I retried with my last boil (I'm a small backyard guy with 20 taps on a barrel evaporator).

I was mainly worried about the sap flash scorching in the tube. I used 10' of 3/8" copper tubing wrapped about 6 times around the stove pipe. It was wrapped as tightly as I could but it was not 100% in contact since the stove pipe isn't completely round. I also made sure to have a constant downward wrap as I was worried about having a place where something could just sit in the tube and boil. This would make sure the tube would drain by itself.

I used the aquatec 8800 from my RO system to provide the flow. I used 1/4" line to connect the pump to the copper with about 18" of wrapping coming off the stove pipe to try to prevent the heat from the stove pipe from melting the plastic 1/4" tubing.

Initially I had the wrapping high on the stove pipe as that's less hot, but I pulled it lower as I got more comfortable using it.

I had the sap recirculating to my 32G sap storage, but it was obvious that that would not raise the temperature very much or quickly.
I switched to recirculating in a 5G bucket with about 1G of sap in the bucket. This allowed be to increase the sap temp.
The sap was about 50F in the storage, and it would raise to about 85F by the time I needed to add more to the evaporator (about 5-10 minutes).

I don't have a way to trickle into the evaporator yet, so I would add 1G sap to the 5G bucket, wait for it to come up to 85F, then add that to the evaporator, and repeat. I made sure to never have the pump draw air so the flow would stall and potentially flash the sap in the heater tubing.

I could probably double the tubing wrapped or insulate it better to the stove pipe to increase the performance. I could try to add a couple taps from the line to feed both my evaporator trays, but that would be a lot more tubing and connections.

Once I was out of sap, I just filed the 5G bucket with permeate and let it circulate until the stove pipe was cool enough.

image-20190329_120026.jpg