What should the bladder air pressure be set at in a residential pressure tank

When you say residential, it makes me think city water supply. Are you on city water, or on a private well? On a well(pump) system, the bladder should be set at 2psi below cut in of pump pressure switch. Let us know more about your setup and we will try to help.

112, when you set the pressure in the tank, make sure you do it with the system off and all pressure drained off through a nearby faucet. MGD is exactly correct in that the pressure should be set to 2# below cut in pressure.

112, when you set the pressure in the tank, make sure you do it with the system off and all pressure drained off through a nearby faucet. MGD is exactly correct in that the pressure should be set to 2# below cutin pressure.

What do you mean by make sure the system is off?

Power off to the pump, and all the pressure drained off the system. This is the only way to get an accurate reading of the pressure tank pre-charge. If you don't kill the pump and drain the system pressure, you will just read what the system pressure is, not what the pre-charge of the tank is.