A heating and hot water supply system, including: a combustion unit combusting a fuel to generate a combustion gas; a heat exchange unit heating a heat medium and hot water according to heat exchange with the combustion gas; an exhaust unit that exhausting the combustion gas after heat exchange. The heat exchange unit includes a plate type heat exchanger by laminating vertically-upright rectangular plates with gaps, and is configured to heat the heat medium by causing the combustion gas and the heat medium to alternately flow through the gaps. An inlet for the heat medium is provided at lower corner of the plate type heat exchanger, a discharge opening for the heat medium is provided at upper corner farthest from the inlet, and a hot water passage through which hot water flows in the plate type heat exchanger is provided at upper corner above the inlet.

A water heater includes an inner water tube coil and an outer water tube coil separated by a drum baffle. The inner and outer coils extend above a top edge of the drum baffle by at least a full turn of each coil. A flue gas bypass path is defined between a top edge of the drum baffle and a top insulation layer above the inner and outer coils. Flue gases flow radially though the inner coil, up along the drum baffle, through the flue gas bypass path, and downwardly over the outer coil to heat water flowing through the inner and outer coils. The water flows into the outer coil at the bottom of the coil, winds upwardly through the outer coil in countercurrent flow with respect to the flue gases, then down through the inner coil.

A condensate trap apparatus according to the present invention comprises: an inlet hole for inflowing a condensate; a storage space for storing the condensate introduced from the inlet hole; an outlet unit including a discharge hole for discharging the stored condensate from the storage space; and a buoyant body including a closing portion which is convex vertically downward so as to close the discharge hole by being seated on the outlet unit, and a support of a pillar type extending vertically upward from the closing portion.

A water heater includes an inner water tube coil and an outer water tube coil separated by a drum baffle. The inner and outer coils extend above a top edge of the drum baffle by at least a full turn of each coil. A flue gas bypass path is defined between a top edge of the drum baffle and a top insulation layer above the inner and outer coils. Flue gases flow radially though the inner coil, up along the drum baffle, through the flue gas bypass path, and downwardly over the outer coil to heat water flowing through the inner and outer coils. The water flows into the outer coil at the bottom of the coil, winds upwardly through the outer coil in countercurrent flow with respect to the flue gases, then down through the inner coil.

A heating system includes a refrigerant boiler including a heat source for heating a refrigerant from a liquid state to a vapor state, a boiler outlet and a boiler inlet; a heat exchanger in fluid communication with the refrigerant boiler, the heat exchanger including a upper manifold having a heat exchanger inlet coupled to the boiler outlet, a lower manifold having a heat exchanger outlet coupled to the boiler inlet and a plurality of tubes connecting the upper manifold and the lower manifold, wherein refrigerant passes from the upper manifold to the lower manifold via gravity; and a fan moving air over the heat exchanger to define supply air for a space to be heated.

A heating and hot water supply system, including: a combustion unit combusting a fuel to generate a combustion gas; a heat exchange unit heating a heat medium and hot water according to heat exchange with the combustion gas; an exhaust unit that exhausting the combustion gas after heat exchange The heat exchange unit includes a plate type heat exchanger by laminating vertically-upright rectangular plates with gaps, and is configured to heat the heat medium by causing the combustion gas and the heat medium to alternately flow through the gaps An inlet for the heat medium is provided at lower corner of the plate type heat exchanger, a discharge opening for the heat medium is provided at upper corner farthest from the inlet, and a hot water passage through which hot water flows in the plate type heat exchanger is provided at upper corner above the inlet.

In one example embodiment of a hydronic heating system, the system includes at least one condensing boiler and at least one non-condensing boiler, and at least one controller configured for utilizing at least one PID control program to generate at least one signal for controlling firing rates of one or more of the boilers based upon sensed water temperature and temperature setpoint inputs. Depending upon the mode of operation, the at least one PID control program is a first PID control program dedicated to controlling only the at least one condensing boiler, or is a second PID control program dedicated to controlling only the at least one non-condensing boiler, or includes both the first and second PID control programs. Also, outside air temperature serves as a basis for generating the temperature setpoint inputs.

A heating system includes a refrigerant boiler including a heat source for heating a refrigerant from a liquid state to a vapor state, a boiler outlet and a boiler inlet; a heat exchanger in fluid communication with the refrigerant boiler, the heat exchanger including a upper manifold having a heat exchanger inlet coupled to the boiler outlet, a lower manifold having a heat exchanger outlet coupled to the boiler inlet and a plurality of tubes connecting the upper manifold and the lower manifold, wherein refrigerant passes from the upper manifold to the lower manifold via gravity; and a fan moving air over the heat exchanger to define supply air for a space to be heated.

A condensate trap apparatus according to the present invention comprises: an inlet hole for inflowing a condensate; a storage space for storing the condensate introduced from the inlet hole; an outlet unit including a discharge hole for discharging the stored condensate from the storage space; and a buoyant body including a closing portion which is convex vertically downward so as to close the discharge hole by being seated on the outlet unit, and a support of a pillar type extending vertically upward from the closing portion.

Hydronic heating systems, controllers for such systems, and methods of using/operating same are disclosed herein. In one example embodiment, such a system includes at least one condensing boiler and at least one non-condensing boiler, and at least one controller configured for utilizing at least one PID control program to generate at least one signal for controlling firing rates of one or more of the boilers based upon sensed water temperature and temperature setpoint inputs. Depending upon the mode of operation, the at least one PID control program is a first PID control program dedicated to controlling only the at least one condensing boiler, or is a second PID control program dedicated to controlling only the at least one non-condensing boiler, or includes both the first and second PID control programs. Also, outside air temperature serves as a basis for generating the temperature setpoint inputs.