Table 14-1(A).Determining Superheat
Obtain the temperature of the suction line at the point where the TEV sensing
bulb is attached.
a. Take the temperature reading with a dial thermometer similar to the one
shown in figure 14-20(E), or use some other temperature measuring device that
senses surface temperatures accurately.
Obtain the suction pressure inside the piping at the location of the remote sensing
a. If the valve is externally equalized, you can place a gauge in the external
equalizer line. This is the most accurate method.
b. The alternate method is to read the manifold pressure gauges at the
compressor and add the estimated pressure drop through the suction line between
the bulb and compressor. The sum of the two pressures provides approximate
pressure at the location of the remote bulb.
Convert the pressure you received in step 2 into saturated evaporator pressure.
a. Use a pressure temperature chart. When using the chart, ensure that you are
looking at the proper refrigerant.
Simply subtract the temperature in step 3 from the temperature in step 1. This is
Note: When adjusting the expansion valve, turn the adjusting stem no more than one full
turn and wait approximately 15-30 minutes for the system to balance out. Once the system
is balanced, recheck the superheat setting by following the steps in table 14-1(A).
RECEIVERS AND ACCUMULATORS
work on the unit. Additionally, when a unit
is equipped with a receiver, the quantity of
The receiver is a storage tank for liquid
refrigerant in the system is less critical than a
refrigerant. When a refrigeration system is
unit not so equipped. Figure 14-23 shows the
equipped with a receiver, you can close the
location of a receiver installed in a system.
outlet valve (king valve) and pump refrigerant
T h i s i s a c o m m e r c i a l s y s t e m w i t h an
into the receiver. This enables you to store
a i r - c o o l e d c o n d e n s e r , a t h e r m o s t a t ic
the refrigerant while you
expansion valve, and a V type of reciprocating