Things You See at Night

[SeanD]

So I boiled inside at night for the first time tonight. I've got a shack now and it was a pretty nice feeling having dry clothes on a raw, wet night. I'm still with you in spirit backyarders!

But I did see some things I hadn't seen before. First off, my stack was like a Roman candle the way sparks were flying out. At one point it even looked like a red version of a propane torch with a cone of not-quite-flame, but heat jetting out. I'm loving the draft and the clean hot burn, but is this too dangerous?

Second, the elbow coming out of the back of the arch was glowing cherry red for the first three minutes between firings.

I only boiled for two hours. Would things worsen in a longer boil? Should I do something about these issues immediately or is it pretty normal?

Thanks,
Sean

[PerryW]

it is normal. I end up with the snow around the sugarhouse covered with pieces of black charcoal.

You can try closing off the damper some to reduce the flames shooting out of the top of your stack.

[brookledge]

Sean
It is normal for sparks to come out and for your stack to get real hot. Boiling in daylight it is less noticeable but it is still there. The key to being safe is to monitor the areas around the stack and outside to make sure you don't start a fire. I remember a sugarhouse about 20 miles away from me that put in a new arch that uses forced draft. Well it wasn'tlong before the cedar shingle roof was on fire. They were able to put it out with out any major problems. They then put on a metal roof
Normal stack temps for wood burning are anywhere from 1200-1700. So without the proper clearence it can ignite your sugarhouse
Also many times when the unburnt gases exit the stack they will ignite and it will look like torch like you said.
Keith

[northwoods_forestry]

Stack temps of 1200 - 1700 seem pretty high and I don't think shooting flames out the top of the stack is a good idea.

The Leader technicians recommend keeping the stack between 750 and 850 for woodburners and between 850 and 950 if you have forced draft.

My 30" x 8' hums along nicely at 1000, but beyond that things get dicey.

[Clan Delaney]

I haven't had a problem with my stack turning red, but the sparks are a problem. I have a separate timer I use to remind myself to step outside and check the ground. Lots of dry leaves here...

[SilverLeaf]

Sean
The key to being safe is to monitor the areas around the stack and outside to make sure you don't start a fire.

What's a safe clearance? I'll be boiling outside this year on my new 2x6. I was going to set it right next to my garage, thinking it would help block the wind. But now I'm wondering.... would I be better off with a 10 foot buffer? or even more than 10?

[Clan Delaney]

What's a safe clearance? I'll be boiling outside this year on my new 2x6. I was going to set it right next to my garage, thinking it would help block the wind. But now I'm wondering.... would I be better off with a 10 foot buffer? or even more than 10?

My stack is only 18" from the outside of the shack, but comes to withing 10 inches at the peak. No issues. The wall is warm, but hardly combustible. Then again, as I said, my stack doesn't glow.

[Brent]

stack temps of 1700

that puts you in two categories

1) too much wood

2) not enough insurance

============
seriously though that is sending one aweful lot of wasted heat up the stack, not to mention the melt down / fire risk

[SeanD]

I'm good on official/legal clearances and I have a metal roof, but there is a big pine near the shack that I worry about. Last night was very damp, so I felt a little safer.

Maybe I'll back off on the wood. I have to admit, it's addictive to finally have a clean, hot burn. For years my fires choked themselves off. With my new grate and stack everything is GONE in 5 minutes. I'm throwing stuff in there that I would never have thought small enough before.

I'm not going to do any major mods this season because I'll be lucky for another boil, but next year I'll probably add a damper and an ash door that I can open and close. I'm still on a block arch and I'll probably keep these dimensions for my "real" arch because they are so successful.

I remember there once was talk of people peppering the top of their stack with holes as a homemade spark arrester, but I don't remember if the consensus was a good idea or not. I'll try to search some old posts.

