That's a real two stage. The external line wrapping around the back of the pump is the interstage line. On mine it was finned. Then the discharge line wraps around the front from the cast iron cooler to the top of the tank. I've had limited success with the automatic blowdown valves. After several months they seem to get stuck and the solenoid can't open them, just buzzes and it is hard to tell they aren't working.