Hello: My son bought a new to him house, and we are doing the rehab of it, which is just about complete. Today, we drained about 10 gallons out of it, refilled it and attempted to fire it up. 8 am not sure if it is called a direct vent or a power vent, but there is a blower on the top of the water heater that expels the exhaust out the side wall. In any case, we turn it on, the piezo electric spark ticks, and the pilot lights and stays lit. However, the burner never lights. The exhaust smells of natural gas. Not sure how to attach pictures . It is a Branford White Model number M1TW50S6FBN. It does not have a thermocouple. If someone can direct me how to attach pictures, I would appreciate it. In the meantime, any ideas of what to check?