324 Electrical Power Systems Technology
placed in the cooling-cycle position. In some systems this is accomplished
by a manual changeover switch, whereas in others it is achieved automati-
cally, according to the thermostat setting. The operating position of the
valve simply directs the flow path of the refrigerant.
When the cooling cycle is placed in operation, it first causes the re-
frigerant to flow from the compressor into the indoor coil. During this part
of the cycle the refrigerant Is in a low-pressure gaseous state and is quite
cool. As the circulation process continues, the indoor coil begins to absorb
heat from the inside air of the building. Air passing over the indoor coil
is cooled and circulated into the duct network for distribution throughout
the building.
After leaving the indoor coil, the refrigerant must pass through the
reversing valve and into the compressor. The compressor is responsible
for increasing the pressure of the refrigerant and circulating it into the
outdoor coil. At this point of the cycle, the refrigerant gives up its heat to
Figure 12-9. Heating cycle operation