How Does a Heat Pump Work

How Does a Heat Pump Work

Components in a heat pump

Refrigerant:

A refrigerant is a fluid that easily boils from a liquid into a vapour and back to a liquid at certain pressures. Refrigerants used in air conditioning and heat pumps boil at really low temperatures and therefore can absorb heat and release it from outside in or inside out. Refrigerants are well known for the harmful effects on the ozone layer and the negative impact they have on global warming. Refrigerants are being designed to be less harmful to global warming and to further protect the environment It is also illegal to knowingly release refrigerants into the atmosphere. Heat pump installers must hold an approval handler certificate and any refrigerants left in old or broken heat pumps must "recovered" before dismantling.

Reversing Valve:

This is a critical piece of equipment in a heat pump as it allows a heat pump to change from heat mode to cool mode. It can achieve this by being able to control the direction the refrigerant flows in. Without a reversing valve you would only have an air conditioner where it could only cool a room.

Filter drier:

This filter is added to the liquid line of a heat pump and is essential to keep the contaminants such as moisture, acids, wax, and other contaminants out of the system. Having contaminants circulating around a heat pump can cause premature heat pump break down and reduce heat pump efficiency. Moisture that can condense on the inside of the heat pump pipes need to be removed from the line as the moisture can react with the refrigerant and create an acid by-product. Over time, the acid can burn the insulation off the wires in the compressor and cause it short circuit and cease functioning.

Sight Glass:

a sight glass allows a technician to see inside the liquid line of a refrigerant and serves two purposes. One to see that the amount of moisture in the liquid line is within an acceptable range and TWO to check that the refrigerant is in a liquid state before entering the expansion valve

Expansion valve:


The refrigerant inside a heat pump is kept at two very different pressure levels. There is a high pressure line (that is called the liquid line) and the low pressure line that is the vapour line. The Function of an expansion valve is to limit how much refrigerant can pass thereby creating a high pressure in the line behind it and a low pressure in the line infront of it. When the refrigerant passes the expansion valve from high pressure to low pressure the refrigerant rapidly cools down into a cold gas due to the pressure change. It is then able to absorb more heat to cycle back around and repeat the process.

 

Heat mode

     

  1. The refrigerant leaves the compressor as a super-heated vapour and is forced towards the reversing valve
  2. The reversing valve is configured to heat mode where it diverts the refrigerant towards the indoor unit
  3. The refrigerant flows through the indoor unit where it releases the stored heat into the surrounding air and a blower fan distributes the heat
  4. The refrigerant cools and condenses back into a liquid under high pressure and continues down the pathway towards the outdoor unit
  5. The refrigerant flows through the correct direction of the first “Non-Return Valve” (otherwise known as a one-way valve) and bypasses the first expansion valve
  6. The refrigerant flows through a filter drier that functions to adsorb moisture and provide physical filtration for other contaminants and then passes through a sight glass that enables a technician to inspect the moisture content and quality of the refrigerant.
  7. The refrigerant is blocked by a second “Non-Return Valve” but completes the pathway through a second expansion valve where it is released as a super-cooled liquid on the other side.
  8. The liquid refrigerant enters the outdoor unit under low pressure
  9. The refrigerant absorbs heat from the atmosphere, boils and travels towards the reversing valve
  10. The reversing valve then diverts the refrigerant back to the compressor to repeat the process

     

 

Cool mode

      Heat pump cool mode

  1. Refrigerant leaves the compressor as a super-heated vapour and is forced towards the reversing valve
  2. The reversing valve is configured to cool mode where it diverts the refrigerant towards the indoor unit
  3. The refrigerant flows through the outdoor unit where it releases the stored heat into the surrounding air
  4. The refrigerant cools and condenses into a liquid under high pressure and continues down the pathway towards the indoor unit
  5. The refrigerant flows through the correct direction of the first “Non-Return Valve” (otherwise known as a one-way valve) and bypasses the first expansion valve
  6. The refrigerant flows through a sight glass that enables a technician to inspect the moisture content and quality of the refrigerant and then passes through a filter drier that functions to adsorb moisture and provide physical filtration for other contaminants
  7. The refrigerant is blocked by a second “Non-Return Valve” but completes the pathway through a second expansion valve where it is released as a super-cooled liquid on the other side.
  8. The liquid refrigerant enters the indoor unit under low pressure
  9. The refrigerant absorbs or sucks up heat from the room the indoor unit is positioned, boils, and travels towards the reversing valve. As the heat is taken away, the air is cooled and is distributed by a blower fan
  10. The reversing valve then diverts the refrigerant back to the compressor to repeat the process

     

 

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