WildTurkey;
If it is a self-contained manufactured metal type fireplace (the kind where you do not use real wood), then it is simple. The electricity is supplied via the pilot flame sensor and the switch completes the cicuit to the gas valve. The voltage generated is millivolts. Any standard snap switch will do.
Chances are, the switch may be good. Usually the connections become loose or dirty, causing resistance and effectively cutting the millivolts to a low level and the gas valve will not open.
If it is the real wood type, then the switch is typically used to supply power to the glow or spark gas igniter for the purpose of starting the gas pilot flame which is lit prior to the main gas valve opening.
Hope this helps!
Dave
