Black glass

[tyler walker]

I first mentioned this in my post "what to do with moist pellets", but it seems to warrant it's own thread.
I've switched to Somerset pellets, and the stove is running wonderfully. However, even with Somersets, I still get a thick band of opaque build-up on the top 4" of the glass after about 12 hours of running. It starts with a haze after as soon as 15 minutes, then slowly builds up to thick and black. This band has appeared with all 4 brands of pellets I've tried so far. Someone had mentioned that if this was happening with all brands of pellets, then there is a problem with my stove. I have no problem getting the glass clean. The shop vac with brush attachment takes 99% of it off. I use stove glass cleaner only when a wet paper towel can't get the last bit. The manual mentions that the glass needs to be cleaned every day. Could it be that this is just the way it is with this stove? If not, what can I try?

 

[DAKSY]

Can you add more air to the mix? My feeble automotive brain is telling me that black is caused by too rich of a mixture...thin it out by adding air...YMMV

 

[will711]

What Bob said sounds like incomplete combustion add air if your stove has those adjustments.

 

[tyler walker]

I can try that. I have my combustion blower at the factory setting (3 of 5), but I can notch it up and see if there's an improvement.

 

[SteveB]

Can you add more air to the mix? My feeble automotive brain is telling me that black is caused by too rich of a mixture...thin it out by adding air...YMMV

+1
Tyler,
I've had the same problem in the past with my King stove. It was caused by a rich mixture (too much fuel or not enough air, whichever way you prefer to look at it). Do you have a damper or adjustments on your controller? Of course it can be caused by a partially plugged exhaust too. I had air leaks around ash pan slides and a bad door gasket which caused less air flow through the burn pot. I now get a thin brown film after a while because my stove has no air wash, not the thick black crap I used to get. Somersets are good pellets, I don't think that would be the problem.

*Edit: Didn't see the last two posts while I was typing.

 

[kinsmanstoves]

I would check for air leaks first. or a blocked/clogged exhaust or air chamber. Napoleons are known for such a problem.

Eric

 

[tyler walker]

I adjusted the combustion blower setting. It looks like I may have been at 4 of 5. Now I'm at 5 of 5. It's hard to tell what level I was actually at as all the settings on the stove share one meter that only switches from displaying heat setting when you adjust them. I'll clean the glass today and report back tomorrow. Thanks for all the tips. My auger feed rate is trimmed to 2 of 5. Perhaps I can try slowing that down one more notch as well if the added air doesn't do the trick.

 

[Boondoggie]

I have the exact same on my NPI40. I can reduce the buildup on the glass by increasing the air to 5 (so it takes 2-3 days to build up, not less than a day), but my fire gets really small and "blowtorchy" and I don't seem to get as much heat.

 

[stoveguy2esw]

typical of a "rich" burn, fuel air balance is skewed toward the fuel. literally all of the advice above is worth trying. what we have is either a leak , door window ash drawer etc burn pot maybe not seated squarely allowing air to get past it instead of through it, high EVL is a possiblity dont know thge hookup you are using so we might come back to that.

do "dollar bill" test for door and ash drawer if possible , if not use smoke or a match flame tracing around each gasket with stove running to see if we are sucking air (do this before it lights as the glass is known to get pretty dang hot) if the stove is equipped with an "airwash" system, check the air supply for it for blockage or restriction.

 

[tyler walker]

i'm going to try inspecting the exhaust system today and looking for leaks as well. today is much warmer than yesterday, so i can afford the down time. the instructional video mentions that i should discard the exhaust blower gasket and replace it whenever I inspect it (at least that's how i'm understanding this). obviously, i don't have a new gasket handy. do i need to worry about this?
skip to 7:51. (i couldn't figure out how to link to the time in the embed)

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[tyler walker]

yesterday i gave the stove a full "end of season" cleaning. i didn't find any terrifying blockages, but there was a fair bit of buildup in the exhaust system. unfortunately the glass still blacked up in under 24 hours. i think it's burning a little hotter, and the buildup is less than before. any increase in efficiency is good, i suppose. since my stove is fairly new, i've called in my installers to have a look to check for leaks or anything i might have missed. they'll be here some time after the holidays. to be continued. merry christmas, pellet friends.