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.

An outdoor-use heating mat includes a mat body, a water container, a substance container, and a first circulating pump. The water container is disposed in the mat body. The water container has a first inlet and a first outlet. The substance container is configured to hold a substance that can chemically react with water and release thermal energy. The substance container has a second inlet, a second outlet, and a normally closed feed port. Two ends of the first circulating pump are in communication with the first outlet and the second inlet, respectively. The second outlet is in communication with the first inlet. The outdoor-use heating mat can be heated, easy to carry.

The disclosed technology includes systems and methods for operating a fluid heating device comprising a heat pump and an electric heating element. The disclosed technology can include a system and method that can receive current data from a current sensor and temperature data from a temperature sensor, determine whether the current is greater than or equal to a threshold current and whether the temperature is greater than or equal to a threshold temperature, and output a control signal to heat the fluid using the heat pump only or the electric heating element only based on the current data and the temperature data.

A device that includes a pressure sensor that adds dynamic pressure sensing capability to a furnace. In some examples the device may include a relay and other circuitry to replace the single-setpoint pressure switch used to sense the operation of an inducer fan. The pressure sensor may measure the pressure from the inducer fan and send a signal to the other circuitry, such as a microcontroller. The other circuitry may determine when the pressure from the inducer fan reaches a predetermined threshold and allow the main gas valve of the furnace to open. The other circuitry may be configured to set the pressure sensor to a variety of predetermined pressure thresholds, and thereby replace multiple pressure switches. In some examples, the other circuitry may record pressure values received from the pressure sensor over time and provide performance data, as well as other signals or indicators.

A heat pump may include a compressor configured to compress a refrigerant, a first temperature sensor configured to detect an outdoor temperature, a second temperature sensor provided in heating pipes connected to a heating device, and a controller. Based on a first sensing value of the first temperature sensor, the controller may be configured to control a compressor, control power to a boiler, and/or calculate an expected efficiency of the heat pump. Based on the expected efficiency and/or a second sensing value of a second temperature sensor, the controller may be configured to control power to the boiler.

The disclosed technology includes a variable refrigerant flow (VRF) conditioning system including a single outdoor unit and a VRF path extending between the single outdoor unit and a plurality of terminals. The plurality of terminals can include a first terminal configured to condition air of an interior room and a second terminal configured to heat or cool a liquid. The VRF system can provide heating or cooling of air in different rooms or zones within a building or home while also providing heating or cooling of water. In response to a demand for heating or cooling at each terminal, the VRF system can vary the supply of refrigerant to each terminal, such that efficient and precise temperature regulation of air and liquid can be provided.

A residential and commercial sewerage and water drainage safety system and device that includes at least one hollow pipe, with a plugged or sealed top end and a fitting on the bottom end for connecting the pipe in a substantially vertical mounting position into the sewerage or water drainage system, and at least one float switch disposed in the pipe and electrically connected with a water shut off valve, where the pipe is adopted for the flow and accumulation of fluid, so that the float switch activates as the pipe fills with fluid and shuts off the water valve, promoting safer sewerage and water drainage system 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.

Techniques for an electronic device to perform power-stealing techniques to harvest energy from a power-control circuit to power components of the electronic device. In some examples, the electronic device may be connected in the power-control circuit between a power supply and a relay that is selectively configured to activate a power load. According to the techniques described herein, the electronic device may include voltage-drop circuitry that is connected in the power-control circuit such that a voltage drop is produced across electrical components of the electronic device while the relay is in the activated, or triggered, state. In this way, the electronic device may perform power-stealing from the power-control circuit while the relay is maintained in the activated state.

A method and an arrangement for recovering heat from flue gas of a boiler (10). The method comprises passing the flue gas (G) of the boiler though a flue gas cooling unit (1), cooling the flue gas (G) by transferring heat from the flue gas (G) into a circulation (3) of a flue gas cooling liquid (CL), transferring heat energy of said flue gas cooling liquid (CL) into a heat pump (2), and arranging the heat pump (2) for receiving heat energy also from a circulation arrangement (8) of a district cooling system. The heat pump (2) is coupled to a circulation arrangement (6) of a district heating system, wherein the method further comprises transferring in the heat pump (2) heat energy (H) received from said cooling liquid (CL) and from said circulation arrangement (8) of district cooling system into said circulation arrangement (6) of district heating system, for lowering the temperature of said flue gas cooling liquid (CL) and cooling fluid of said district cooling system, and raising the temperature of heating fluid of said district heating system.

Dispensing of hot water having an adjustable temperature by way of a water outlet fitting that can be installed on a sink. This is achieved by a continuous flow heater and a measured value sensor arranged in a water inlet of the water outlet fitting as the hot water heater. The measured value sensor detects a measurement variable with regard to water flowing through the continuous flow heater (10). The water dispensing device has a control unit, which is designed to regulate a flow rate through the continuous flow heater as a function of measured values of the measured value sensor in order to adjust the temperature of the hot water.