Finish pan flow issues

[LMP Maple]

Sorry this will be a long one. Have a 19 x 48 mini pro oil fired rig. This is my second year boiling on it. The first year I noticed that the thermometer would jump all over the place would go from 216 to 222 and fall and jump. I tried a new one and adjusting the height of the probe and cleaning to no avail. I became really good with my hydrometer as that was the only way I could trust what I was drawing off. In talking with many people I came to the conclusion that I was making syrup in most of the front pan with no continuous flow. This did not bother me all that much as the syrup was good and no problems with scorching or burning the pans etc. Then this past week, during one boil I noticed that the flow was actually working and I was chewing through sap having to increase my float to the front pan to keep up. The thermometer was actually working correctly climbing slowly and I was drawing at 219 -220 and was dead on. That night when I turned off the rig I noticed a pretty good accumulation of sugar sand on the final finish pan channel. I was glad I saw this and cleaned it and switched sides. Today when I boiled it went back to the way it was all last season, erratic temps, still making good stuff just more work for me. So this is my theory, with the accumulation of sugar sand the pan temp was higher and caused a more rapid boil which gave me the continuous flow and got things moving the way they should be. Does that make sense? Remove the sand, decrease the pan temp and not enough boiling to get things flowing. I would assume if I can increase my boil in the front pan it will get the flow going again. My thoughts are to add some more brick to the arch to try to get more heat on that front pan. On that note should I be trying to make a wall for the flame to hit and be forced up. Any advice with this would be appreciated.

[wnybassman]

I had to increase the depth in mine last week because we were getting wide temperature swings. Not sure how it got knocked out of adjustment, but I had to increase the depth by nearly a 1/2" to make sure the temp probe was submerged enough.

[ecolbeck]

This sounds like a frustrating issue.

Due to the inconsistent performance of the evaporator, I wonder if the issue is related to the heat output of the burner. Are you confident that it is operating correctly?

The presence of sugar sand doesn't cause the pan to get hotter or for the boil to increase. If that were the case, then sugarmakers would pray for sugar sand or add it to their pans to make syrup faster. Why its presence seemed to improve the performance of your rig is mysterious. I suspect it was another factor.

A float is designed to keep up with any rate of evaporation you would experience and shouldn't need adjustment based on increased evaporation.

[Russell Lampron]

I'm thinking that the real problem is that you weren't running your sap level deep enough. Also on my rig the first couple of draws will do the same thing. Once everything is up to temp it smooths out and the sap in the head tank disappears.

I increased the depth of my syrup pan from 1" to 1 3/4" in 1/4" increments until I found the "sweet" spot.

As far as when to switch sides, I do it every time that I boil again. I generally have to actually clean the pan when I've made 100 gallons.

[LMP Maple]

Thank you all for the feedback. I think the evaporator is running well overall. I had it set up by a tech at the start of last season we went with a 1 gpo nozel. It seems to boil well. I generally run at about 1" in the syrup pan I will try bringing that level up to see if I get a better flow today. I break down all the floats after every boil and bring them in and clean them so getting the float adjusted in the finish pan takes a bit after I fire, a little tweaking here and there. The float box pan has a set screw on the float so that is always consistent. The reason I thought the boil was better is I had to adjust the float to let in more sap to keep it at that one inch level as the boil really picked up that was the day that it was flowing correctly at that point I was at 3/4 inch. The sugar sand was really stuck to the bottom of the pan that is why I thought the boil would have been better in these spots. I will see how it goes today. Again, thank you all great to have all this knowledge, just want to run like the big guys in my tiny house evap:)