Undesirable boil

[Arctic Fox]

I seem to experience a different boil when sap flows from the back pan into the front pan during a draw off. Rather than a normal boil the bubbles seem to explode and splash hot sap out of the pan. It almost sounds like popcorn. I'm wondering if anyone else has experienced this and if so, do you know what causes it?

[Arctic Fox]

Apparently no one else has experienced this. . .

[mol1jb]

How much do you draw off at a time? Do you open the valve wide open or just a trickle?

[Sugarmaker]

How deep is the sap in this area? Sounds like it may be too shallow??? With out being there its tough to help. May some pictures? I dont think I have had this happen but if you search on here you may find something??
Regards,
Chris

[Arctic Fox]

You can see the weird boil in this video. https://youtu.be/hi4EMPRX3IE

Usually I draw off with the valve about 1/2 open. The sap is relatively shallow, but it seems to only exhibits this behavior when it first comes in to the front pan during a draw off. I can keep the level low while I'm getting closer to syrup in the front pan and the boil is normal.

[maple flats]

I'm not sure, but maybe if you open the valve less and have a longer draw.
I never had that popping, but before I got my auto draw I used to try to have the longest draws I could get. Unless the temperature got well above ideal I would get to about 7 over the boiling point of water for that day, and the valve would only get opened a crack, I often had a flow at draw off the size of a pencil lead or slightly more even when I had a 2x3 flat pan. I'd watch the temperature and tweak the valve as needed. I think about 10-12 minute draws may have been my longest on that 2x3. Then I got a 2x6 with a 2x3 drop flue pan. I continued to strive for long draws, but the flows were usually a little faster,. With that I sometimes got draws of 25-30 minutes but the typical was more like 15 minutes long. Then I got my first 3x8 and that practice continued. With that and no RO I often got draws of 20-30 minutes and I think my longest was over an hour. The longer draws always had several adjustments to the flow.
Now with an RO going to 8-12% concentration, high pressure AOF and AUF, a preheater in the hood and an auto draw I no longer get those real long draws, but I do regulate the flow so I don't get surging as the auto draw opens or closes. That is done using a ball valve between the pan and the auto draw. I adjust that valve by watching the temperature changes as the auto draw opens. If it rises too much I open that valve more, if it is too short of a draw I close the valve a little.
I wonder if that might help?

[PaulRenaud]

I'm not sure, but maybe if you open the valve less and have a longer draw.
I never had that popping, but before I got my auto draw I used to try to have the longest draws I could get. Unless the temperature got well above ideal I would get to about 7 over the boiling point of water for that day, and the valve would only get opened a crack, I often had a flow at draw off the size of a pencil lead or slightly more even when I had a 2x3 flat pan. I'd watch the temperature and tweak the valve as needed. I think about 10-12 minute draws may have been my longest on that 2x3. Then I got a 2x6 with a 2x3 drop flue pan. I continued to strive for long draws, but the flows were usually a little faster,. With that I sometimes got draws of 25-30 minutes but the typical was more like 15 minutes long. Then I got my first 3x8 and that practice continued. With that and no RO I often got draws of 20-30 minutes and I think my longest was over an hour. The longer draws always had several adjustments to the flow.
Now with an RO going to 8-12% concentration, high pressure AOF and AUF, a preheater in the hood and an auto draw I no longer get those real long draws, but I do regulate the flow so I don't get surging as the auto draw opens or closes. That is done using a ball valve between the pan and the auto draw. I adjust that valve by watching the temperature changes as the auto draw opens. If it rises too much I open that valve more, if it is too short of a draw I close the valve a little.
I wonder if that might help?

How did you determine when to end each of those long draws?

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[regor0]

When the temperature drops below syrup temp.


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