Quote Originally Posted by berg2666 View Post
There is more then four stages here, each condensor has two stages.
Anyway, you can use an aditional 4 stage simple thermostat. Don't worry about the head pressure control
of the comps. it's probably in the condense units.
I forgot to mention that you must install a seperate water pump with a check valve on the discharge side
for each heat exchanger and please don't forget the safety devices such as water flow switch and freeze protector
for each heat exchanger. Cheers