Thanks,
Sean

[maple flats]

1700 is way out of line. I used to run at 700-850 for non forced draft, now I have high pressure air both under and over the fire. I now get 700-900 stack temps (my thermometer has a probe right into the stack) but wow, that boil is way hotter. I used to get a ball of flame at the top of the stack (this was unburned wood gas getting some oxygen) Now I no flame at the top and I see no sparks. I am truly impressed with my new draft set up. I used a report for the Vermont Maple Research Center, followed their report and WOW. I now get 20 minute burn cycles where I used to get 5 minutes. I am using about 30-35% less wood and the boil is fantastic. I have checked the stack after dark and see total darkness with this new set up. I get full fast boil in every area of both pans, much better than ever before. When I add wood I add about 2-2.5 as much as I used to at a time but I never shut the blower down and within less than a minute of adding I again have full fast boil. This has surpassed my wildest dreams.
As for your spark out the top, be careful, that can be dangerous. Watch for dry leaves, roof shingles, and anything combustable. What kind of wood are you burning? I used to get a little spark action if I put in some pine and a few other kinds but I never got very much. Try to get more air to it to burn everything under the pans and not up the stack.
Good luck.

I wonder if my new set up might possibly be closer to an inferno or some other more modern higher effieiency design?

[vtsnowedin]

I wouldn't worry too much about a few sparks that are visible at night that burn out and disappear as the smoke is still rising away from the stack. They are just part of burning soft wood. What is a real concern is if your stack is ejecting burning embers, as in small fragments of burning wood that are solid enough to reach the ground while still burning. Things that will create this problem include green softwood, too small a stack, too short a stack, and too large a blower.
My 3x8 has a fourteen inch stack that ends twenty one feet above the floor and six feet above the metal roof. The wood saver blower fits it and I get no rocket flame at the stack top and no large pieces of soot or cinders on the snow around the sugar house. I'll still check it very close after the snow is gone and the old grass around the sugar house gets dried out by the spring winds. The road running above it does make a very good fire break but if a fire got across that it's a long way to the top of the slope.

[northwoods_forestry]

Maple Flats - Do you have a link to that report from the Vermont Maple Research Center you mention? It sounds like we are running pretty mush the same with the only big difference being the firing rate.

I'm firing every 5 minutes with mostly hardwood to maintain a stack temp of 900 +/-. I run the forced draft at 3/4 and don't have to back off to fire. At full throttle on the draft I start blowing sparks and embers out the doors even when they are shut (not air tight). For a while I ran the draft at full and leaned an insulated panel against the doors between firings. But I wasn't happy with how this heated the front pan and it was a pain in the butt. Now that I've backed off on the draft I get a better boil in the front and I don't have to mess with taking the insulated panel on and off. I'm still getting very complete combustion, little ash, no smoke and only a few sparks out of the stack. I've burned through about 1 1/4 cords so far to make 28 gallons of syrup from sap at 2% or less sugar.

[kytepc]

You can never be to careful! The end of Feb a partner and myself decided to get a container and move inside to do the back yard production out of the weather. We decided to keep way 300ft from any building due to any fires that could happen. The snow was removed and the pasture field grass around where the box sits. We have been boiling on and off for the last 2 weeks with slow production this year, the snow has given way to warmer weather. 2 days ago I collected my pails, parked the garden tractor left it running (big mistake) unloading the sap pails into the box, it took a min to run the sap through my prefilter on my way back out of the box I saw smoke.
The tractor was still running with fire below it and spreading fast! I quickly got it out of danger, the only tool I had was a round mouth shovel to attack the flames but there was too much breeze and the ground was too dry, it spread out of control fast! I phoned the FD they were there in no time took them 3 hrs to get it out with a crew of 8-10 and 3 trucks. I don't know how the fire started other than a spark from the exhaust on the tractor, I was not boiling at that time. This summer I am going to bushhog and keep the grass short 200 ft around the shack! In the plans I will have a portable pump and a container of water, just in case anything would happen.

[mapleman3]

Maple Flats, if you come across that report I would love to read it, I too am running a 3x8 raised and fire every 7 min. 20 min burn time would be sweet!!

[Brent]

Jim
check out the thread I started "Simple Air Injection"

yesterday was 23 minutes between firings on a little 2 x 6 rig.