Mysterious Combustion Issue

[Rochev]

Happy Thanksgiving y'all!
I have a king stove with recent blowers and service.
Out of nowhere a few days ago, the window started turning black and the vacuum error light was flashing.

Now the flame stays big but not lazy. Even if I turn the heat range down to 2 (out of character for this stove) and auger speed all the way down, and the OAK air as high as it'll go, the flames are big and the pellets aren't burning and building up overnight.

I felt the OAK air coming to the firebox and it's blowing in fine, but sometimes it stopped for a bit and I'm not sure that's normal.
The exhaust has been taken apart and was almost totally clean. The door gasket passes the paper test, although I could see light through a small spot but fixed it. The vacuum port in the back is clear and working. Both blowers are working normally and the exhaust is blowing out normally. Same pellets, routine, everything is the same.

I'm not sure where else to look at this point!

 

[johneh]

Are you sure that the stove is clean from air intake to exhaust termination?
Sounds to me like ana combustion air problam

 

[Rochev]

Are you sure that the stove is clean from air intake to exhaust termination?
Sounds to me like ana combustion air problam

Yes, oddly enough it's totally clear. The black soot is greasy and absolutely everywhere. This is why I'm scratching my head!

 

[johneh]

Have you changed the brand of pellets you use?
Do the pellets you use look any different than they used to?
Colour ,Texture ?

 

[Rochev]

Pellets are the same. I had 50 bags and they are getting low. Same ones I always use for both stoves

 

[Rochev]

I just replaced the exhaust motor in February and that is what fixed it last time. What are the odds a genuine US made motor with little use is already bad?

 

[johneh]

The odds are as good as a cheap motor failure in the same period
If the combustion fan is bad and not pulling the draft needed for
a good fire then you may have found the fault

 

[Rochev]

Yikes. I expected several years or more, especially since the original motor was from 2007. I'm going to reassemble and try to run it again. I've ordered a new blower but it won't be in until next week sometime.

The odds are as good as a cheap motor failure in the same period
If the combustion fan is bad and not pulling the draft needed for
a good fire then you may have found the fault

 

[ABusWrench]

Have you tried to oil/lube the motor?

 

[Rochev]

Update.
Replaced exhaust blower with new and it was working alright with no vacuum error light.
After a few minutes I had to add pellets manually as I was readjusting settings and sometime after I shut the door I noticed the vacuum error light flashing. So now I think it must be the door gasket although it doesn't seem like it. Will update again

 

[johneh]

Do the dollar bill test!

 

[Rochev]

It passed that test but the gasket is thicker on the bottom of the door causing the door to shut unevenly, maybe that's not helping.
Window turned black in just a few hours this time.

 

[johneh]

I may be wrong please correct me if I am.
When the glass gets black fast it indicates to
me that there is not enough combustion air.
So the fire burns dirty yellow black-tipped flames
Or the pellets are a very poor grade.
This is the best guide I have found

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[Washed-Up]

I think a good ole leaf blower treatment would help

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[Rochev]

Interestingly the flame isn't lazy, it's pretty good sized and quick. I took the whole exhaust and stove apart and it was fairly clean. Currently waiting on new gasket but I'm still tinkering with it.

 

[Rochev]

WOW!
Update again..
I came home to the stove totally full of glowing pellets. I've never seen it so bad, even when the original blower wasn't really working. 100% lack of air flow either in or out.

I got a blower from Amazon with a nonsense-name and it is rated .75 amp 115v. The old one is 1.75amp 120v. However, they are identical part number wise and dimensions and this one doesn't seem to have an issue blowing so I'm not sure about that area.

The OAK has no discernable air coming into the stove when running. Even if I turn the air up to 9 I don't feel anything being sucked in from outside. Before, it felt like a vacuum. There's no blockage.

I swear, I wish I spent the extra $ to get heat pumps downstairs too!

 

[johneh]

I do not think it is the combustion fan. I have seen this a few times before
Large flames and you say not lazy or black-tipped. There is only one thing
that makes a stove burn that way, lack of combustion air. Intake is partly plugged
The stove is full of ash (hidden ash traps) or the exhaust is plugged with something
We used to call it dirty stove syndrome

window started turning black and the vacuum error light was flashing

First indication

flame stays big

2nd indication

tove totally full of glowing pellets.

3rd indication
After 20 years of installing and repairing pellet stoves
all the indicators point to a stove full of ash

 

[johneh]

I just realized something nowhere in any of your posts
have you told us what make and model of stove you have
That could be a vital piece of information. To this point,
it has all been generic.

 

[blades]

Is oak capped with a screen? Have you taken a flexable long stem brush to the Oak? Kritters like to find places this time of year, Spider webs are tenacious. Then there are leaves and such. Don't know if you have had snow but seen that get sucked in and block things up. I put and S trap on the intake of my Oak- even then some snow still got in there. that's the intake side but some applies to exhaust as well.

 

[blades]

the stove is a King- no model mentioned. I think this a US Stove mfg. which makes it an import from somewhere.

 

[Rochev]

It's a King 5500m
I deep cleaned again and replaced the door gasket. It still had a vacuum issue.

I then reset the board and voila, no vacuum light. I didn't think to reset it since there's only two settings, neither of which were changed before having an issue.

The vacuum light is still off and seems to be alright for now. I have the heat range down to 3 which is odd because it's usually at least 5-6. If I adjust the feed rate or combustion air even a little, the vacuum light starts flashing and I have to reset again. I think I need a new board.

 

[Rochev]

Probably not the board as the window is black and the pot is filling up once again.

I'll post here if I figure it out for anyone else struggling with a finicky stove. I'm going to use an endoscopic camera which has been great for engine diagnostics in the past. There's plenty of air coming in and plenty blowing out so I'm not sure I'll find anything.

Also, I did check the vacuum port in the back a few times, and cleaned it with a pipe cleaner. If I unplug it, the combustion fan blows higher and it stops feeding pellets.

 

[kchace]

Did you verify that the chimney is clear all the way to the outlet? Air in has to also get out!
ken

 

[Rochev]

Did you verify that the chimney is clear all the way to the outlet? Air in has to also get out!
ken

Yes, it's installed through the wall. Everything was removed to inspect and clean. Exhaust pipes were fairly clear. It is burning better now but the pellets will pile up if I turn it up and the glass is black. The vacuum light is off though. I think the new door gasket helped but didn't fix it entirely.

 

[Rochev]

Well it seems to have fixed itself. I haven't done anything besides a regular vacuum and window clean. Has not turned black and is working fine.

This stove is by far the most difficult and temperamental unit I've ever used.