Very black soot..Why?

[John Fortier]

Cleaned stove on Sat. by Sun. night noticed a very black soot on the glass and burn pot. Cleaned again this evening (Mon.) Would it be from lack of air flow? Opened that up a bit. Heat is fine, just curious to the really black as opposed to normal gray. Lot of build up in the burn pot also. Extra scrapping needed.

 

[SidecarFlip]

Your mixture is too rich. You can't control the fuel (pellets), you can control the air (oxidizer).

 

[doghouse]

Have you checked the entire exhaust pathway? May need to be cleaned. Leaf blower!

 

[bogieb]

Your mixture is too rich. You can't control the fuel (pellets), you can control the air (oxidizer).

Okay, just because I'm a dummy that is always willing to learn, what exactly does "mixture too rich" mean?

 

[JDenyer236]

Okay, just because I'm a dummy that is always willing to learn, what exactly does "mixture too rich" mean?

Too much fuel and/or not enough air.

 

[Bioburner]

Okay, just because I'm a dummy that is always willing to learn, what exactly does "mixture too rich" mean?

Like when you leave the choke on a engine and gets to much fuel and spews black smoke, and fouls the plugs.

 

[SidecarFlip]

Okay, just because I'm a dummy that is always willing to learn, what exactly does "mixture too rich" mean?

Essentially, it's like a carburetor on your lawnmower. If the deposites are black soot, it's either not getting emough combustion air, it's getting too much fuel or the exhaust system is restricted. If you cleand it and I presume the exhaust system is not blocked (venting is clean, cleanout Tee is emptied, combustion fan chamber is clean and HX passages are clean) then it's a combustion air issue rather than a fuel rate issue because fuel rate is controlled more by the control board than you.

You need to open your draft slide a bit more to allow more air into the burn pot. You want a sharp active flame with a hint of blue at the base of the flame in the pot. Conversely, you can increase the combustion fan speed (if you can control it) to provide more negative draft, but the easiest way is allowing more combustion air manually via the draft slide (if you have one).

All stoves operate on the same principles, air to fuel ratio and if the a/f ratio is way off, the fuel burns incompletely and deposits black soot (ash). Give it more air.

Keep in mind that basic control of a stove is controlled by the alogrithms contained in the intergreated circuits on your control board and they don't always provide the perfect a/f ratio, especially in the lower heat ranges so you need to add a bit of air to 'lean' out the a/f ratio and achieve a complete burn.

 

[bogieb]

Essentially, it's like a carburetor on your lawnmower. If the deposites are black soot, it's either not getting emough combustion air, it's getting too much fuel or the exhaust system is restricted. If you cleand it and I presume the exhaust system is not blocked (venting is clean, cleanout Tee is emptied, combustion fan chamber is clean and HX passages are clean) then it's a combustion air issue rather than a fuel rate issue because fuel rate is controlled more by the control board than you.

You need to open your draft slide a bit more to allow more air into the burn pot. You want a sharp active flame with a hint of blue at the base of the flame in the pot. Conversely, you can increase the combustion fan speed (if you can control it) to provide more negative draft, but the easiest way is allowing more combustion air manually via the draft slide (if you have one).

All stoves operate on the same principles, air to fuel ratio and if the a/f ratio is way off, the fuel burns incompletely and deposits black soot (ash). Give it more air.

Keep in mind that basic control of a stove is controlled by the alogrithms contained in the intergreated circuits on your control board and they don't always provide the perfect a/f ratio, especially in the lower heat ranges so you need to add a bit of air to 'lean' out the a/f ratio and achieve a complete burn.

Thank you for that complete answer - it helps a lot. Sometimes people use terms that they think are clear, but to simple people like me that have no knowledge of things such as engines, are murky at best.

 

[SidecarFlip]

No problem. It won't always burn optimally simply because it would take continuous adjustment, something your control board 'attempts' to do across the heat ranges but the board's 'intellegence' is goverened by programmed in parameters so you have to make fine adjustments with your manual draft controls.

FYI. my viewing window is sooty right now, the backer board is black as well but when the outside temperature drops (and it will, it's winter afterall), the t'stat in the kitchen will sense a temperature drop, it will close the control circuit on the stove, the stove will ramp up, get hot and burn off the soot....and I'll see the flames again

I've been idling for a couple days now on low heat output. I don't look at it as an issue, more like being frugal with fuel. This whole alternative fuel thing is about being frugal IMO.

 

[Bank]

I'm having the same issue with my Harman Accentra. The ash builds up pretty good on the front of the burn pot and the flame hits the glass. As long as I keep cleaning that inch to inch and a half of ash off the front of the burn pot the glass stays clean. However, if I'm gone for over 5 hours I come back and it's dirty. I usually take a dry paper towel and just wipe the soot off the glass.

Note sure what else I can do, I clean it once a week and take the plate off once a month and clean out the exhaust and vacuum out the fan, not sure how to control the "richness" though. Any thoughts would be great.

 

[John Fortier]

Thanks all for the help and new knowledge I have locked away in my head...just hope I remember where I put the key.

 

[SidecarFlip]

I'm having the same issue with my Harman Accentra. The ash builds up pretty good on the front of the burn pot and the flame hits the glass. As long as I keep cleaning that inch to inch and a half of ash off the front of the burn pot the glass stays clean. However, if I'm gone for over 5 hours I come back and it's dirty. I usually take a dry paper towel and just wipe the soot off the glass.

Note sure what else I can do, I clean it once a week and take the plate off once a month and clean out the exhaust and vacuum out the fan, not sure how to control the "richness" though. Any thoughts would be great.

I can't speak with knowledge about a Harman because I don't own one and their operation is not like other stoves, but Bioburner can. shoot him a PM. I'm sure he can help you....

 

[John Fortier]

Changed air intake and all is good.

 

[SidecarFlip]

Changed air intake and all is good.

I like posts on issues that have happy endings.

Mine is pretty sooted up (I just glanced over at it).... but it really hasn't ramped up but once today. That will change tonite I suspect. Supposed to drop into the upper 20's here later. She will ramp up as the heat demand increases and burn off the crap on the window. Mine has to run hard for a time before it's hot enough inside the firebox to 'clean' the soot off.

First couple years I ran on the stove controls, then added the remote t'stat. That changed the way the stove ran and stabilized the temperature swings too. Best 20 bucks I have spent in a long time.....