Furnace was tripping breaker and not running. Opened breaker box to confirm no loose wires. Furnace wire was in good condition. Thermostat was set to below room temperature. Customer wanted a simpler stat. Installed aa8444 for customer. Furnace would not ignite. Confirmed 120 volts to the igniter. Opened burner compartment to find igniter wire melted and shorted to metal. Swapped out igniter. Tried to position wire where it did not touch anything. Watched it light a couple times and watched 1 heating cycle. Confirmed operation.