Cleaning flu pan during season

[Super Sapper]

How often do you clean your flu pan during the season? I pulled my hood and preheater off and found that my drop flu pan was full of niter. I have a 2 x 6 with a 4 foot drop flu. I boil raw sap and did not think that it would niter up like this (first year with it). I need to clean the syrup pan every 300 to 400 gallons of raw sap or it starts to burn the niter on the bottom. I tried reversing the syrup pan and it seemed to work pretty good. If it works to reverse the syrup pan why does the flu pan niter up all the way to the influent float box?

[maple flats]

I clean my flue pan every 2-4 boils depending on how it looks. But then I have a Lapierre flue pan washer. I drain the pan into a barrel, then connect a pump to the washer. I pump permeate thru the washer for 60-75 minutes, it goes to drain, then I pump the drainings back into the flue pan and I'm ready to boil.
Before I had the washer, I only cleaned the back pan 1 or 2 times a season.

[Sugarmaker]

Humm,
You sure that's niter? Or just residue from boiling? Does it have thickness to it and flake off? What is the grade of your finished syrup? Did you make a lot of Golden delicate?
I did not clean my flue pan this season until done. We are small but a little bigger than you. 3 x 10 rig, 5 ft flue pan, steam away, boiling raw sap with wood. Boiled 6500 gallons of sap.
Now as far as cleaning, You can clean it ever time you boil if you want. Just a little time and labor to drain and at least rinse with hot water.
Hummm. The experts will be along shortly. I just come here to learn things!
Regards,
Chris

[FDA]

You're making syrup in the flue pan. Your fire isn't hot enough or your not drawing off enough syrup and you're making syrup in the center part of the pan causing syrup to back up. Try adding a blower to get things hotter to help establish gradient and or learn to watch your boil. On a small rig like a 2x6 boiling raw sap you need to draw off sometimes early to keep gradient established. Lately I have seen a lot of guys who try auto draws on little rigs and have fits with flue pan niter as well as producing darker syrup.

[Super Sapper]

It is niter and is thicker than it looks on the picture. It did flake off in a couple spots. I have checked the sugar concentration coming into the syrup pan and it ranges from 22 to 26% so I am not making syrup in the flu pan. I have a blower for auf and a good gradient established. I do have a lot of niter, syrup pan needs to be cleaned or reversed every 300 gallons or I will start burning the niter on the bottom. I can only get about 6 to 8 gallons of syrup through a short bank 7 inch press. The weird part is that I started reversing my syrup pan instead of cleaning every 300 to 400 gallons and it worked pretty good at lifting the niter off the pan. If that works why do I get niter in the flu pan all the way back to the float box. I even had light deposits in the bottom of the float box.

[wnybassman]

I rinsed my raised flue out about halfway through the season for the first time ever this year. I was surprised at the gunk that came out. I may make a habit of it.

[SeanD]

Up until this year, I only cleaned the back pan once or twice. This year between the warm spells, hard freezes, and the extra time, the RO has given me, I've cleaned it a lot more - maybe 4 times. It does give me peace of mind because I worry about ropey sap which hit me a few years ago. I just gave it a light brushing and a rinse with the hose. One time I boiled water in it. I have noticed I have a lot less scum back there during boils and my front pan has had a lot less niter.

[johnallin]

You're making syrup in the flue pan. Your fire isn't hot enough or your not drawing off enough syrup and you're making syrup in the center part of the pan causing syrup to back up. Try adding a blower to get things hotter to help establish gradient and or learn to watch your boil. On a small rig like a 2x6 boiling raw sap you need to draw off sometimes early to keep gradient established. Lately I have seen a lot of guys who try auto draws on little rigs and have fits with flue pan niter as well as producing darker syrup.

Sapper - you've got lots of nitre, but you're not making syrup in your flue pan.

[abbott]

Are you running the sap level in your flue pan really low? That might contribute to niter cooking on. Just a thought.

I have a 40"x10' rig with 7' flue pan and will process 15000-20000 gallons of raw sap a year. In the past I have typically cleaned the flue pan with pan cleaner 1-2 times during the season and at the end. This year I'm planning on just leaving it alone until the end. The tops of my flues are discolored, but no real depth the the scale so I'm not going to worry about it.

I think it comes down to this: everyone's operation works a little differently. The way niter forms and where and when it builds up varies from person to person, year to year, and within the year. If your scale is building up, you'd be wise to clean it. If it's just a thin layer, then it's more of a personal preference of how often you clean it.