A thermodynamic boiler for exchanging (providing or drawing) heat with a heating circuit includes a thermal compressor. The thermal compressor acts on a compressible fluid and includes at least one compression stage, with an alternating bi-directional piston separating a first chamber and a second chamber, and a first fuel burner forming a heat source coupled to the first chamber. The thermal compressor uses the heating circuit as a cold source coupled to the second chamber and forms the compression function of a reversible heat pump type loop.

A combustion device includes a combustion control section which controls combustion in the combustion device; a setting section operated to set information indicating whether or not a plurality of combustion devices are in a common vent discharge state; and a memory section which stores therein connection configurations with the other combustion control sections to which the combustion control section is communicatively connected, and the combustion control section determines whether or not the combustion control section can communicate with a linkage control section or the other combustion control sections, and inhibits combustion in the combustion device to which the combustion control section belongs, in a case where the combustion control section determines that the combustion control section cannot communicate with the linkage control section or at least one of the other combustion control sections and the common vent discharge state is set by the setting section.

A control system is provided for a modulated heating system including a plurality of modulating water heaters, which may be modulating boilers. A deadband control scheme provides for reduced cycling of the modulating heater when total system heat demand falls between the maximum output of one heater and the sum of the maximum output of that one point and the minimum firing point of the next subsequent heater. Condensation of flue gas products is prevented by monitoring flue exhaust temperature for each heater and controlling the modulation of each heater to maintain a minimum heater output sufficiently high to prevent condensation of flue gas products from that heater. Rapid reaction to changes in system heat demand is provided by sensing changes in flow rate in a primary loop of the system and anticipating resulting changes in temperature thus allowing for change in heater output prior to the time the change in flow rate has fully impacted system temperature.

A plurality of water heaters are connected in parallel with respect to a hot water supply path, and each of the plurality of water heaters has an exhaust path connected to an exhaust path assembly. Each of a plurality of sensing units is configured to be shifted from an electrically conducting state to an electrically non-conducting state when each of the plurality of sensing units senses an abnormal condition about air supply or exhaust. A series circuit of the plurality of sensing units is electrically connected in series to a resistance element between the power supply line and the ground line. The controller is configured to monitor an abnormal condition about air supply or exhaust based on a voltage on a node between the series circuit and the resistance element.

A combined heating system comprising a first heating subsystem including a first fluid conductor, a first heating unit adapted to heat a first fluid and output the first fluid at the outlet of the first fluid conductor, and a fluid mover adapted to move the first fluid through the first heating unit, a second heating subsystem including a second fluid conductor adapted to receive a second fluid, a third fluid conductor, a second heating unit adapted to heat the second fluid and output the heated second fluid in the third fluid conductor, a fluid mover adapted to move the second fluid from the outlet of the third fluid conductor to the inlet of the second fluid conductor, at least one heat exchanger operably connected to a downstream location of the first heating unit and a fourth fluid conductor connecting the second fluid conductor and the third fluid conductor.

A low pressure drop water heating system comprising a cold side conductor having a receiving end and a closed end; a hot side conductor having an exit end and a closed end; a pump; a bypass conductor having a first end and a second end, wherein the first end is adapted to the receiving end and the second end is adapted to the exit end; at least one heat exchanger having a flow valve; a heat exchanger inlet temperature sensor disposed on the inlet of one of the at least one heat exchanger; an outlet temperature sensor disposed at an outlet of the at least one heat exchanger closest to the exit end; a system outlet temperature sensor disposed on the exit end and a system inlet temperature sensor disposed on the receiving end.

A control system is provided for a modulated heating system including a plurality of modulating water heaters, which may be modulating boilers. A deadband control scheme provides for reduced cycling of the modulating heater when total system heat demand falls between the maximum output of one heater and the sum of the maximum output of that one point and the minimum firing point of the next subsequent heater. Condensation of flue gas products is prevented by monitoring flue exhaust temperature for each heater and controlling the modulation of each heater to maintain a minimum heater output sufficiently high to prevent condensation of flue gas products from that heater. Rapid reaction to changes in system heat demand is provided by sensing changes in flow rate in a primary loop of the system and anticipating resulting changes in temperature thus allowing for change in heater output prior to the time the change in flow rate has fully impacted system temperature.

A thermodynamic boiler for exchanging (providing or drawing) heat with a heating circuit includes a thermal compressor. The thermal compressor acts on a compressible fluid and includes at least one compression stage, with an alternating bi-directional piston separating a first chamber and a second chamber, and a first fuel burner forming a heat source coupled to the first chamber. The thermal compressor uses the heating circuit as a cold source coupled to the second chamber and forms the compression function of a reversible heat pump type loop,

An on-demand high volume capable fluid heating system for supplying a total heating power at a turndown ratio and a total flowrate of a fluid supply, the fluid heating system comprising a plurality of heat exchangers fluidly connected in parallel, each of the plurality of heat exchangers comprising: a fluid conductor, wherein each of the plurality of heat exchangers contributes to the total heating power and a portion of the total flowrate of the fluid supply through the fluid conductor; an inlet conductor configured to connect the fluid supply to the plurality of heat exchangers; an outlet conductor configured for receiving the fluid supply downstream of the plurality of heat exchangers; an auxiliary conductor connecting the inlet conductor at a first location and the outlet conductor, the auxiliary conductor comprising a modulating valve; and a pump disposed downstream from the first location on the inlet conductor.

A plurality of water heaters are connected in parallel with respect to a hot water supply path, and each of the plurality of water heaters has an exhaust path connected to an exhaust path assembly. Each of a plurality of sensing units is configured to be shifted from an electrically conducting state to an electrically non-conducting state when each of the plurality of sensing units senses an abnormal condition about air supply or exhaust. A series circuit of the plurality of sensing units is electrically connected in series to a resistance element between the power supply line and the ground line. The controller is configured to monitor an abnormal condition about air supply or exhaust based on a voltage on a node between the series circuit and the resistance element.