Going way over draw temp

[Windy Acres]

So we started boiling concentrate this year on or 2x8, and no matter what I did for adjustments, I just couldn't find a sweet spot where the temp wouldn't rise 3 or 4 degrees in the middle of the draw, we have AOF/AUF and burn all kiln dried hardwood, split to the proper size, we average around 85 gph, full hoods and preheated, and a bubbler, stack temp holds 900-1000. I'm wondering if I need to cut down the auf and not run it so hard with concentrate?

[maple flats]

Does it do that only on the first draw after you reverse flow or all of the time?

[DrTimPerkins]

Where are you placing the temperature probe? Have you tried moving it further back in the pan? Is the last partition noticeably cooler (less rapid boil)? When you switch sides, does the problem change from side-to-side?

With our former evaporator (Leader 3' x 10') boiling 15-17% concentrate, on the first draw of a boil or after switching sides we would have to start drawing off about 2.5 deg F cold, and it would rise about 2.5 deg F over the set temp, and make about 10 gal of syrup in that first draw.

On the new Lapierre Volcano 2000 4' x 12' boiling high concentrate, we start drawing off 3.5-4 deg F early, and it can rise to over 10 deg F above syrup on the first draw. The front (syrup) pan on this rig is 4' x 8', and we're running 2" deep, so there a lot of syrup in there. We end up with about 25 gal in the first drawoff. Can get a little exciting, but with the Riello burner you can adjust the heat anywhere from 20-100%, so we'll dial it back a little until after the first draw is done. Once that is over, as long as you don't change anything else, with the modulating drawoff it just runs almost perfectly smoothly for hours. Switching sides can be equally exciting, but we find we haven't had to switch sides very often these past few years.

[Haynes Forest Products]

I can sympathize with the out of control fright train coming into Union station. On my rig it was to much heat with a too little draw off valve and not knowing that I was drawing off at the coolest part of the finish pans. You mentioned concentrate but what percent because going from 2 to 4% was crazy for me the first time then 4-8% made me do some changing of the rig BUT 22% took some real changes. The problem people get into is they try and do to many changes without really knowing what is the main cause. You want to really feel like burning the shack down is have a bad temperature probe that fluctuates back and forth never settling down to a constant temp. I made my best syrup once I took the time to calibrate ALL my probes and then trusted them. That includes calibrating the PID to the probe.

Once I realized I was making over density syrup in my first channel of the first finish pan nearest the flue pan and then it ran thru the other 3 to the undersized draw off then I made the big change. OH YEA all the time I was running my oil gun on high fire............What a dumb a$$ I was. Just dont make 5 changes all at once because you will never know what was the biggest contributor.

[Bucket Head]

Chuck,

What did you "change" when you had over density in the channel next to the flue pan? Was it just a draw off change or did you change the plumbing so that channel became the last (finish) channel. I have considered doing that with mine since that channel is over/closer to the hottest part of the firebox. The front channel is cooler being on the "outside" so to speak and the repeated door openings to load wood doesn't help either.

[Potters3]

Have had the same issues with spiking temp on draw. Few small changes seemed to have help. We boil 16 - 18%
2 1/2" to 3" deep in the front pan
start drawing a little early, a trickle to get it going, never open draw valve past half way. scoop over sap if needed.
clean the front pan when it starts to act funny

[Haynes Forest Products]

Steve I have become a SS milk house pipeline whore I buy up all the fittings I can find. I have a assortment of all kinds of specialty fittings. I have a Lapiere waterloo small pan set that you can reverse but you have to switch out all the equipment from side to side. What I ended up doing with an assortment of 2" sanitary fittings and elbows is come out of the flue float box and skip past the 2 finish pan plumbing and into what used to be my draw off port. I then put the draw off plumbing on the channel next to the flue pan. That made it run like it should very predictable and steady. I also did away with the bypass plumbing and got my drawoff plumbing short and sweet. Once things settle down I can run it on high fire

[Maple Man 85]

This is a common issue with our rig as well, when we are done for the day we drain the syrup pan (4x6) into our draw tank and clean the pan. From there we pump it back into the pan (this jacks up the gradient) so our 1st draw is like 30 gallons! The first time this occurred I about s#@! cause we were not prepared. But it was really cool to see that much syrup came off at once (we prefer to have the 1st draw come off a bit heavy). I'll put the hydrometer right in the draw tank and pull hot sap from the reverse flow valve to achieve the proper density and then send it through the filter press. That how we get around it (then play with the auto draw temp setting). The thing to remember is that syrup comes off the same way sap enters. Here is what our 1st draw tends to look like...

https://www.facebook.com/northwoodsmaplefarm/videos/607994252868512/

[Windy Acres]

Yes this happens all the time, we are boiling 13-15%

[mellondome]

I boil 18%. When I shut down, i keep one partition of near syrup from the front pan. When I start up i will add this to the draw off box just before the front pan starts to boil. As the next to last section nears syrup ( using a hydrometer) i will start a draw. From there, i will have a constant draw the entire boil from the bypass of my autodraw. The autodraw is set to 2 deg over syrup to keep things from getting out of control. When it is all blended in the drawoff tank, the highs and lows balance out.