SiBE811001EB
Troubleshooting
CONVENI-PACK
320
9.1.3 Proper Method of Mounting Feeler Bulb
1. Feeler bulb mounting position to the circumferential direction of suction pipe
An approximate reference position is indicated by the segment of pipe diameters as a
position in which the feeler bulb senses proper temperatures of the refrigerant vapor without
having influence of the flow of refrigerant and refrigerant oil in the suction pipe.
The liquid refrigerant is heavier than vapor and flows in the lower part of the pipe. Therefore,
to avoid that, the positions shown in figures above are recommended.
If the feeler bulb is mounted in the vertical position of the suction pipe, it will not be clear
through what part of the pipe the liquid refrigerant flows, thus disabling the feeler bulb to
sense accurate temperatures.
2. Shape of suction pipe and mounting position of feeler bulb
45º
Feeler bulb
Suction pipe diameter
of
φ
22.2 mm or less
Suction pipe diameter
of
φ
25.4 mm or more
Feeler
bulb
Feeler bulb
Suction pipe
If no appropriate
horizontal pipes are
available, place the
feeler bulb with the
front end downward
and the capillary
connection port
upward.
Improper shape of suction pipe
Evaporator
Showing feeler bulb mounted to trap part
The feeler bulb is mounted to the
trap part in the suction pipe.
In this case, the liquid refrigerant
and refrigerant oil dwells in the
trap part, thus disabling the
feeler bulb to sense accurate
temperatures to cause improper
operation of the expansion
valve.
Furthermore, if the liquid
refrigerant in the trap part
moves, periodic changes in
temperature will occur to cause
hunting of the suction pressure.
Thermostatic
expansion
valve
Feeler
bulb
