High pressure heater, is a hybrid heater that heats the feedwater after the high-pressure feedwater pump, used to increase the feedwater temperature and improve economic efficiency.

Low pressure heater, is a device that uses steam that has done some acting in a steam turbine to draw it into the heater to heat the feedwater, increase the temperature of the water, reduce the amount of steam discharged from the turbine to the condenser, reduce energy loss, and improve the cycle efficiency of the thermal system.

The working mode of high pressure and low pressure heaters is basically similar. The heater is filled with small tubes, and the boiler feed water and condensate water pass through the tubes. The steam extracted from each section of the turbine outside the tubes is heat exchanged to increase the temperature of the feed water and condensate water respectively. The extracted steam is condensed into water and becomes drain water. The drain water of the high-pressure heater is usually sent to the high-pressure deaerator, and the drain water of the low-pressure heater is usually pumped to the condenser through a drain pump.