As long as the burner is lit on the hot water heater you shouldn't have a problem. If the light is not functioning on the switch then you can double check the 12V power on the back. Assuming you're getting power, it is a problem with the switch itself. For a replacement, you can use the Double-Panel On/Off Switch for Dometic Gas / Electric Combination Water Heaters - White # AT91230. view full answer...