Can the nat gas contol valve be easily replaced... and can the control valve be replaced with one other than the brand it was manufactured with?

Hi Amaron...

Yup! The gas contol can be easily swapped out by:

1) shutting off the gas
2) removing the thermocouple
3) removing the pilot tubing
4) removing the main burner tube
5) draining the water heater
6) spinning the gas valve out counterclockwise.
7) and finally installing a new gas valve.

I would recommend that you stick with the same manufacturer if possible, or at least get a universal fit gas valve that matches up exactly with your old one.

Any questions just let us know, OK?

Mark

Mark gave you excellent instructions.
May I suggest the next time you post lose the caps. We don't yell at each other in here. Thanks, Tom