A water heater that includes a water container, a combustion chamber, adjacent the water container, having at least one inlet to admit air and extraneous fumes into the combustion chamber, at least one inlet comprising a metal plate through which pass a plurality of ports, the ports comprising a plurality of slots and holes, each slot having a quenching distance and each hole having a quenching distance and being capable of confining ignition and combustion of said extraneous fumes within the combustion chamber; and a burner associated with the combustion chamber and arranged to combust fuel to heat water in the container.