Abstract: A low NO.sub.x combustion system for reducing the production of nitrogen oxides in its emissions by using a low NO.sub.x adapter assembly in conjunction with a heat exchanger and a standard burner. The low NO.sub.x adapter assembly includes a low NO.sub.x manifold housing coupled between the heat exchanger and the burner, a flue gas recirculating fan coupled to the stack of the heat exchanger and the low NO.sub.x manifold housing and an operating control mechanism for controlling and regulating the primary air, the recirculated flue gas and the fuel to the burner and the low NO.sub.x manifold housing. NO.sub.x is reduced by supplying recirculated flue gas and a secondary fuel into the combustion chamber of the heat exchanger adjacent the outlet end of the burner via the low NO.sub.x manifold housing.

Abstract: A hinge assembly which allows pivotal movement between first and second panels of at least 90.degree. and which allows separation of the two panels anywhere along the pivotal movement. The assembly has a hinge member formed of a single piece of bent sheet metal. The hinge assembly comprises a first portion located on the first panel, a lip extending substantially perpendicularly from the first portion, and a hinge member rigidly coupled to the first panel and having an intermediate portion extending substantially perpendicularly from the first panel and a leg extending substantially perpendicularly from the intermediate portion towards the lip. The distal edge of the lip and the distal edge of the leg define a slot which receives a second portion located on the second panel to thereby pivotally couple the first and second panels.

Abstract: A hinge assembly which allows pivotal movement between first and second panels of 90.degree. and which allows separation of the two panels. The hinge assembly comprises a first portion located on the first panel and having a lip extending substantially perpendicularly therefrom, a second portion located on the second panel, and a hinge member rigidly coupled to the second panel and having an arm defining a slot with the second portion, which slot receives the lip therein when the first and second panels are substantially perpendicular and receives the first portion therein when the first and second panels are substantially parallel.