I've built a couple of these and if I had to do it all over again, I'd probably simplify things even more and use more plug and play components vs custom building everything. On one unit I put in a parallel pump bypass line with an ultra low crack pressure
check valve (0.3psi = 8 inch of water). If pump fails or shuts off while sap is still flowing it can naturally bypass the failed pump.
Temp controller that is pre-built on Amazon that has 2 independent sensors and outlets. This wasn't available when I built my units, but if it was, I would've tried it.
https://a.co/d/1fGQ4rm
This will let you plug the 12v transformer right into one outlet and control the pump. Then you can plug a 120v heater / seed germination mat in the other and set your temps for both.
Here is a good power supply for this setup
https://a.co/d/82m0HTp
Easy 120v heater that's 20W (search for one that's best size for your pump box
https://a.co/d/asaajfZ
If you have to transfer sap, use a level controller and a seperate pump / power supply
https://a.co/d/5zrJOWd
I use all push fit (john guest style) connectors so it's super compact and simple to assemble, disassemble, clean etc.
They make low pressure (0.3 psi) check valves in 1/4" that you could put on each line at the pump manifold to prevent backflow. They are kind of pricey if you have a lot of lines. I use CV spouts and haven't felt compelled to add these.
https://www.freshwatersystems.com/pr...k-pressure-red