Table of Contents
Advertisement
How a Heat Pump Works
7
The heat pump essentially works in the same way as your refrigerator but in reverse. The Ecodan
is hermetically
®
sealed (no refrigeration piping involved) with R410A refrigerant, the cycle it completes to produce heat is known
as the vapour compression refrigeration cycle:
Step 1
The first phase begins with the refrigerant being cold and low pressure. The refrigerant within the circuit is
compressed as it passes through the compressor. It becomes a hot, highly pressurised gas. The temperature
also rises typically to 60°C.
Step 2
The refrigerant is then condensed as it passes across a plate heat exchanger. Having a cooler side to the heat
exchanger it decreases the temperature, so it changes the property of the refrigerant from a gas to a liquid.
Step 3
The refrigerant as a cold liquid still has a high pressure. For expansion to occur it passes through
an expansion valve. The pressure drops but it is still a cold liquid.
Step 4
The final stage of the cycle is when the refrigerant passes into the evaporator and evaporates. It is at this point
when some of the free heat energy in the outside air is absorbed by the refrigerant. It is only the refrigerant that is
being passed through this cycle; the water is heated up by the plate heat exchanger. The cooler water extracts
energy from the hotter refrigerant, i.e. the water is heated as it passes across the plate heat exchanger. This water
flows towards the heating system and hot water storage tank, where its energy is used to provide domestic hot
water and space heating.
Boiling points:
The refrigerant used within the cycle has a different boiling point to water, which boils (turns from liquid to gas) at
100°C. This is only true at atmospheric pressure. When the pressure increases so does the boiling temperature;
decrease the pressure and boiling temperature drops. Liquid turns to gas at a lower temperature. The boiling point
changes when the pressure changes. Refrigerants have different properties to water and have much lower boiling
temperatures. During the fourth stage of the cycle the outside ambient temperature even in winter is therefore hotter
than the temperature of the refrigerant and will heat it.
FTC4 Installation Manual
10
Advertisement
Table of Contents
