Safety Switch Off Low Water Pressure Boiler. Turn the valves back to their original position to stop the flow of water. Low water pressure in the boiler:
The boiler flow switch is a boiler safety feature or device that prevents the burner from firing in times when the flow of water is interrupted. There shall be a flow switch or low water pressure switch installed by the manufacturer within the heater casing to monitor flow through the coil. No or to low water pressure in the boiler, water pressure sensor defective, cable to pump or water pressure sensor loose/not connected/defective:
F.22 dry fire too little water in the appliance, water pressure sensor defective, cable to pump or water sensor defective, pump blocked or defective, pump output too low.
Temperature difference too great (ntc1/ntc2) f.24: Low water conditions will literally melt the steel pressure parts. The operating limit pressure control (steam boiler) or the operating limit temperature control (hot water boiler) and high limit pressure or temperature control are below their cutoff setting. You should now be able to hear water flowing.