2x4 raised flue operating questions

[ebliese]

So we've got new pans this year, Smoky Lake raised flue on our 2x4 Corsair arch. For those of you who run this rig, or something similar, a couple of questions come to mind.

One-when shutting down, how much sap do you have in your head tank to flood the pans with? With our old divided pan we would stop firing at a certain point and then flood the pan, bringing everything to a boil to sterilize it. Thinking of doing the same this year but obviously the boil rate of the raised flue is much higher than our divided pan.

Two-at what point do you open the ball valve on the transfer pipe from the transfer float box to the front pan when you start your boil? I would presume this ball valve gets shut at some point in the shut down process to help preserve the gradient. If so, then when is the valve opened upon starting the boil?

I recognize everyone's practice is a little different but some general ideas would be helpful. Oh, and yes, the pans have sight glasses.

[Pdiamond]

Daniel, I shut down when I am tired, being retired i can boil all day if needed. When I have about 25 gallons in the head tank. I do not flood the pans. I just leave the float valves open as normal and let the fire die and don't turn the blower off until there are zero coals. Once the temp get down to 180 on the auto draw off temp gauge for the front pan, I shut the blower off and know I can leave the pans for the night. I double check the fire box. I do not close anything off between the front and rear pan. I have never had any problem with preserving the gradient. It stays in the front pan for me.

[wnybassman]

On my 18x60 raised flue I flood rear pan when I have 2 1/2 to 3 gallons left in the head tank. But prior to that, at about 7 or 8 gallons left I switch over to burning pine only to reduce coals. I mix in pine the whole boil so I can control coal load. After I flood the flu pan, I toss in a big handful of VERY finely split pine. This will create an intense fire to get everything to a boil, but will turn to ash in minutes.

Obviously, your rig has a higher GPH so your numbers will be different. Just gonna have to play with it until you slip into a routine.

[gbeneke]

Great answers already. I raise my flue pan level to 3 inches from my operating height of 1 1/2”. I leave the flue to syrup pan open. Also, after the fire is nearly our and fanoff, I open the door a1/2 inch and leave it open. That prevents the door insulation from sticking to the door the next morning.