According to various aspects, exemplary embodiments are disclosed of blow through direct fired heaters including evaporator coils and/or energy recovery ventilation.

A heating unit for a heating, ventilation and/or air conditioning (HVAC) system may have a first airflow path through the heating unit, a second airflow path through the heating unit, and a heater assembly having a first heating coil positioned within the first airflow path, a second heating coil positioned within the second airflow path, and a coil divider separating the first heating coil and the second heating coil.

A heating control method includes determining a first speed for an air circulation fan that corresponds with a temperature set point using a temperature map that maps temperatures to speeds of the air circulation fan and operating the air circulation fan at the first speed and a heating unit in a first configuration with at least one active burner from a plurality of burners where less than all of the burners are active when the heating unit is in the first configuration. The method further includes measuring a first temperature while operating the air circulation fan at the first speed, determining a temperature difference between the first temperature and the temperature set point, comparing the temperature difference to a temperature difference threshold, and updating the temperature map to map the first speed to the first temperature when the temperature difference is greater than the temperature difference threshold.

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.

The disclosed technology relates to a solar water heating system including a tank configured to store heat transfer fluid, a solar collector in fluid communication with the tank, and a pump system in fluid communication with the tank and the solar collector. The pump system can include a first pump, a second pump, and a valve assembly. The valve assembly can direct the heat transfer fluid from an outlet of the first pump to the solar collector when the first pump is operating and can direct the heat transfer fluid from an outlet of the second pump to the solar collector when the second pump is operating. The first pump and the second pump can transfer the heat transfer fluid from the solar collector back to the tank when the first pump and the second pump are not operating.

A combined heat and power (CHP) system is installed with a power lock-out feature preventing flow of heated working fluid to an expander driving a generator generating electrical power until installation by a licensed person is completed, whereby heat can be provided to a building substantially immediately after installation of the CHP system, while power generation can be deferred until convenient.

The present invention relates to a method of controlling a gas furnace that performs heating operation according to a heating signal formed of one of a weak heating signal and a strong heating signal. The method includes: (a) receiving the heating signal; (b) determining whether the heating signal is the weak heating signal or the strong heating signal; (c) calculating a certain weak heating capacity smaller than a maximum heating capacity of the gas furnace, when the heating signal is the weak heating signal; and (d) operating a weak heating of the gas furnace with the calculated certain weak heating capacity, wherein the step (c) includes calculating the weak heating capacity according to a difference between a temperature of air (hereinafter, an intake air temperature) sucked into the gas furnace and a reference temperature set based on the intake air temperature.

A zone controller works with a modulating unit comprising memory storing an instruction set and data related to thermostats, a plurality of duty cycles for a plurality of zones, a plurality of time periods for the plurality of zones, and a maximum zone load. A processor is operative to provide a modulating signal to the modulating unit based on the maximum zone load. The modulating signal determines operation of the modulating boiler and the maximum zone load based on the plurality of duty cycles, time periods, and data related to thermostats. The zone controller may be further operative to: calculate a first duty cycle for the first zone based on a first time period; calculate a second duty cycle for the second zone based on a second time period; and determine a maximum zone load, which is a greater of the first duty cycle and the second duty cycle.

The objective of the present invention is to provide a boiler system for bath heating and hot water that is capable of performing heating and hot water preheating by using a single circulation pump for both without the need to separately include a circulation pump for heating and a circulation pump for hot water preheating. In order to achieve the above objective, the present invention provides a boiler system for both heating and hot water, comprising: a heat exchanging unit; a heating water channel connected between the heat exchanging unit and a place to be heated; a tap water supply pipe for supplying tap water to the heat exchanging unit; a hot water supply pipe for supplying hot water to a place requiring hot water from the heat exchanging unit; a hot water recirculation channel connected to the hot water supply pipe at a first branch point branched from one side of the heating water channel; a hot water bypass channel connected from the second branch point branched from the other side of the heating water channel to the tap water supply pipe; and a circulation pump disposed between the first branch point and the second branch point.

Embodiments of the present disclosure are directed to a furnace that includes a blower configured to operate to force a fluid through the furnace, a motor having a rated speed, in which the motor is coupled to and configured to actuate the blower, and a controller configured to receive data indicative of an operating characteristic of the furnace and regulate operation of the motor to be at or below an operational speed limit. The controller is configured to set the operational speed limit based on the data indicative of the operating characteristic of the furnace, such that the operational speed limit is less than or equal to the rated speed of the motor.