Any hints on replacing a T&P valve on an A O Smilth water heater. I'm assuming you have to shut off water to the unit. Then do you simply unscrew, clean threads in wall of heater and replace with teflon tape on threads of new valve? Thanks for any heads up.

You can do it one of two ways. Safest bet is to shut water off to heater, shut power off to heater(or turn gas valve to pilot) then drain the heater down to where the water level is below the relief valve port. Then simply unthread old valve, telflon or pipe dope new valve, install new valve, turn water back on(make sure to open hot water fuacet somewhere in the house so air can bleed out of water heater, once water starts coming out of fuacet at a regular rate, shut off faucet). Turn power or gas valve back on, and your all set.]

Second way is to do it on the fly. Shut water off, open a hot fuacet until pressure is relieved, close fuacet, make sure the new vavle is already tefloned or doped Then unthread the old valve, and (as quickly as possible) install the new one. Turn water back on, and go open a hot faucet for a minute or so just to make sure any air gets out of tank. Good idea to were some gloves and have some towels handy for changing on the fly, as you will get a litte hot water between exchange. Good luck and let us know how things go for you.

One other very important thing to do(especially if changing it on the fly) is to make sure you have the correct replacement valve. There are different lengths of shanks(long shank, short shank), and if you have the wrong one it may not be long enough to thread in.

Many thanks! I'm off for a new valve!

Please let me know how things work out. Good luck, should go smoothly.