Abstract: A method of protecting a single-stage furnace in a multi-zone system includes monitoring a temperature of each zone of a plurality of zones, determining if the temperature of at least one zone of the plurality of zones is less than a threshold temperature, powering on the HVAC system to satisfy a heating demand of the zone having a temperature less than the threshold temperature, monitoring an outlet temperature of the single-stage furnace, determining if the outlet temperature is greater than an outlet temperature threshold, and responsive to a determination that the outlet temperature is greater than the outlet temperature threshold, modulating a gas valve to reduce a flow of gas to the single-stage furnace.

Abstract: A multi-position furnace is provided that can be positioned for downflow operation, upflow operation, left horizontal flow operation, or right horizontal flow operation without major modifications in the field. The furnace includes a multi-position condensate draining system which facilitates draining of condensate fluid regardless of the orientation of the furnace. The condensate draining system includes a header box and an exhaust manifold, each of which includes a number of drain ports that allow fluid condensing from combustion gasses to be drained regardless of furnace orientation. A trap is configured for attachment to the furnace in any one of four different positions, and receives condensate fluid from the header box and from the exhaust manifold. An air intake manifold is specially configured to maintain a low profile, thereby facilitating use of the multi-position condensate draining system.

Abstract: In a gas-burning apparatus, such as a furnace, a device for reducing NOx emissions includes a cup member mounted proximate to an inlet to a combustion chamber of the apparatus and a perforate member attached to the cup member and located in the combustion chamber at a predetermined distance inwardly from the inlet. The perforate member has a plurality of holes to define a mesh pattern through which the flame and other products of combustion are constrained to pass within the combustion chamber. The perforate member acts as a heat sink to reduce the flame temperature, thereby inhibiting NOx production.

Abstract: In a gas-burning apparatus, such as a furnace, a device for reducing NOx emissions includes a cup member mounted proximate to an inlet to a combustion chamber of the apparatus and a perforate member attached to the cup member and located in the combustion chamber at a predetermined distance inwardly from the inlet. The perforate member has a plurality of holes to define a mesh pattern through which the flame and other products of combustion are constrained to pass within the combustion chamber. The perforate member acts as a heat sink to reduce the flame temperature, thereby inhibiting NOx production.