Glad you got it working. Sorry the plumber wouldn't remove the check valve. If the check valve down the well on the pump is not working it must be replaced. The extra check valve up top takes some pressure off the lower check, which keeps it from closing as well. The extra check valve up top also mask many problems, and can cause a water hammer on pump start that also causes a pressure surge. The surge from the check valve water hammer was probably was was causing the union to break. It would have been better to remove the check valve but just getting rid of the union will probably solve your problem, as everything else is rated for much higher pressure.
It is good that you are educating yourself on how pump systems work. As you can see just taking the contractors word for it can sometimes be the worst thing you can do. Hope you can find a trustworthy contractor to help, but they are hard to find these days, which is why so many people are learning to DIY.
It is good that you are educating yourself on how pump systems work. As you can see just taking the contractors word for it can sometimes be the worst thing you can do. Hope you can find a trustworthy contractor to help, but they are hard to find these days, which is why so many people are learning to DIY.