Arch performance : not running very hot

[smokeyamber]

Ok, so I have a 2x5 arch, homemade, the back ramp goes down to around 2-3 inches and the stack is 8" but goes out and then takes a left turn and outside the shack into a upright stack that is around 12ft high. I run a blower under the fire and fired with dry pine and some small hardwood. With this combo I could not get a raging boil all season. To be sure it was a good boil with the new Smokey Lake pan and float box, but not raging. I may have averaged 10 gallons an hour... though likely it was less. Stack temps were in the 400 range most times, with the only killer temps when the creosote fired off. Not sure now if it's the arch or the stack. I can add more stack , but wonder if the real issue is the way the pipe comes out and goes horizontal for about 4ft and then up into the stack.

In the past the ramp had a larger space and I had even less boil in the back.

I am debating modifying the shack to run a stack straight up and maybe going from 8 to 10" inches ... any opinions on that setup ?

[n8hutch]

If you just have a flat 2x5 pan with dividers & no flues I don't know if you are going to do a lot better than 10 gph. A straight stack would be better for sure. Maybe 1" , to 1-1/2 air space under pans. You really only need the volume of your smoke stack.stack volume is roughly 25 cubic inches per inch of stack so if you have a 2ft wide arch that is pretty close to a 1" air gap.

[Super Sapper]

An 8 inch stack will give you around 50 square inches so that is what is needed under your pan for draft. How many cfm is your blower? I think a 2 X 6 needs about 250 cfm. It sounds like you are not getting enough air if you do not have the heat at the pans or going out the stack.

[n8hutch]

Super sapper you are correct. I goofed on my math, still you could close it down to 2"

[brass maple]

I agree with super sapper. Your just not getting the heat. I use a 18" x 36" and get that much at least 8 to 10 gph. Is your blower just blowing in threw draft dor or plumbed in to go up through the fire grates

[maple flats]

If you get any creosote you are not firing it hot enough. Creosote only forms when a fire is starved for oxygen. The stack temp should never be that low unless you just started the fire, or you have a very high tech. air over fire system. Being your first year, I doubt that's the case. Open it up and make it burn hard. You need a blower in the 200-250 CFM range, and you must fuel every 7-8 minutes. Each time just add wood on 1/2 of the firebox, 7 minutes later, add to the other and repeat every 7 (or 8) minutes.

[smokeyamber]

Thanks everyone for the feedback on the boiling, I run a blower , it is from a old JenAir range and I actually throttle it quite a bit to keep the ash down, it is directed in from the back and goes under the grates. I previously had it going into a crimped pipe that had holes to direct air up into the fire, but this year went more wide open. I do fire every 7 min... I kid folks my life is lived in 7 min increments during sugaring season :lol: Wood this year was nice and dry and small.

So should I plumb the air into piping to direct it under the grates more ? I could build a distribution manifold as well, should it come up from below ? I could make it come in from the sides as well if that would help.

Also how much would a preheater give me on increasing boil rate. I know I am not going to get amazing rates on this setup, but goal is to hit a consistent 10 gallon per hour and I don't think I am there yet.

Is increasing the stack to say a 10inch pipe and going straight up and out a big aid in draft / burn rate ( assuming the blower is going ). I assume the space under would increase a bit with this change as well.

One other factor that I was wondering about is sap depth, this year I was conservative around 1 1/2" , how much would dropping to say 1" help and what are the things to watch out for with this low a depth ?

One thing I loved about this year was the new Smokey Lake 2x5 and the float box was awesome... first year not bucketing everything into the preheater;)

[Super Sapper]

You need more air for the fire. If by keeping the ash down means not blowing in out the door or cracks then you need to make it more air tight or improve your draft. Going straight up will help and going 10 inch may help but 8 inch should be plenty. Too many coals will also starve it for air by blocking the grates, I have also noticed that you need to spread out your coals evenly or the air will go around the wood and reduce the boil.

[smokeyamber]

Thanks supper sapper, I do find that the grates are getting covered. Most arches I have seen have pretty small grates, but I may rework them to be more open for next season and the whole arch front could be re-done as well. Currently it's still mostly a "dryerator" and the door did not seal as well as I would have liked this year. I could also run some air into the fire from the sides pretty easily, not high pressure like AOF more like AOF lite..:lol:

Now if I got started on all this now I might even be ready before the sap flows next year :o

A preheater and hood may be in the cards, though I would like to just cover the first two channes and leave the front open so I can keep an eye on stuff. Anyone ever build the hood to be easily raised ? Like on a pully system ?

Thanks again for the great feedback !

[maple flats]

My AUF just goes into a 4" stove pipe laid flat under the grates with the end capped about 6" from the front, and it has 3 rows of holes every 3-4", one row each facing straight up, and one each facing towards the outer edge of the grates. My front is not air tight, it has a space about 1/4" between the 2 doors and I get no ash or sparks or smoke out the front. I light the fire by holding the weed burner pointed above the wood until I see the fine ash in the firebox being drawn into the stove, (I have then established the draft), then I hold that torch aimed at the base of my fire layup (I place 1 bigger piece down each side, then I fill one row of wrist size wood across that, and finally I place more crossways to the second row). I generally hold the big torch aimed at the base of the wood for 2-3 minutes, until it is fully involved. Then I turn off the torch, turn on the blower and the blower remain on until maybe 45-60 minutes after my last fueling. As I said in my earlier post, if you are getting creosote you are not burning hot enough, you must have more air. Before I had a blower, I propped up my draft door wide open (about 14" x 6") to get the fire as hot as possible, now with my blower it gets even hotter. Get as much air in as you can and have no damper in the stack to restrict the flow. This is not like a wood stove heating your home.