CHS-SVN011C-EN
15
Three-Way Valve Operation
(F0) Units
TRS low-temp air-handling units have an Apollo (F0) or
Belimo (F1) three way actuating valve which in standard
operation conditions is in a normally closed position.
However, when there is frost present in the coil and after
the heater contactor is turned on, the actuator is then
energized placing the valve in a normally open position
diverting the flow of fluid around the coils thus starting the
defrost cycle which duration is dictated by the thermostat
placed inside the control panel. Actuating valve should be
properly factory calibrated, however if this is not the case
please contact TRS for more information and before any
type of work is performed.
Please follow the procedure below to
manually adjust these electric actuators
•
The top switch and cam, control the closed position of
the valve.
•
The bottom switch and cam, control the open position
of the valve.
•
The actuator can be rotated without power by pressing
down on the override shaft connected to the actuator’s
gear box and rotating the shaft by hand.
•
Adjust the closed position by setting the top switch
first. Rotate the override shaft until the actuator is
closed. Adjust the upper cam until the flat of the cam
is resting on the lever of the limit switch as shown
below. Rotate the cam counterclockwise until the
switch clicks (corresponding to activation of the
switch), then rotate the cam clockwise until the switch
clicks again. Hold this position and tighten the set
screw on the cam.
•
Adjust the open position by setting the bottom switch.
Rotate the override shaft until the actuator is open.
Adjust the lower cam until the flat of the cam is resting
on the lever of the limit switch as shown below. Rotate
the cam clockwise until the switch clicks
(corresponding to activation of the switch), then rotate
the cam counter-clockwise until the switch clicks
again. Hold this position and tighten the set screw on
the cam.
