DUCTED SECONDARY AIR FUEL-FIRED WATER HEATER LDO DETECTION

摘要

A radiant burner within the combustion chamber of a fuel-fired water heater is supplied with primary and secondary combustion air from outside the combusti on chamber. A flame-holding mesh section of the burner is protected from becomi ng unacceptabLy clogged by particulate matter in the primary combustion air by causing the incoming secondary combustion air to flow sequentially through a finer mesh section and a tapered duct which increases the velocity of the secondary combustion air before causing it to impinge upon and cool a temperature sensor connecte d to a controller. Clogging of the finer mesh section decreases the cooling of the temperature sensor, thereby causing the controller to terminate operation of the burner before it becomes unacceptably clogged.