Shutting down the drop flue at the end of the night.

[bryankloos]

Hey guys.

First boil has been going well and the pan is getting close to sweet.
That said, as I’m sitting here watching the rig rip, I realized I didn’t have a shutdown procedure in mind.

So, how do you all shut down at the end of a boil?

I have a mason 2x4 drop flue with float valves for both the flue pan and the syrup pan.

Thanks!!

[tcross]

while i don't have a drop flue (i have a raised flue 2.5x8) i assume the procedure would be very similar especially since you have a cold and hot float box. what i do at the end of the boil is this... once i'm at the point where i'm about out of sap, i'll pull a couple of gallons of sweet from the draw off valve. you'd take less out because your rig is smaller. i usually run it through a filter and into a stainless bucket. then i'll let a little extra sap into the syrup pan from the flue pan. probably about 1 3/4" to 2" in the pan. plug the wholes between the partitions, then, i put the rest of my sap into the flue pan (also drain my preheater into the flue pan) and get everything to a good boil and shut it down. you need some extra sap in the syrup pan and flue pan because it will continue to evaporate after you stop fueling it. on your next boil you'll basically reverse the process. Fire the evaporator up, then once the syrup pan starts boiling, unplug the partition holes and add the sweet i took out when shutting down, back into the front of the syrup pan and then open the valve up from the cold float box to the feed tank and away you go. That is more or less how i do it.

[Andy VT]

Side note, is it common for a drop flue to have 2 float boxes? What would be the reason, and how is it even possible? Is the flue pan elevated in some way?

[Pdiamond]

one would be incoming sap and one would be out going to the syrup pan

[Super Sapper]

Typically you would not have 2 float boxes for a drop flue setup. You would have one for the flue pan and it would regulate the level in both pans unless the flue pan was higher than the syrup pan, which is not a normal setup.

[Andy VT]

Typically you would not have 2 float boxes for a drop flue setup. You would have one for the flue pan and it would regulate the level in both pans unless the flue pan was higher than the syrup pan, which is not a normal setup.

Yeah, this is what made me ask. I'm having trouble picturing the setup. How do you get the drop flue pan up higher than the syrup pan and why would you go to that trouble?

[bryankloos]

... Should have written raised flue... My bad. Sorry guys.

[Andy VT]

Sorry, after that last post I was like, oh, maybe all this fuss over a typo! Sorry about that!
Well, hopefully by now you've shut down, haha!
How'd it go?

[bryankloos]

Yeah, I tend to get ahead of myself.
With the float boxes it was very straightforward.
I just stopped feeding the fire and waited for things to cool down.
Once I was comfortable I added an extra inch to each pan and shut off the feeds.

I then drained out what was in the head tank back to the collection tank (outside and colder) and rinsed the head tanks with permeate and drained.

I only went through maybe 3-4 gallons of extra evaporation during the cooldown.

It was good.

[Andy VT]

Cool. What did you do about the first float box which I assume was luke-warm sap?

[SeanD]

I have a mark on my feed line for when I need to stop firing and flood. If it's been a longer boil and I know the box will stay super hot, I may be more conservative and stop a little earlier. I just have the one float box on a 2x6. The flooding goes to both pans. Once the front pan gets to the top of the cutout, I shut the valve between the pans. I don't do the thing where people pour off the nearup and set it aside. Nothing against that, I just haven't needed to .

Once I get all of the concentrate drained into the pan, I bring the back pan back up to a boil with a few small pieces or some soft wood. Once the back pan starts to boil, I use a sauce pot to scoop the boiling sweet from the front of the pan into the float box - which is at the back of my pan. I stick a thermometer in there and when it hits 200F, I stop.

I just have the one float box, but to your hunch, it's a good idea to get all of your sweet north of 180F (I go to 200F). I had a horrible situation with ropey sap years ago and the source was the float box. Since I've switched to bringing the float box up to 200F, I haven't had ropey sap (knock on stainless steel).

The next morning, the front pan level is at or just below my normal depth and the back pan is a little high. For me that's perfect for getting started and drawing off in 10-15 minutes.

There are a couple of other steps for me because I clean the front pan every boil and I have residual sweet from the filter press, but that's the gist of it. Once you do it a few times, you get a feel for what works on your rig and it becomes routine.