How Does Air to Water Heat Pump Work

  • By:Heyi
  • Date:2021/11/20

How heat pumps work?

  • The compressor of the air-energy heat pump water heater converts the low-temperature and low-pressure gaseous refrigerant into a high-pressure and high-temperature gaseous state. The heat converted by the compressor’s compression function is Q1. The high-temperature and high-pressure gaseous refrigerant exchanges heat with water, and the high-pressure refrigerant is cooled and condensed into a liquid state at room temperature. . During this process, the refrigerant releases heat to heat the water, making the water warm and turn into hot water. The heat absorbed by the water is Q3, the high-pressure liquid refrigerant is decompressed through the expansion valve, the pressure drops, and returns to a lower temperature than the outside world, which has the ability to absorb heat and evaporate. The low-temperature and low-pressure liquid refrigerant passes through the evaporator (air heat exchanger) to absorb the heat in the air and evaporates itself, changing from liquid to gas, and the heat absorbed by the refrigerant from the air is Q2. The refrigerant that has absorbed the heat becomes a low-temperature and low-pressure gas, which is then inhaled by the compressor for compression. This reciprocating cycle continuously absorbs heat from the air, and releases heat in the water-side heat exchanger to produce hot water. This cycle process is completed by the air energy heat pump (host) unit. As a high-efficiency heat collection and heat transfer system device, the air energy heat pump can convert the power consumed by the compressor into five times the heat energy (that is, the principle of Q1+Q2=Q3).

  • The working process of the air source heat pump: the state before entering the evaporator to absorb heat: liquid at low temperature and low pressure → absorb heat in the air through the evaporator (gasification) → the refrigerant becomes a gas at low temperature and low pressure → compressed by the compressor → becomes a high temperature High pressure gas→exchange heat with water through heat exchanger→turn into low temperature and high pressure liquid→throttle through throttling device→turn into low temperature and low pressure liquid→enter the evaporator to repeat the process.


Heat Pump Water Heater Workflow

  • 1. The compressor compresses the returning low-pressure refrigerant and turns it into high-temperature and high-pressure gas and discharges it.
  • 2. The high-temperature and high-pressure refrigerant gas flows through the copper pipe wrapped around the outside of the water tank, and the heat is conducted into the water tank through the copper pipe. The cooled refrigerant becomes liquid under the continuous action of pressure, and enters the evaporator after passing through the expansion valve.
  • 3. Due to the sudden drop in the pressure of the evaporator, the liquid refrigerant quickly evaporates into a gaseous state and absorbs a large amount of heat.
  • 4. At the same time, under the action of the fan, a large amount of air flows through the outer surface of the evaporator, the energy in the air is absorbed by the evaporator, the air temperature drops rapidly, and it becomes cold air and released.
  • 5. Then the refrigerant that has absorbed a certain amount of energy is returned to the compressor and enters the next cycle.


Brief introduction of four components of air source heat pump


  • A compressor (also called a "vapor pump" by some) is a driven fluid-mechanical device that elevates low-pressure gas to high-pressure gas, and is the heart of a heating system. It inhales low-temperature and low-pressure refrigerant gas from the suction pipe, drives the piston to compress it through the operation of the motor, and discharges the high-temperature and high-pressure refrigerant gas to the exhaust pipe to provide power for the heating cycle, thereby realizing compression→condensation (discharge) Heating cycle of heating)→expansion→evaporation (endothermic).


  • The condenser is a part of the heating system and belongs to a type of heat exchanger. It can convert gas or vapor into liquid, and heat the water in a very fast way with the heat in the tube. The gas is passed through a long tube (usually coiled into a solenoid) to dissipate heat into the surrounding water. Metals such as copper conduct heat well and are often used to transport steam. In order to improve the efficiency of the condenser, heat sinks with excellent thermal conductivity are often attached to the pipes to increase the heat dissipation area to accelerate heat dissipation. The working process of the condenser is an exothermic process, so the temperature of the condenser is relatively high.


  • The evaporator is a very important part of the four major heating elements. After compression and liquefaction, the low-temperature refrigerant passes through the evaporator and exchanges heat with the outside air. achieve the purpose of absorbing energy in the air.

Expansion valve

  • The expansion valve (throttle valve) is a device that controls the flow of refrigerant by changing the throttling section or throttling length in the heating system. It is generally installed between the evaporator and the liquid storage cylinder. The expansion valve (throttle valve) makes the liquid refrigerant of medium temperature and high pressure through its throttling to become wet vapor of low temperature and low pressure, and then the refrigerant absorbs the heat in the outside air in the evaporator. The expansion valve (throttle valve) controls the valve flow through the change of the superheat at the end of the evaporator to prevent the underutilization of the evaporator area and the occurrence of cylinder knocking.


Heat Pump System Terminology

  • HSPF: The Heating Seasonal Performance Factor is a measure of the heating efficiency of a heat pump. The higher the HSPF number, the more efficiently the heat pump can heat your home.
  • SEER: SEER (Seasonal Energy Efficiency Ratio) is a measure of the efficiency of air conditioning and heat pump cooling processes. The higher the SEER rating, the higher the efficiency and therefore the better the energy savings.
  • Refrigerant: R-410a (also known as Puron) is an environmentally friendly refrigerant designed not to damage the Earth's ozone layer. Federal law requires all manufacturers to phase out R-22, commonly known as Freon, and other ozone-depleting refrigerants over the next few years. R-410a refrigerant is approved by the U.S. Environmental Protection Agency as a replacement for R-22.
  • Standard Blower: A standard blower provides a specified amount of airflow based on the faucet setting.
  • Variable Speed ​​Blower: A high-efficiency blower designed to provide varying amounts of air flow depending on the desired result. These blowers improve the efficiency of humidification, dehumidification, air filtration and air balancing.
  • Humidification: This is the process of adding moisture to the air using a whole-house humidifier. During the winter months, heated air can make your house too dry. Adding moisture can protect your furniture and reduce static electricity. Connecting a humidifier to a variable speed blower allows you to control the humidity to the exact level you want.
  • Dehumidification Mode: The process of changing air flow and compressor operation can allow certain air conditioning applications to manage accurate indoor humidity levels.
  • Electric thermal staging: the ability to provide electrical backup heat in stages rather than all at once.





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