we have gotten all the leaks fixed and the led light comes on for the heater and i can hear the contactors click when the heat is turned up or down but it will not heat the water. the heater is a 2001 Ramco, 220 v, when checking for voltage across the heater terminals, there is nothing, with the pumps on. Is the heater bad or am I missing something.

how do you test a flo switch to see if it is good? I don't want to keep replacing parts if they are not bad

I would assume it is just like a pressure switch in that you check for continuity. One way should be zero (closed)and the other infinite(open). You could also jumper between the wires going from the switch to the board to determine if it is the switch or something else.