the pressure relief valve on the top of the tank needs replaced
Turn red dial to pilot.Shut the cold water feed off. There is a drain located at the very bottom of the tank youll need to hook a hose or hold a bucket and drain some water out of that. It doesnt need to be much a few buckets or a couple mins of hose will be fine. Then simply un-screw the old one. Put teflon tape and pipe dope if you have it around the new one and tighten in securely. open hot water at your sinks and turn cold water to tank back on slowly and let the sinks run until all air bleeds out and then shut them off. Re- light pilot. Done.
strictly speaking there are qualifications for this kind of repair hot pressurised water can be very dangerous
Turn the inlet off , turn the gas off or electric, drain the tank by connecting a garden hose to the drain valve remove the pressure valve and install a new one.. Remove the hose close the drain open the pressure valve turn on the water open all of the faucets in the house to allow all of the air out of your system have some one watching the sinks it could make a mess, relight the pilot light or turn the electric back on. Remember to use a little teflon tape on the threads of the pressure valve.
Gas fired? Place thermostat to pilot to keep burner from coming on while you work. Turn off cold water supply to Hot Water heater. Open all the Hot water faucets in the house. Get a Pipe wrench and some pipe dope. and of course the new relief valve, place some towels under the relief valve as some water will leak out. Put pipe dope on the new relief valve threads, remove old relief valve using steady pressure, immediately put in new properly pipe doped relief valve, screw in hand tight, then use pipe wrench until it is set. Don't over tighten. Dry off area around new valve so you can more easily detect leaks. Reopen supply water to HW heater, let faucets run until no more air comes out, then shut faucets. Put regulator back on. Done.
