Evaporator Freezing

[Toblerone]

Hello. I have just set up our new rig with a 2x6 flat (no flues) pan that is divided into 3 channels. Do I have to worry about sap/sweet freezing in the pans? I know if I had flues, the freezing could pop the seams but does that hold true for flat divided pans? It's going to get down to 15 degrees on Thursday, should I put a 100W shop light in the fire box or do I even need to worry?

Thanks in advance,
Dave

[brookledge]

You shouldn't have any problem once the pans have become sweetened. Look at it this way how many times does sap freeze in buckets hanging on trees and it doesn't blow them apart. With a flat pan there is vertually no restiction for the ice to expand
Keith

[gmcooper]

Once pans are sweetend the sugar content is up and the freezing point is lowered. For really cold below zero I have used a light. Might get some freezing but not solid ice.

[Swingpure]

So if you have boiled for several days in a divided pan, but then you get a week of below freezing temperatures, would that hurt the pan if you have left the sweet in the pan? (No flues)

22838

[DaveB]

So if you have boiled for several days in a divided pan, but then you get a week of below freezing temperatures, would that hurt the pan if you have left the sweet in the pan? (No flues)

It shouldn't. It becomes slushy but won't freeze hard if you've sweetened (or increased the sugar content) in the pans. Some producers put a 100 watt bulb in their fire box if you're worried about it.

[Vtmbz]

It can get very cold here even in season. To solve this problem I bought an automotive antifreeze tester. It tells me how sweet i am with a freeze chart attached. DO NOT put the tester in the pan or returnthe sample to the pan. Take a small drawoff into a paper cup. I use a new tester and for sap testing only. Surprising how sugar lowers the freeze point.

[BCPP]

Even with flued pans I've had no issues freezing. My biggest problem with freezing is the supply and incoming float pans. Takes a while for heat to transfer back from evaporator to thaw the float feed and lines - some exciting times if I'm not awake yet and start the evaporator prior to ensuring sap can get to it!

[DaveB]

Even with flued pans I've had no issues freezing. My biggest problem with freezing is the supply and incoming float pans. Takes a while for heat to transfer back from evaporator to thaw the float feed and lines - some exciting times if I'm not awake yet and start the evaporator prior to ensuring sap can get to it!

I forget about that too and I've been doing this for 33 years now lol. The main problem I have is the incoming line freezing. I have a 1" pipe from my feed tank and if it gets really cold it will freeze. I've had to take it apart and put the pipe pieces around the evaporator until they thaw so yeah, that can be the hardest part. Best to not get a roaring fire going until everything is flowing and having a 5 gallon bucket of "oh crap! sap" (as we call it) available.

[maple flats]

4 or more hours of good hard boiling will get the density high enough that you will be good down to at least 10F, 6 or more hours will get it to 0F without freezing solid. Some slush may form but it will not freeze.

[Swingpure]

So we will be having a number of days coming up where the sap is flowing (we will see how much) and I should get started boiling hopefully early this week. However as I could see happening in the forecast, the end of the month is turning cold and as each new day pops up on the forecast, the cold gets extended. It drops down to -14° C / +7° F on some of those days.

I can put an automotive trouble light in the firebox with as high as wattage incandescent bulb I can find up to 100 w, or another thought is when the concentrated sap cools down on my last boil before the extended freeze, is that I draw off all of the concentrated sap into five gallon pails, keeping in mind the order I filled them, and then store them outside or inside my heated garage that I can keep just above freezing, and then pour them back into the pan in reverse order, somewhat keeping the gradient.

Is this also a viable alternative?

22862

22863

[nhdog]

maple flats
different evaps would require different lengths of time to get to specific Brix readings. Can you correlate your boil times to Brix levels?

[maple flats]

Actually when I was first learning I was told by my mentor (a dealer) that 3 hrs good hard boil time will ge it to density enough to protect the pans. Boiling hard for 3 hrs removes enough water to raise the density to protect the pans, to be safe I just add an hor.
Yes, different rigs boil at different rates, but if boiling hard for those times the density is up enough to consider the pans sweetened!

[bigschuss]

So we will be having a number of days coming up where the sap is flowing (we will see how much) and I should get started boiling hopefully early this week. However as I could see happening in the forecast, the end of the month is turning cold and as each new day pops up on the forecast, the cold gets extended. It drops down to -14° C / +7° F on some of those days.

I can put an automotive trouble light in the firebox with as high as wattage incandescent bulb I can find up to 100 w, or another thought is when the concentrated sap cools down on my last boil before the extended freeze, is that I draw off all of the concentrated sap into five gallon pails, keeping in mind the order I filled them, and then store them outside or inside my heated garage that I can keep just above freezing, and then pour them back into the pan in reverse order, somewhat keeping the gradient.

]

I've never had a problem in 20 years of sweet freezing in my 2x4 pan. If you remove it and keep it in your heated garage for any length of time you risk it going bad. By keeping it in the pan you can at least fire up the evaporator every few days to kill bacteria. I'd personally just leave it in your pan. Keeping it warm with lights? Can't hurt. I've never done it, and I've never had a problem.

[SeanD]

Same issues here with the sweet never freezing solid, just a slush at most. Probably less of an issue boiling concentrate now (and the rarity of deep freezes now). There are simple highly accurate tables for temp/density correction, and obviously for density/boiling point. I wonder if there is anything simple out there for density/freezing point. My searches turn up tables and calculators that are too difficult for me to understand. Molal? I should have paid more attention in chemistry class!