How do I release pressure valve in H2O heater?

First make sure the electricity and propane are off.

There are a couple of things you can do to relieve the pressure in the WH.  You can simply turn off the pump or disconnect the city water and then turn on the hot water in the kitchen sink until it quits running.  The other thing you can do is lift the little lever on the thing on the outside of the water heater, on the same face of the WH that the anode is on.  This thing looks sort of like the anode but, from memory, sticks out a little more, has an outlet on it, and a little spring-loaded lever that you can lift manually, easily.  This is the pressure relief valve, that's main job is to relieve the pressure on the WH automatically if the pressure gets too high.  As I said, you can also work it manually.  It's meant to prevent your water heater from blowing up if something fails and the propane or electricity fails to turn off when it should and the water in the WH starts to boil.  (Ka-boom!) 

It's always a good idea to lift that lever before working on the WH, but you need to do all of the other steps too anyway.  Turn off the pump and open the hot (and cold) faucets at the sink and leave them open.  After that the pressure relief valve is just an added safety feature that you don't have to use.

Glad you're okay.  Some lessons are more expensive than others!

TT

Thank you TT & John! I located the pressure valve & lever. My hand is healing nicely.  I appreciate all the good info!