A high efficiency downfired gas water heater is provided which has a tank for storing water to be heated, a combustion chamber extending downwardly through a top end of the tank, and a gas burner operative to create hot combustion products within the combustion chamber. At the bottom end of the tank is a transfer chamber coupled to an external discharge conduit and to a single pass heat exchanger, in the form of multiple flue tubes. extending vertically through the tank and connected to the combustion chamber. In one embodiment of the water heater the burner is a power burner which forces the combustion products sequentially through the combustion chamber, heat exchanger, transfer chamber and discharge conduit. In another embodiment of the water heater a draft inducer fan is used to draw the combustion products through this path from the combustion chamber.

A system and method is described for a heater box or compartment within a gas furnace or other HVAC cabinet. The compartment can house drain hoses, drain traps, and other components used to collect and dispose of condensate. The compartment can comprise heating elements or thermostatic switches to assist in preventing the freezing of condensate.

The purpose of the present invention is to provide a condensing boiler employing an eco-friendly evaporation device, in which condensed water generated in a latent heat exchanger is removed by using the evaporation device, so that the condensing boiler can be installed in a site without a processing facility for discharging condensed water and contribute to energy saving. For implementation thereof, the present invention comprises: a blower (110) for supplying a supply-air; a sensible heat exchanger (140) for absorbing combustion sensible heat generated in a combustion chamber (130) by combustion by a burner (120); a latent heat exchanger (150) for absorbing latent heat of steam included in combustion gas which has finished heat exchange in the heat sensible exchanger (140); and an evaporation device (160) which absorbs condensed water generated in the latent heat exchanger (150), and has an evaporation type humidifier (161) for evaporating and removing the absorbed condensed water by using air supplied from the blower (110).

A non-return valve having an accumulation damper movable relative to a housing and shaped like a bowl to accumulate condensate running down from the chimney. The non-return valve has a smaller floating damper made of a material having a density less than water for resting against the accumulation damper when the appliance is in standstill and sealing the drainage holes in the accumulation damper when the condensate accumulation is below a threshold. Once condensate accumulates in the accumulation damper beyond the threshold, the floating damper is buoyed by the condensate thereby breaking the seal with the drainage holes and permitting the condensate to drain through drainage holes in the accumulation damper. When the appliance is operational, exhaust from the appliance lifts the floating damper and, in some cases, the accumulation damper also, to permit exhaust of combustion gases up the chimney.

A water heater includes: a burner; a heat exchanger; a fan for supplying air to the burner and emitting combustion gas having passed through the heat exchanger to outside of the water heater; and a drainage water discharge path connected to the heat exchanger. The drainage water discharge path has a water-sealing structure that is water-sealed by drainage water. The water heater further includes a control unit: having a water-seal determination unit giving permission that the water heater can operate in a normal mode based on a condition that the drainage water discharge path has been water-sealed; and issuing an instruction to cause the burner to intermittently operate for a time period until the water-seal determination unit gives the permission.

An alternative-fuel gas orifice, a gas furnace configured to employ the same and a method of designing a gas orifice. In one embodiment, the gas orifice includes: (1) a body having an aperture extending therethrough and including: (1a) a metering neck having a cross-sectional area such that a given flow rate of a gas is established when the gas is delivered to the gas orifice at a given alternative-fuel delivery pressure and (1b) a diffuser having a cross-sectional area larger than the cross-sectional area of the metering neck and a length such that the gas achieves a substantially laminar flow before exiting the diffuser.

A latent heat recovery heat exchanger includes a heat exchange portion and a case. The heat exchange portion includes a plurality of heat transfer plates layered on one another. The case accommodates the plurality of heat transfer plates of the heat exchange portion. The heat exchange portion includes a front plate portion provided as an outermost layer of the heat exchange portion. The front plate portion of the heat exchange portion forms a part of the case.

A conduit fitting for an exhaust duct includes a conduit and a condensate trap. The conduit fitting defines an interior space partitioned into an upper conduit and a lower condensate reservoir. The condensate reservoir can be configured to contain a neutralizing agent for neutralizing acidic condensate prior to it exiting the reservoir.

An integrated pressure condensing boiler is provided which relates to the technical field of boilers. The integrated pressure condensing boiler includes a pressure-bearing housing, a heat-exchange furnace arranged in the pressure-bearing housing, a combustion chamber communicating with the heat-exchange furnace and cooling tube groups fixed in the heat-exchange furnace. Heat-exchange medium flows from bottom to top in the pressure-bearing housing and in the cooling tube groups, and exchanges heat with high-temperature flue gas flowing from top to bottom in the heat-exchange furnace, thus achieving a counterflow heat exchanging. The heat-exchange furnace includes a multi-stage heat-exchange chamber with each heat-exchange chamber being cylindrical. The heat-exchange chambers are arranged in sequence from top to bottom to achieve a flue gas diffusing manner that high-temperature flue gas diffuses from center part to periphery and then gathers from periphery to center part.

A condensate drain system for a heating, ventilation, and/or air conditioning (HVAC) system includes a heat exchanger having a plurality of tubes configured to receive ambient air and fluidly coupled to a drain via a conduit, a valve positioned along the conduit between the plurality of tubes and the drain, where the valve is configured to enable a flow of condensate from within the plurality of tubes toward the drain in an open position and the block the flow in a closed position, and a controller configured to adjust a position of the valve based on feedback indicative of an operational state of the HVAC system.