We have a gas fire that is started by a switch located on the adjacent wall.Recently the fire does not start when the switch is turned on. I replaced the thermo couple unit and also installed a new valve unit but the only way the fire will open the gas valve and light is if I bridge the terminals between the thermocouple unit with a small battery introducing a voltage to operate the valve. I did replace the wiring from the old thermo couple to the switch, could I have used a wire that is a too heavy gage for the thermo produced voltage to work the valve? If so where can I find the correct wire needed?