Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers WITH EPA-Certified Models => Portage & Main => Topic started by: jreimer on December 10, 2013, 07:43:19 AM
-
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?
-
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.
-
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?
-
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?
-
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.
-
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.
-
I would agree with coolidge, Elm is great firewood if it's dry but it does hold a lot of moisture
-
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.
-
Are you still burning the Elm? What is your water temp set at?
-
Yup. Still burning the elm because that's the only thing I have dry enough right now. Temp is 175 on, 185 off.
-
Here are pictures of the hard ash chunks. These were just pulled out from around the nozzle.
[attachment deleted by admin for space issues]
-
Throw in some unseasoned stuff if you have it to see if you get the same chunks. What are your air settings at?
-
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.
-
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.
-
Is that stuff hard like lava, if so it very well may be from dirt on the bark.
-
It's not really that hard. I can crush it in my hand then it turns to powder. It is hard enough to plug the nozzle though. This morning I took my cleanout shovel and scooped out the hard ring of ash from around the nozzle again. It forms every load as a doughnut around the nozzle. I'm using the same wood I used all of last year and never experienced this before. Very strange indeed.
Thinking of the wood, I am burning a lot of medium sized unsplit sticks that have the bark on them, so perhaps I could be burning more bark than usual. The wood is clean and not dirty. Perhaps there is something strange in the elm bark that is causing this? But why only around the nozzle?
-
Are all the air holes clear in the firebox, I believe there are 13 of them. If so try giving the fire box air a little more, maybe out 6 turns.
-
I'm curious, do you have the ability to try some different wood?
-
Ok, so I did my weekly cleaning last night. Nearly 8 gallons of ashes!! I'm going to experiment with a lot higher airflow settings with the same wood and let you know how it goes.
-
How did you make out with your air flow settings?
-
Sorry I haven't posted for awhile. Been busy with family, Christmas, New Years and fighting the COLD!!! Man it's been cold here and the wood has been flying through the furnace. Highs of -15F and lows of -35F for weeks with some -40F's thrown in there for fun.
Anyway, the higher air flows haven't changed the crusty ash issue. In about a week I will have run out of elm and will be using ash. I'll see if that makes any difference.
-
You might want to turn the air back a bit if you start getting 1/2 inch or larger pieces of carbon on the shelf above the vertical tubes
-
So it looks like the culprit is the elm that I have been burning. I have switched over to the ash portion of the woodpile and this hard crusted ashes phenomenon appears to be nearly eliminated.
Posts on some other forums seems to support this as well, as others have reported the same hard ash chunks when burning elm at high temperatures. This would explain why it was only forming around the nozzle as that is the hottest section of the firebox.
A chemical mystery with elm I suppose...
-
Depending on the species of elm I've had a few amishmen tell me that elm collects calcium out of the soil more so than other trees. A really good hard elm thats dry seems to dull a chain faster than other woods. Your chunks of hard ash could have some calcium mixed in the ash and fire baked so it would get hard.
-
Well the elm problem hit me again last night. I have been mixing in a few elm splits over the past few days that were mixed in with my spruce pile. This morning I go out to fill the stove and it's at 108 degrees. Half a load of wood left and smoking like crazy.
The ashes had crusted around the nozzle enough to partially plug it up. Very frustrating when it's -24 Fahrenheit at night! This hasn't happened in 2 years since I stopped burning the elm. Anyone else experience this with a certain species of wood?
-
Interesting, I’ve been eyeing several dead elm, I’ll cut em up and burn nothing but elm for a few days and see what the G400 does with it.
-
I really don't think this problem is a wood species problem at all. I've burned a crap ton of dead Elm in my stove and I've not noticed my boiler behaving any differently than with any other species.
My nozzle used to partially plug once or twice a year as described, but I've always attributed it to dirty wood(think "muck" from the woods).
I take the hoe that came with my boiler and poke it's opposite end through the nozzle and make sure it is thoroughly clean at least once a day now. Problem solved.
I know the folks at P&M don't want us poking anything through the nozzle, but I don't really care.
I use nozzles made by KarlK, and they last almost twice as long as the ones from P&M. They aren't nearly as susceptible to damage.