I am using a 12v Parmax 3 ( 40 psi) pump to pump my water system at a cabin. The pump connects to a small Bosch W125k propane water heater.. All worked well until I had a freeze up... So after replaving the pressure switch on the pump and diaphram on the heater, it does not work like before. Pump and heater work however I cannot keep a steady stream of water from my shower unless I also turn on another tap ??? It seems like if there is not enough demand, the pump does not generate enough pressure to keep the propane demand heater lit so propane flares up and down and the water does as well...UNLESS I turn kitchen tap full on .. Any ideas on what I can adjust to correct this as same system worked fine before I screwed it up by forgetting to drain it ..