I'm using THIS pump from amazon. You can run the pump of a 12v battery or you can get a power supply which is what I did.
You don't want to heat up your storage container that's just begging for any unused sap to spoil and make a mess of your tank.
Instead of pumping warm sap back to the storage tank its better to send cold sap back to the storage tank. In the picture you can see how I put a tee fitting in and a valve to control the flow that goes back into the tank. There is another valve right before the sap goes in the pan. To set it up and adjust flow it goes like this:
Both valves wide open
Start pump and get flow
Close the valve on the tee just enough that you get a solid stream of water into the pan. This should be a very small adjustment.
Adjust flow into the pan with the valve near the pan. This valve can be anywhere from wide open to almost closed depending on how much flow you need to meet your evaporation rate. You want to make sure you have at least a steady drip going into the pan or you will overheat the sap in the coil.
With 2 valves setup like this you have infinite control of flow of sap into your pan. From super slow trickle to max flow from the pump.
To flush the coil with this setup I get a 5 gallon bucket of clean water ready to go. I shut off pump, then put the pump suction into the bucket of clean water. Shut the valve on the tee and open the valve going to the pan wide open. Direct the outlet of the tube away from your pans (I have a flexible piece of tubing the last 18" or so going to the pans so I can just point it onto the ground). Turn the pump on and pump the water thru the coil. After flushing open up the tee valve and let the coil drain onto the ground. You now have a clean coil that will dry out.
I'm using push to connect fittings that I can remove from the copper when I'm done. I remove them so there is no chance of them melting.
My copper tubing is 3/8" OD tubing 25 feet long. It could be longer but 25 feet fit the budget.