tighten the flue collar bolts very slightly - they were pretty tight already. I also took apart my double wall pipe (DuraBlack). The bolt tightening, plus cleaning the pipe out and reassembling, did not make a difference with regard to the smell I have been describing - it persists in the same locations. After doing some reading, I think it is a creosote smell. Taking apart the pipe raised a few questions that I will try to describe below.

A few images:

1) Interior of flue collar. The sharp line where the creosote/ash ends seems to indicate an OK fit between the pipe and the collar. Correct?


2) Interior of vertical pipe looking up towards elbow. I don't see anything telling here - do I? Am I missing something? For reference , the smell seems to be strongest along the front side of this section of the pipe near the bottom (lower right in this image). Is crosote getting in between the telescoping sections of pipe and then dropping down as it cools?



3) Looking into elbow from wall side - some creosote at the joint - is this a problem?


4) 2 images looking into horizontal pipe through to exterior chimney - sone creosote at the pipe/thimble joint and - more alarmingly - creosote between the walls of the horizontal pipe. What could be causing this? There is no smell around the horizontal pipe during a burn, but this seems wrong nonetheless and I wonder if it is a symptom of the same problem that is causing the smell.



Based on the above I wonder a few things:

1) Is this double wall pipe causing more problems than it's solving? Should I go back to single wall to simplify things?
2) Is there something about my install (I installed the pipe myself) that's obviously wrong that I can try to fix?
3) Do we think that the pipe is the source of the creosote smell? I don't really want to take the whole stove apart to check all the gaskets - but is that the next thing to try?

Thank you all!

 

[begreen]

To verify, this is DuraVent DVL stove pipe, correct? DuraBlack is single-wall.

It looks like it is installed correctly at the stove. The up arrow points toward the thimble. One stove flue collar screw appears to have pushed in the inner lip a little, it's probably not the issue.
The creosote buildup in the outer layer in the following shots indicates a poor seal. Are the sections fully seated and their joints fitting tightly? Were the arrows for each section all pointing toward the thimble?

Is the elbow also double-wall DVL or single-wall DuraBlack stovepipe?

If no resolution, on Monday call DuraVent tech support and send in these pictures.

 

[Rowood]

I am bringing this back up because we are still experiencing this issue.

Since January, we have tried:

-Visit from the dealer - he said the smell was "hot metal"
-Replaced double wall pipe with single wall - no change
-Cleaned chimney and pipe multiple times - very small amounts of flaky creosote, no solid buildup
-Creosote remover sticks and logs
-Spoke to Jotul rep who told us to minimize smoky startups

When we started up the stove this fall, it worked flawlessly for about a month - no smell at all. Then, we had one smoky startup (user error) where the firebox was smoking for maybe 20 minutes. All fires since then have had the same strong smell. We have another dealer coming next month to review.

There is some creosote visible in the firebox at the rear - between the bricks and a small amount on the face of the bricks. I'm almost out of ideas for what to do. Should I be taking the whole stove apart at this point to check all the seals? Could the smell be "hot metal", and if so why would it only return after a month of use (this was the same pattern last year as well)?

It's so strong it gives us a headache. We want to use the stove but we're not really able to at this point. What would you all do next?

 

[bigealta]

What is the moisture content of your wood?

 

[Rowood]

I don't have a moisture meter but it was split in March 2022 and stacked since last summer. It's all checked and makes the bowling pin sound. It's a maple/birch/ash blend.

 

[Todd]

Did you check the flue collar? I don’t think it’s the pipe. Sniff around the flue collar and the door to see if it’s stronger smell.

Does it smell when you crack a nearby window?

Only other thing I can think of is some kind of reversal down through the boost air holes in the doghouse in the lower front of the firebox. Before I plugged mine I use to get a little ash drop through there and land on my hearth.

 

[Todd]

Look at your manual parts diagram. There are two different parts to the top that have gaskets, maybe there’s a leak there? I didn’t even realize the center of the top is a separate piece. In order to remove the top to check those gaskets you need to go through the flue collar to get at the bolts holding it down.

 

[Rowood]

Todd -

Thank you! I'll try to get at thosse gaskets this weekend. Any suggestions as to what I should be looking for when I'm investigating? Just anything out of place?

Based on my experience the smell is stronger near the flue collar but I'll check the lower boost air holes as well.

 

[Todd]

I bet it the flue collar gasket then. This year I had a faint smell coming from there and I just tightened the bolts a bit. First I would take that flue collar off and replace the gasket and see what that does before digging any deeper. You should be able to take it to the local dealer and they should be able to replace or order a new one. I’ll probably replace mine next season along with my door gasket. This is season 3 for me.

 

[Kevin Weis]

Maybe an issue with enough draft in the chimney to pull the smoke through. Or too much negative pressure in the stove room.

 

[Max W]

Replacing the collar gasket looks like a next step. When you tried the single wall did you try bgreen’s suggestion of replacing the 90 deg elbow with two 45’s?