My hot water system, is leaking from the pressure valve, how do I change it?

You have a simple fix, start by turning off the water supply to the water heater. Partially drain the heater, then remove the down pipe from the pressure relief with a pipe wrench, then remove the pressure relief by turning it counter clockwise with a pipe wrench. Clean any sediment and debris from around the hole. Apply several layers of teflon tape to the threads of the new pressure valve. Install the new valve as tight as possible by hand without the aid of the pipe wrench, then use the wrench to contiue tightning until the outlet of the new valve is oriented correctly Do NOT over tighten, you will break the brass on the valve. Turn the water supply back on and check for leaks, if no leaks reinstall the down pipe to the new relief valve and you're done.

Turn off the power at the breaker box and shut off the cold water supply. Now attach a hose to the boiler drain and either lift the lever on the T&P valve or open a hot water faucet to relieve vacume. Now open the boiler drain a drain the heater. Remove the old T&P valve and wrap the new T&P threads with Teflon Tape. Install the new valve, shut off the boiler drain and turn on the cold water supply. Open up a hot water faucet and do not turn the power back on until you see water running out of the faucet If you fail to do this you will burn out a element if you do. You may now turn the power back on.
Be advised that a T&P valve will open and discharge without being faulty. If your new valve leaks contact me and we'll check it out. Good luck, Tom