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[jreimer]

I get ash baked to the inside tapered ends of my nozzle that really builds up.  I have to scrape it off down to the refractory every week or it doesn't gasify as well.  Anyone else have trouble with ash baking to their nozzle and plugging it up?

[slimjim]

Don't scrape it, reduce the amount of ash in the burn chamber to less than 3 inches deep, it will burn the coals to ash and blow itself clean, don't overload the stove as well, it creates more coals than needed if overloaded, 3 inches of coals and ash.

[jreimer]

I clean out my firebox every week and don't have more than 3 or 4" of ash and coals in the stove.  It just seems in the process of blowing the fine ash through the nozzle some of it sticks to the front and back tapered sides and slowly builds up.  It's very fine ash that's baked on there hard enough that I have to scrape it off.  It certainly won't blow out on it's own.  FYI I am burning elm firewood.  Is it the type of wood that I am burning that could be causing this?  Perhaps the moisture levels are a little high?  Anyone else experience something similar?

[slimjim]

Elm does have a very high moisture content and the ash sticking in the nozzle is more than likely due to moisture. couple of questions, Do you see pieces of black carbon 1/2 inch or larger on the shelf at the top of your vertical tubes and how much air are you giving it on the damper plate that is mounted to the blower motor?

[jreimer]

I get a few small flakes of carbon on the shelf above the vertical tubes but nothing as big as 1/2".  I have the damper plate set around 1/4" as per P&M's specifications.

I also get an inverted cone of hard ash in the secondary chamber right below the nozzle that I almost have to chip off of the refractory brick during cleaning.

[coolidge]

I do get the inverted cone, but nothing like what you have. Just fine ash that can be pulled out. Try some different wood if you have some.

[slimjim]

I would agree with coolidge, Elm is great firewood if it's dry but it does hold a lot of moisture

[jreimer]

Well it happened to me again last night.  Went to fill the furnace this morning and the water temp was down to 112!  Checked the stack temp and it was 120.  Opened the door and there was half a load of wood sort of glowing/burning. There was a high demand for heat overnight, so it wasn't sitting and idling.  Dug down to the nozzle and it was almost plugged with a hard layer of ash on top, about 2 inches thick.  The hardened ash sort of looks like brownish Styrofoam.  I'm not sure what's going on with my wood this year!  Is high moisture "cementing" my ash together?  I wouldn't think that the temperatures at the nozzle would allow any moisture to condense there.

I'll post some pics of the ash when I have a chance.  Perhaps collective minds can figure out what's going on.

[coolidge]

Are you still burning the Elm?  What is your water temp set at?

[jreimer]

Yup.  Still burning the elm because that's the only thing I have dry enough right now.  Temp is 175 on, 185 off.

[jreimer]

Here are pictures of the hard ash chunks.  These were just pulled out from around the nozzle.

[attachment deleted by admin for space issues]

[coolidge]

Throw in some unseasoned stuff if you have it to see if you get the same chunks. What are your air settings at?

[jreimer]

Air settings are at factory specs.  Upper is 4 turns, lower is 4 turns, blower damper is 1/4" inch.  I only get this hard ash layer forming right around the nozzle opening.  The rest of the ash stays fluffy and loose.

[coolidge]

That's weird, never seen anything like that. I would still try a couple loads of semi seasoned if you have some, need to start eliminating possibilities. Even wet wood, the boiler will burn it with a good bed of coals.

[slimjim]

Is  that stuff hard like lava, if so it very well may be from dirt on the bark.