User Guide

2
REMOTE BULB WELL
When it becomes desirable to increase the sensitivity of the
remote bulb to a change in the refrigerant gas temperature leaving
the evaporator, it may be necessary to use a remote bulb well. This is
particularly true for short-coupled installations with large suction lines
(2-1/8" OD or larger). Remote bulb wells should be used:
(1) when very low superheats are desired, and (2) where convected
heat from a warm room can inuence the remote bulb. (See Figure
4.)
RAPID RESPONSE BULB AND WELL
One of the problems encountered in the average refrigeration
system is the return of liquid refrigerant to the compressor (known
as ood-back). Proper application of the rapid response remote bulb
and matching well will minimize this problem. Due to reduced thermal
mass, the rapid response bulb and well respond to changes in suc-
tion gas superheat far more rapidly than the larger standard remote
bulbs applied either as a “strap-on” type or inserted in the standard
remote bulb well.
The rapid response bulb and well provide the extra quick closing
action necessary for positive protection against liquid ood-back as
well as the smooth control necessary for optimum system perfor-
mance. Figure 4 illustrates the proper method of installation. The
rapid response bulb may be used in either horizontal or vertical suc-
tion lines.
Since a denite remote bulb volume is required for any type of
charge other than gas, the rapid response bulb is available only with
the “G” (gas) charge. To designate the rapid response bulb, sufx the
charge symbol in the valve type or power assembly number with the
letter “S”, i.e. TCL1-FGS55 or X7726-FGS55 1A.
Do not under any circumstances locate either type of remote bulb
in a location where the suction line is trapped. (See Figure 1.) If the
liquid refrigerant collects at the point of the remote bulb location, the
thermal expansion valve operation will be erratic and possibly the
valve thought to be defective. Large uctuations in superheat in the
suction gas are usually the result of trapped liquid at the remote bulb
location. Even on properly designed suction lines, it is sometimes
necessary to move the remote bulb a few inches either way from
the original location to obtain best valve action. Always locate the
remote bulb on the evaporator side of the heat exchanger.
SUPERHEAT ADJUSTMENT
ZZ Thermal Expansion Valves are factory-set for a static superheat.
However, the superheat should be adjusted for the application.
Improper superheat adjustment may result in system malfunction.
To properly adjust the thermal expansion valve to other superheat
settings:
1. Remove seal cap on side of valve.
2. Turn the adjusting stem in a clockwise direction to increase the
superheat, and counterclockwise to decrease superheat (approxi-
mately 1/2°F per turn, R22 applications).
Note: Allow adequate time between adjustments for system to stabi-
lize before checking superheat.
3. When the desired superheat setting is achieved, reinstall the seal
cap.
SERVICE INSTRUCTIONS
WARNING: Before opening any system, make sure the pressure in
the system is brought to and remains at atmospheric pressure. Fail-
ure to comply may result in system damage and/or personal injury.
To inspect, clean, or replace parts of the thermal expansion valve:
1. Disconnect equalizer line.
2. Remove the cap screws.
3. Carefully lift off the power assembly.
4. Remove cage assembly and gaskets.
5. Lightly oil gasket with refrigeration oil.
NOTE: Good service practice requires replacing all gaskets when-
ever a valve is opened.
6. Assemble in the same order as disassembled.
7. When putting the power assembly on, make sure the cage as-
sembly lugs line up with the slots inside the power assembly (see
gure 2).
8. Tighten cap screws evenly and torque to 300±25 inch pounds.
NOTE: For proper sealing of all gasket surfaces, the torque must
be applied evenly. The following recommended procedure must be
followed:
1) Tighten both cap screws nger tight.
2) Alternately tighten each cap screw at 50 in-lb increments until
the 300 in-lb spec is obtained on each.
IMPORTANT: Failure to follow these instructions can result in a
valve that has excessive internal leakage, leading to "ooding", if
a new valve oods on initial start-up, it is recommended that all
gaskets be replaced and the valve be re-installed carefully
following the proper torque instruction noted above.
NOTE: Over-torquing may result in body damage.
9. Check for leaks.
Figure 4
TEV REMOTE
BULB TUBING
BULB
WELL
SUCTION