2x4 Smoky Lake High Output Low Boil

[skinny78]

I have upgraded my half pint to a Smoky Lake High Output 2x4 raised flue pan set and I have yet to get a full boil in the flue pan. I lengthened the arch and changed the flue location from the back to the top like most evaporators. It now has 16' of 8" flue pipe and I am not running a blower. I started with a wall under the flue section to direct the flue gasses up through the flue pan and was getting a very distinct boil line across the flue pan so I have started tearing it out and experimenting with brick in that area. The best evaporation rate I have got is between 20 and 25 gph. Jim rates this pan set at 30gph without a blower. I have a digital stack thermometer and I can get temps up to 1300deg. Is there anybody else running this pan set? How is the boil and evaporation rate? What should the firebox look like on a raised flue rig?

90639064

[mellondome]

How deep are you running the sap above the flues? You will want to be no deeper than 3/4 -1 inch. The shallower you run the pan, the faster it will boil

You will also want the area under the flue built up to within 1/2 inch of the flues... to force the heat up in. With an area at the very back of it (say 4 " with your pan size) for the gases to drop back out and go up the stack.

Make your wood no bigger than your wrist.

[skinny78]

I try to run the flue pan at 1/2" and the front pan around 1". I currently have a wall one brick deep up to 1" from the bottom of the flues and it is boiling vigorously right there. Wood is very good and split small.

[jmayerl]

Your stack is most Likely WAY to long. 16' is what is needed to put draft through a 8' long arch.

[mellondome]

Try closing up the space under the flues to almost touching. Also, build up the area under the stack to help restrict the airflow/draft. You are probably sucking the heat past the pan so fast it isnt heating the pan good. I fought the same issue with my 2x6 for the first couple years I had it.

[Flat Lander Sugaring]

CERAMIC BLANKET 2"ALL AROUND, bricks are not insulation

[skinny78]

Thanks everyone, I made a wall under the flue pan that was 12" deep and all the way up to within 7/8" of the flues. The top layer is insulation board and it is near the rear of the flue pan. Boiled 100 gallons last night at 30gph. If you want more evaporation insulate under your flue pan!

[Flat Lander Sugaring]

Thanks everyone, I made a wall under the flue pan that was 12" deep and all the way up to within 7/8" of the flues. The top layer is insulation board and it is near the rear of the flue pan. Boiled 100 gallons last night at 30gph. If you want more evaporation insulate under your flue pan!
2" entire arch 3" in some area. Insulation will make a huge difference and board is better than ceramic blanket.

[Sugarmaker]

Sounds to me like you have the geometry of the arch closer to what it should be that may be what made the most difference.
7/8 to 1/2 inch from the flues sounds much better. The ramp needs to be directing heat from the fire box up into the raised flues. watch the area entering and leaving the flue area. I believe it should be close to the same area as the stack. That should allow good draft through the system. My 2 cents.
Is that a round steel sugarhouse? Very unique! I like it!
Regards,
Chris

[Josh Nickles]

Thanks everyone, I made a wall under the flue pan that was 12" deep and all the way up to within 7/8" of the flues. The top layer is insulation board and it is near the rear of the flue pan. Boiled 100 gallons last night at 30gph. If you want more evaporation insulate under your flue pan!

Wow! 30gph with a 2'x4'!? You have one hot rod rig there!! Sounds like a nice set up. Yeah, cool looking building too! Is the season still holding on down there?

[skinny78]

Our season is over. We made 79 gallons of syrup this year, our best year yet! The new sugar house is an 18' aluminum grain bin, it is 5 rings high making the wall height around 13'. It has worked very well and I don't think I will need a steam hood. I will be building an RO for next year!