I did manage to get some plumbing on the boiler done yesterday when it was down pouring rain. It is, after all, a very long term project.
I am on the plumbing-it-up aspect of things which is not something I like. I live a ways from the hardware store so when I don't have the right fitting, a plumbing job might mean several trips to the store 30 miles away. Yesterday meant two such trips, but the depressing part was spending $250 dollars and seeing only a few pieces of pipe cobbled together...with far more to go.
I worked on the modine part of the build, completing that loop and now need to start the piping from the boiler to my propane boiler.
The only real question I have right now is if I need a check valve on my modine return line. I can either plumb it back to the bottom of the New Yorker Boiler, or Tee it in with my return from the Propane Boiler, but was thinking I might need a check valve to keep the water from going back through the modine when that emergency dump zone is not activated. It would not go past the closed zone valve, but a check valve would ensure the return water was diverted properly for sure.
So, do I need a check valve?