Early Jotul C550 without Skamol Baffle Plate - Worth Upgrading? No Secondary Burn - Bonus Draft Question

[warminPA]

I have a C550 without the Skamol inserts in the baffle plates. It's just cast iron. I've seen a minor secondary burn maybe a handful of times, nothing like what you'd expect, and burn times are in the 2-4 hour range. Door gaskets replaced yearly, the flue is insulated with rockwool at the throat but no block-off plate and the chimney is insulated SS installed in 2023 when the (new-to-me) unit was installed.

22ft chimney on first floor, house is leaky on all floors, dryer is on the same floor and bathrooms/range hood on second floor. When cold, if I light a typical fire, even top-down, I'll fill the room with smoke and it won't draft. When completely cold I can feel a trickle of cold air coming in from the negative draft. If I get a raging paper fire going within 5-10 seconds it will prime the chimney with minimal smoke, or if I use gel firestarter/alcohol that will burn first and also prime the chimney without smoke. Question below.

Questions:

Would upgrading to the newer plates with the Skamol insert help with the secondary? (https://www.rockymountainstove.com/jotul-c550-rh-baffle-plate-157045/)

https://theatmosfire.com/products/air-damper - this product says it wraps around the pipe and pre-heats it and has a thermal switch to keep it warm. I don't want to do in-line because getting that chimney on through the flue throat was an absolute bear and there's no extra clearance for anything to be removed/replaced. If I put this low enough on the draw-down collar could that transmit enough heat in to the chimney to keep it primed? We're out of the house enough that we'll let it go completely out at least once or twice a week, so re-priming the draft is necessary.

Thanks in advance.

 

[begreen]

The thermowrap will possibly address the symptom, but not the cause of the problem.

It sounds like there is strong potential for negative pressure in the stove room. That makes for balky, smoky starts. The upstairs leaks may be causing the house to act like a chimney. Work hard to seal all leaks on the 2nd floor to stop the problem. Doing so may solve multiple problems by improving draft and reducing heat loss.

All about chimneys

 

[warminPA]

I may have answered my question about the Skamol plates - my C550 is the original model that only has two secondary tubes and so the baffles are different since the Skamol plates hold 3. I don't see why they wouldn't fit but I'm not 100% on that and I'm not yet up to spending the cash to find out. If they ever warp or degrade then it will be time to experiment.

begreen - thanks for that page. Explained stack effect perfectly and this is precisely what's happening.

 

[Ctwoodtick]

I have the 550 but the version with skamol panels so I’m probably not much help. My stove was bought new in 2013. How old is yours? I didn’t know they made a prior version.
My gut is telling me that the issue is not the lack of skamol panels in your situation. Probably more of what @begreen was mentioning.

 

[begreen]

begreen - thanks for that page. Explained stack effect perfectly and this is precisely what's happening.

Address this issue and you may find it's like having a new stove. Put a block-off plate up in the damper area for a notable increase in heat output.

 

[warminPA]

I think you're 100% correct and will do it this summer during the chimney cleaning. I try to do/add something every year so this year will be that. I saw in another thread (https://www.hearth.com/talk/threads/jotul-c550-block-off-plate.199234/) you replied to someone with the same issue to put some rockwool/Kaowool behind the unit itself if in an exterior fireplace. Mine sits in a masonry fireplace and the brick chimney is outside. I had an F602 CB at another house and still have a roll of the Kaowool from when I rebuilt it so I'm going to add that too.

@Ctwoodtick from what I'm reading it would be 2008, I can't even find the 2-tube baffles anywhere so it must not have been a long manufacturing run before it was changed.