Grade Change due to heat

[johnallin]

So, I've been playing around with a water jacketed draw off tank made from my old w/j bottler. Smoky Lake has introduced the idea and it's an amazing use of condensate. The idea is to keep the syrup hot enough to filter without having to re-heat. It's a great idea, the syrup will maintain 150° +/- for the duration of the boil.

But...Since we don't make much more than 3 gallons in one boil, and that takes about 4 hours, the first few draws of syrup sit in the heated tank for a full 4 hours. I'm starting to think that's not a good thing and may be a partial cause for the darker than normal syrup we've made this year, or adding to what already is a year for dark syrup.
I further think that if we were larger and emptied the heated tank on an hourly basis, it would make little difference and may be better than re-heating in a finisher. I came across a chart somewhere last year that plotted grade change based on temp and time. I believe if we were making 10 gal/hr like some of you, it would be a no brainer, but for the small producer like us, it may be detrimental. Any thoughts? Thanks-John