Preventing Backflow/Pan Mixing

[ecolbeck]

I fired my new/used CDL 18x48 drop flue hobby pan for the first time yesterday. As things progressed and a gradient started to form I noticed a couple of things. When I add wood (every 6 min or so) the boil in the pan drops and sap rushes down into the spaces in the flues that had been occupied by steam. This causes a major backflow from the syrup section and I almost had a heart attack as the level in the front dropped from 3/4" to what seemed like a few millimeters.
Is there some way to prevent or minimize this backflowing? It seems like the mixing it causes will make it difficult maintain a gradient and make syrup. Does anybody have ideas for a simple check valve or something? Thanks!

[DrTimPerkins]

A check valve between flue lanes would stick, leading to a melt-down. What you're describing is pretty typical....you really needn't worry about it. The gradient will redevelop just fine. Just keep putting wood too it on a regular schedule and do it quickly. If the pan level seems to drop too low during these times, then run it just a bit deeper.

[SmellsLikeSyrupNH]

Thanks Dr Tim, I also ran my 2x6 for the 1st time this past weekend and I also had the gradient mixing issue. It started off great, see the picture, but as my day wore on it seemed as though all 3 of the channels in my syrup pan had darkened up and the gradient was lost. My draw off channel still seemed to be the one where the syrup was concentrating, I just was curious if I will ever get the gradient back at this point?

15567

[Big_Eddy]

I fired my new/used CDL 18x48 drop flue hobby pan for the first time yesterday. As things progressed and a gradient started to form I noticed a couple of things. When I add wood (every 6 min or so) the boil in the pan drops and sap rushes down into the spaces in the flues that had been occupied by steam. This causes a major backflow from the syrup section and I almost had a heart attack as the level in the front dropped from 3/4" to what seemed like a few millimeters.
Is there some way to prevent or minimize this backflowing? It seems like the mixing it causes will make it difficult maintain a gradient and make syrup. Does anybody have ideas for a simple check valve or something? Thanks!


A check valve between flue lanes would stick, leading to a melt-down. What you're describing is pretty typical....you really needn't worry about it. The gradient will redevelop just fine. Just keep putting wood too it on a regular schedule and do it quickly. If the pan level seems to drop too low during these times, then run it just a bit deeper.

One more thing - if your "almost syrup" is flowing back into the sap pan, then your float valve is not opening up fast enough. Really what you'd like to see when the boil drops is for the float to open and new sap to rush in pushing the concentrated solution forward. Take a look at your float and inlets to see if there is anything you can do there to allow a faster response.

But truly though - while a visible gradient looks neat, it really does nothing to increase your boil rate or improve the syrup. If sap is going in and steam is coming off, then you're going to make syrup. Mixing may affect the size of your draws and the length of time between them, but those are much more affected by the depth in the pans and the consistency of firing. Focus on keeping your evaporation rate up and consistent, and the rest will follow.

[DrTimPerkins]

But truly though - while a visible gradient looks neat, it really does nothing to increase your boil rate or improve the syrup. If sap is going in and steam is coming off, then you're going to make syrup. Mixing may affect the size of your draws and the length of time between them, but those are much more affected by the depth in the pans and the consistency of firing. Focus on keeping your evaporation rate up and consistent, and the rest will follow.

Excellent advice. No need to spend much time fretting about it.....gradient happens.

[ecolbeck]

Thanks for the help guys. I'll stop worrying about it right away!:)

[Biz]

I am also unable to draw finished syrup off my 18x48" CDL. Too much mixing and not a good way to prevent it. I draw off 3-4 qts of unfinished syrup off every couple of hours and finish off in my kitchen.

Dave