A distribution pump arrangement for a bi-directional hydraulic distribution grid can include a hot conduit control valve in a hot conduit; a first distribution pump having an inlet connected to the hot conduit at a first side of the hot conduit control valve, and an outlet connected to the hot conduit at a second side, opposite the first side, of the hot conduit control valve; a pressure difference determining device arranged beyond the second side of the hot conduit control valve and configured to determine a local pressure difference, ?p, between a local pressure of heat transfer liquid in the hot conduit and a local pressure of heat transfer liquid in the cold conduit; and a controller configured to set the distribution pump arrangement based at least in part on ?p.

A hydronic system and method of use that will maintain normal system operating pressure while also reliably detecting even very small fluid losses in any closed loop fluid heat transfer system is described. The system includes a controller in communication with one or more pressure sensors and optionally one or more temperature sensors that provides one or more notifications when the pressure drops below predetermined levels.

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 fluid transportation network (1) comprises a plurality of parallel zones (Z1, Z2), fed by a common supply line (L), with a regulating zone valve (V1, V2) in each zone (Z1, Z2) for regulating a flow of fluid (.sub.1, .sub.2) through the respective zone (Z1, Z2). A processing unit (RE) receives valve positions (pos.sub.1, pos.sub.2) of the regulating zone valves (V1, V2) and determines and sets an adjusted valve position for a line valve (VE) arranged in the supply line (L), depending on the valve positions (pos.sub.1, pos.sub.2) of the regulating zone valves (V1, V2). A processing unit (RE) further receives a measurement of a total flow of fluid (.sub.tot) through the supply line (L) and determines and sets adjusted valve positions for the regulating zone valves (V1, V2), depending on the measurement of the total flow of fluid (.sub.tot) through the supply line (L).

A heat-pump air-conditioning hot-water supply device includes a first refrigerant passage connecting a compressor and a decompressor, a second refrigerant passage branching from between the compressor and a first solenoid valve and connecting a second solenoid valve, a hot-water supply heat exchanger, and the decompressor, a pressure sensor configured to measure discharge pressure of the compressor, and a control device configured to adjust an operational frequency of the compressor and adjust an opening degree of a valve of the decompressor. The control device is configured to calculate a condensing temperature from the discharge pressure, and perform operation in one of an air conditioning prioritized mode in which a preset operational frequency of the compressor is changed, and an energy saving prioritized mode in which the opening degree of the valve of the decompressor is changed, when the condensing temperature is not lower than a set condensing temperature.

A method of controlling a gas furnace system includes controlling a motor of a draft inducer to increase a speed of the motor in response to a call for heat, receiving pressure signals output by a pressure transducer, receiving signals indicating whether a pressure switch is in a first state or a second state, and determining a first status of the pressure transducer as reliable, unreliable, or questionable at a first time based on the received pressure signals from the pressure transducer, the signals indicating whether the pressure switch is in the first state or the second state, and a first status of the motor of the draft inducer at the first time. Operation of the motor of the draft inducer is stopped when the first status of the pressure transducer indicates that the pressure transducer is unreliable.

A hydronic system and method of use that will maintain normal system operating pressure while also reliably detecting even very small fluid losses in any closed loop fluid heat transfer system is described. The system includes a controller in communication with one or more pressure sensors and optionally one more temperature sensors that provides one or more notifications when the pressure drops below predetermined levels.

An isolation mounting arm for use with an expansion tank has a passageway with a first end portion, a second end portion, and a medial portion located between the first end portion and the second end portion with the drain port located at the terminal end of the second end portion. A first tee is located in the first end portion with oppositely disposed first and second ports. A second tee is located in the second end portion, with oppositely disposed fourth and fifth ports. A first valve member is coupled to the first port, a second valve member is coupled to the second port, and a third valve member is located adjacent to the drain port. An expansion tank is coupled to either the fourth port or the fifth port with a plug coupled to the other port.

A residential and commercial hot water and steam boiler safety system and device that includes at least one hollow pipe, with one plugged or sealed end and a fitting on the other end for connecting the pipe in a substantially vertical mounting position, and at least one two float switch disposed in the pipe and electrically connected in series with a limit switch in the boiler, where the pipe is adopted for the flow and accumulation of water, so that float switch activates as the pipe fills with water and shuts off the boiler by turning off the gas valve, promoting safer boiler and steam boiler operation. Additional float switches positioned above or below in the hollow pipe may provide additional functions, such as a warning light and sound to the owner, or a notification via a telephone or cell phone system or through the home network or Wi-Fi system.

A hydronic heating system that may depend on pressure in the system for smooth operation. The pressure may be monitored. Pressure in the system may indicate health of the heating system. Certain pressures or variations of pressures may indicate one or more conditions in the system which may be good or adverse. An example of an adverse condition may be leakage of fluid from the system. Analyses of pressures detected in the heating system may be performed by a computer programmed to indicate conditions of the system that are reflected by the detected pressures.