2x6 drop flue arch build

[Hkb82]

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Had a 2x4 flat pan oil tank build but was time for an upgrade. Just converted it to accommodate the 2x6 set of pans made.
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Made the stack 8 inch plus added auf blower port on the back side of the arch and plumbed into the bottom of the ash compartment as most do. This thing is air tight plus k wool and fire bricked. Plans are to build a new sugar shack and arch in the next year or two so I just needed it to work for a few years. Seems like it will be a great upgrade from last year. I did a heavy VVVVV grate pattern plus filled in the V sections with some refractory cast to help protect it. Any guesses on boil rates. I usually get it to the 5% using ro then fill the head tank and boil.

[Hkb82]

Sorry o give up trying to post pics on this site.

[darkmachine]

We did a 2x6 build to fit a set of pans 2 years ago and it's been great. with the forced air we get in the 40's for gph. I burn dry oak sawmill slab/sticks. I feed it every 5 minutes by the clock literally, we have a timer in the shack. You can really push it. with our RO I have no problem getting through 200-400 gallons of sap between school bus runs(5hrs) during the day. I really like the maple leaf on your door. I wanted to do something fancy on ours but the door hardware I got pretty much covers the whole door.

[Hkb82]

Thanks and good to hear. I am hoping for the 35-40gph after my ro this year. 22714
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[Hkb82]

Got my first boil in yesterday and was pretty pleased with the outcome. I was running non ro straight sap and 2.5-3%. Managed to boil around 200gal in 8 hrs so was around the 25gph. I was loading every 8 min and it seemed to be good for the wood I was burning. A mix of mostly hard wood wrist size. Being my first boil I ran the pans around the two inch level for half the day then I dropped it to about 1.5 once my confidence built lol. Ran my ro all day so it’s time to start boiling concentrate.

[mol1jb]

Looks good. After you get more comfortable, continue to lower the pan level in the flue pan. You will get the best boil rate with 1/2 inch sap over the flues. Some have even less but that makes me uncomfortable. Also I would decrease the space under your flue pan inside the evap. You want to force the hot air through the flues as best you can. You can build the evap base under the flues with sand, bricks, or ceramic insulation to just below the flues (no more than 1/2inch gap). This will also help improve your boil rate.

[Hkb82]

Thanks I did another boil on it today. Ran it at 1” for most the day and to the best I could figure was boiling around 30-35gph when firing every 7 min.

Not sure about running less then 1/2 inch above my flues. it’s a drop flue and that would put less then 1/2 inch also in my syrup pan up front. In your raised flue I can see that being doable with the two float boxes. I did try it at close to the half inch mark maybe a bit more above the flue pan. Was finding it didn’t have enough flow when drawing off to run smoothly. Temps would climb during the draw past what I’d like. The 1 inch mark seemed to fun perfectly for me today. Had a raging boil across the entire rig including the cold sap entry.

As far as the space between flues and arch it slopes up to 1/4 inch gap at the back right before it enters the stack. Should I have made it 1/4 all the way across the flues??

[Pdiamond]

I don't think you would need to close it off that much 3/4 to 1/2" is good.

[Bricklayer]

I find that I usually get the best results with 1” depth in our drop flue. Keeps everything running smooth. I’ve gotten brave a couple times and ran it really low. You get amazing boil rates and the draw offs come off a lot faster. But Dosnt leave much room for error. There is usually a little bit of lag in between the levels as well untill the float box catches up. So I like to stick with 1”.

[Hkb82]

I was drawing off ever 10-15 min. Funny thing is it would almost always be drawing off when my wood timer would go off. I allow it to finish drawing off before I refill the firebox. I load it as close to the pans as I can get it so I just let it finish drawing off then refill the wood.

As for gap under flue pan maybe I will slide some half bricks under it to see if it changes anything. Don’t think the sand will work in my setup as I’m running a pretty strong blower and during cleaning I’d definitely push it around. As I mentioned it’s almost sitting on the ramp at the back. Like 1/4 inch gap. The ramp runs 3” gap at the front to 1/4” back. I was gonna run it tighter but though it looked almost flat @ 1.5” to 1/4”. Most the professional rigs look to have more slope then that. Sliding a couple half in is worth a try though. Anybody else with some input on this???

I think the next thing to do to up my boil is to pre heat the sap coming into the flue. (Hood and preheater don’t tell my wife lol).