Boiler top mounting arrangement for pressure relief valves

Claim 1

IN A CLOSED HOT WATER HEATING SYSTEM, IN COMBINATION, A BOILER, SAID BOILER BEING ABLE TO COLLECT BUBBLE LADEN WATER TO DEFINE A WATER LEVEL ADJACENT BUT SPACED BENEATH THE TOP OF THE BOILER, PIPE MEANS EXITING FROM THE TOP OF SAID BOILER AND ADAPTED TO SUPPLY HOT WATER TO CIRCULATE THROUGH SAID SYSTEM, SAID PIPE MEANS HAVING AN INLET IN THE BOILER AND EXTENDING BELOW THE WATER LEVEL THEREIN, A COMPRESSION TANK PROVIDING AN AIR CUSHION FOR THERMAL EXPANSION OF SYSTEM WATER, PIPE MEANS EXITING FROM THE BOILER AT A LOCATION ABOVE SAID REFERENCE LEVEL FOR TRANSFERRING AIR BUBBLES COLLECTING IN THE TOP OF THE BOILER TO THE AIR CUSHION IN SAID COMPRESSION TANK, A PRESSURE RELIEF VALVE HAVING A BOTTOM INLET OPENING COMMUNICATING WITH AN INTERNAL SEAL FACE THEREOF, SAID SEAL FACE BEING ARRANGED TO CONTROL FLUID DISCHARGE FROM SAID SYSTEM THROUGH SAID VALVE, AND DIP TUBE MOUNTING STRUCTURE DISPOSED IN SEALED RELATION IN A SEPARATE OPENING IN THE TOP OF SAID BOILER AND HAVING ITS UPPER END CONNECTED DIRECTLY INTO THE OPENING IN SAID VALVE AND HAVING ITS LOWER END PROJECTING INTO SAID BOILER TO A POINT BENEATH THE SAID WATER LEVEL THEREIN TO SUBJECT THE SAID SEAL FACE TO EXISTING SYSTEM PRESSURE WHILE EXCLUDING AIR OF SAID SYSTEM FROM CONTACT AND HENCE POSSIBLE LEAKAGE THROUGH SAID SEAL FACE.