A process air unit (20) for heating a process air (21) for a workpiece processing system comprises a process air duct (22) through which a process air (21) can flow, a combustion chamber (30) for burning a combustion air, which is overflowed by the process air (21) in the process air duct (22) and thereby transfers heat to the process air (21), and a tube bundle arrangement (35) connected to the combustion chamber, which comprises at least one tube bundle (36) having a plurality of tubes (38) through which the flue gas (34) from the combustion chamber (30) can flow. The plurality of tubes (38) of the at least one tube bundle (36) is oriented in the process air duct (22) transversely to the process air flow direction, so that they are overflowed by the process air (21) and thereby transfer heat from the flue gas (34) to the process air (21), and the tube bundle arrangement (35) is arranged, with respect to the process air flow direction, upstream of the combustion chamber (30) in the process air duct (22) in order to achieve increased energy efficiency.

An air conditioning system includes a heat pump section performing indoor air-warming by using a vapor-compression refrigeration cycle, a separate heat source section performing indoor air-warming by using a heat source separate from the heat pump section, and a control unit configured to control actions of the heat pump section and the separate heat source section. When a heat pump air-warming operation is being performed, and when a first switching condition is met, the control unit switches from the heat pump air-warming operation to a separate heat source air-warming operation. The first switching condition is that an outside air temperature reaches a first switching outside air temperature and an air-warming capability of the heat pump section reaches an upper limit.

This invention relates to a heater. A combustion air blower feeds combustion air to a burner device. The burner device burns a gas-air mixture from the combustion air and a fuel and serves for heating air. A circulating air blower discharges heated air from the heater. A control device acts on at least one component of the heater, wherein a night mode parameter set associated with an operation of the heater in a night mode and a default parameter set are stored in a data storage device. After an activation of the night mode, the control device accesses the night mode parameter set and uses the same for acting on the component. The night mode parameter set effects a reduction of background noise generated by the heater.

System (200) for heating a structure (10), wherein the system comprises a first heat pump (210), arranged to transfer heat to a first hot-side external liquid from a cold-side external liquid circulating in the ground (20) or a water body (21); and a second heat pump (220), arranged to transfer heat to a second hot-side external liquid; wherein the system is arranged to heat the structure (10) via heat exchange with at least the first external liquid. The air-to-liquid heat pump uses carbon dioxide as an internal-loop heat medium, and the system comprises a third heat exchanger (230) being arranged to, cool the internal-loop heat medium by heat exchange with the cold-side external liquid, the cooling of the internal-loop heat medium being to a temperature of less than a critical point (CP) of the internal-loop heat medium. The invention also relates to a method.

System (200) for heating a structure (10), wherein the system comprises a first heat pump (210), arranged to transfer heat to a first hot-side external liquid from a cold-side external liquid circulating in the ground (20) or a water body (21); and a second heat pump (220), arranged to transfer heat to a second hot-side external liquid; wherein the system is arranged to heat the structure (10) via heat exchange with at least the first external liquid. The air-to-liquid heat pump uses carbon dioxide as an internal-loop heat medium, and the system comprises a third heat exchanger (230) being arranged to, cool the internal-loop heat medium by heat exchange with the cold-side external liquid, the cooling of the internal-loop heat medium being to a temperature of less than a critical point (CP) of the internal-loop heat medium. The invention also relates to a method.

An aerosol-generating device is provided, including: an air inlet configured to allow ambient air to enter the aerosol-generating device; an airflow channel fluidly connected with the air inlet; a filter element arranged in the airflow channel adjacent the air inlet and configured to filter the ambient air entering the aerosol-generating device; and a heating element arranged at the airflow channel adjacent the air inlet and configured to heat the ambient air entering the aerosol-generating device, the heating element being further configured to heat the ambient air entering the aerosol-generating device to a temperature of between 15 C. and 35 C.

An aerosol-generating device is provided, including: an air inlet configured to allow ambient air to enter the aerosol-generating device; an airflow channel fluidly connected with the air inlet; a filter element arranged in the airflow channel adjacent the air inlet and configured to filter the ambient air entering the aerosol-generating device; and a heating element arranged at the airflow channel adjacent the air inlet and configured to heat the ambient air entering the aerosol-generating device, the heating element being further configured to heat the ambient air entering the aerosol-generating device to a temperature of between 15 C. and 35 C.

A heating control device including input/output ports, a memory operable to store smoke output thresholds, and a microprocessor. The microprocessor is configured to transmit a first electrical signal to operate an air circulation fan at a first speed and a heating unit in a first configuration to burn a lubricant at a first temperature where less than all of the burners are active. The microprocessor is further configured to obtain a smoke output measurement for the first temperature, compare the smoke output measurement to the smoke output threshold, and transmit a second electrical signal to transition the air circulation fan to a second speed to burn the lubricant at a second temperature that is greater than the first temperature when the smoke output measurement is less than the smoke output threshold and is less than the first temperature when the smoke output measurement is greater than the smoke output threshold.

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 heating control device comprising input/output ports, a memory, and a microprocessor. The microprocessor is configured to transmit a first electrical signal to operate an air circulation fan at a first speed and a heating unit in a first configuration to achieve a first temperature rise where less than all of the burners are active. The microprocessor is further configured to obtain a return air temperature, obtain a room air temperature, and determine a temperature difference between the return air temperature and the room air temperature. The microprocessor is further configured to compare the temperature difference to a temperature rise threshold and transmit a second electrical signal to transition the air circulation fan from the first speed to a second speed to achieve a second temperature rise that is less than the first temperature rise when the temperature difference is greater than the temperature rise threshold.