Newby is back with boiling questions.

[wmick]

With an elevated sap tank your flow through the float box will be higher (deeper sap depth in the pan) when the tank is full vs when the tank is nearly empty. We always need to adjust the float box as the levels drop in the head tank.

Do you have a float between your flue pan and your syrup pan? If it is just a partially open submerged valve you can get mixing back and forth which will kill your gradient. Most commercial evaporators have a float between the pans to prevent backflow and allow you manage different levels in your pans. We run 1" above the flues but 2" deep in the front pan but the sap drops about 6" as it enters the front pan.

I don't have a float between the pans.. When I built the Arch, it was my intention that the syrup pan could sit about 1.5" lower than the flue pan, with a float in between... but someone talked me into just leveling up the 2 pans..., so I just added an extension ring under the syrup pan.
I am open to trying the float idea... It would be a bit of work, but not out of the question. After boiling on it, I'm fairly certain that I would need much more than 1.5 "drop" between pans to keep the float box fed and working properly... (closer to your 6" likely) Definitely something to think about.. I do like the idea of back-flow prevention, and separate pan depth control. But then again... Just a couple more things for me to mess around with. Will give this some serious thought.
Thanks

[ennismaple]

Once the float between the flue pan and the syrup pan is set you never touch it for the day. Yes - you keep an eye on it but given the fluid levels between pans stays relatively constant (vs the falling head in the sap tank that feeds the flue pan) you set it and forget it.

As long as the end of the pipe that joins the flue pan to your syrup pan is above the fluid level in the syrup pan you can control the flow using a simple valve. It prevents backflow but is more work to maintain constant levels.

[Sugarmaker]

wmick,
I believe most drop flue or flat pan systems are set at same level. Float box may work but not sure its necessary between pans? May need more info on that. But I am pretty sure that you wont be able to get a good gradient going in the syrup pan if it is leaking from one partition to the next. If leaking, its just like one big open pan and you can make syrup, but the batches will be much larger and take longer to get to syrup. Which kind of sounds like your last boils.
Regards,
Chris

[Big_Eddy]

wmick - I've read through the thread again and I can't find where you tell us what depth you are actually boiling at. It makes a big difference in the "flow" through the evaporator.

If you are running at 2", then your draws will be larger, and further apart than if you are running at 1" for instance. Much more than twice as large and twice as long between.
Running shallow drastically reduces the intermixing within your pans and therefore the gradient is "steeper" between sections of your pan.

However running shallow even more drastically increases the risk of running dry and burning pans, either due to a fast transition from almost syrup to smoke, or the inability to replenish sap fast enough. If your float pan or interconnecting pipes are not right at the bottom of the pans, or too small, this becomes even more of an issue. I have 1" pipes connecting my pans, and if I am trying to run at 1" and boil hard then the depth in the flue pan drops to about 1/2", and very little sap is able to flow forward to the syrup pan through that 1" pipe. Makes for some excitement when drawing off, if nothing is flowing forward to replace the drawn off liquid.

You're going to take a few goes before you get a real feel for your setup, but you seem to have a good setup and a good understanding - now you just need more sap to play with . (don't we all!!)

[wmick]

wmick - I've read through the thread again and I can't find where you tell us what depth you are actually boiling at. It makes a big difference in the "flow" through the evaporator.

If you are running at 2", then your draws will be larger, and further apart than if you are running at 1" for instance. Much more than twice as large and twice as long between.
Running shallow drastically reduces the intermixing within your pans and therefore the gradient is "steeper" between sections of your pan.

However running shallow even more drastically increases the risk of running dry and burning pans, either due to a fast transition from almost syrup to smoke, or the inability to replenish sap fast enough. If your float pan or interconnecting pipes are not right at the bottom of the pans, or too small, this becomes even more of an issue. I have 1" pipes connecting my pans, and if I am trying to run at 1" and boil hard then the depth in the flue pan drops to about 1/2", and very little sap is able to flow forward to the syrup pan through that 1" pipe. Makes for some excitement when drawing off, if nothing is flowing forward to replace the drawn off liquid.

You're going to take a few goes before you get a real feel for your setup, but you seem to have a good setup and a good understanding - now you just need more sap to play with . (don't we all!!)

I've tried different depths.... This last boil I had it at approximately 1.5" at the float box... which is deeper than I'd like for the flue pan.... but I've had some close calls up in the syrup pan when I try to run shallower... When things get hot, I'd say I'm at about 1" in the syrup pan. Even at this setting... when things get roaring to the drawing off stage, my level in the syrup pan goes down to the point my thermometer almost sees air (its about 1/4"" off the bottom) and the flow from my draw off valve almost stops... (its right at the bottom of the pan) ... Very Scary.
I up-sized to 1.5" pipe between the pans this year.... as it was way too small before (1/2" )... I am going to increase the size of all my fittings for next year... Draw-Off, tank to float and float to pan,... Try to take all the flow restrictions out of the mix...
Yep - Unfortunate to be out of sap.... but then again, just in the nick of time for my marriage to survive for while longer.... (till hunting season, anyway)
Thanks for the tips.

[PaulRenaud]

I have a 2x6 setup that I run with about an inch in the evaporator and 1/2 to 3/4 inch depth in finishing pan. Am able to start a trickle when I draw off and don't seem to have a problem pushing the syrup along between the pans. I use a hydrometer to check when to draw off.

But my question is how do I know when the syrup that I am drawing off drops below the target brix level so that I should stop the draw? Sure I can constantly take a sample and check with the hydrometer, but is there a way of telling visually? Thanks.

[mainebackswoodssyrup]

You’ll have to check it manually on when to close the valve.. The only other way is to purchase an auto drawoff. We have one for our 2x6 and love it.

[Russell Lampron]

But my question is how do I know when the syrup that I am drawing off drops below the target brix level so that I should stop the draw? Sure I can constantly take a sample and check with the hydrometer, but is there a way of telling visually? Thanks.

Do you have a thermometer near the draw off in your pan? Watch the temperature at the draw off and open and close the draw off valve as the temperature fluctuates.

[30AcreWoods]

If you don't have a horizontal probe near your draw off valve, you could clip a digital thermometer on the side of your pan at the valve location. Just use one of the apps online that will tell you the appropriate compensated temperature for syrup at your location on any given day (altitude, pressure, etc.). Once things get moving nicely, you should be able to crack the valve just a bit and maintain a relatively continuous flow. This will allow you to boil sap to syrup in the minimum possible time - which might change your grades.