Pressure relief valves, also as known as a blow-off valves, are a vital component of a boiler. Without a properly working valve, dangerous levels of temperature and/or pressure may build up in a home’s heating system. Extreme pressure within the system could cause the boiler or water lines to rupture. If the temperature and pressure within the boiler are in the normal range and the pressure relief valve is leaking, it is a sign the valve is defective. Replace a defective, leaking valve right away.
Shut down the power to the boiler. In most cases, this will involve switching off the breaker specifically designated for the boiler. Also shut off the fill valve that supplies water to the boiler system. Wait a few hours to allow the boiler and water to cool.
Wrap plumber's tape around all but the bottom two threads of the new pressure relief valve. Turn the new valve into the boiler and tighten it with the pipe wrench. When turning the new valve into the boiler, ensure it is straight and pointed in the same direction as the old valve. Reconnect the drain pipe if necessary.