Preventative Maintenance; Pneumatic Control Troubleshooting - Carrier 35E Installation And Start-Up Instructions Manual

DA HEATING*
Reset
MAX
Span
LO STAT ΔP
F
L
O
W
HI STAT ΔP
MIN
0 3 8 13 psig
Δ
Reset Start*
ROOM TEMPERATURE
RA HEATING
Reset
MAX
Span
HI STAT ΔP
F
L
O
W
LO STAT ΔP
MIN
13 8 3 0 psig
Δ
Reset Start
ROOM TEMPERATURE
*May require changing the RESET START from 8.0 to 3.0 psig if
sequencing is involved.
Fig. 12 — Reset Cycle for CSC-3011 Control
NOTE: IF the LO STAT ΔP Limit must be set at "0" (zero min-
imum), do not turn the LO STAT ΔP knob fully clockwise. The
knob will adjust one and one-half turns after a zero minimum is
reached. Turning the LO STAT ΔP knob fully clockwise will
result in a negative reset condition. This means that when the
controller begins to reset at the reset start point, it must first
overcome the negative adjustment and will not begin to reset
from "0" until a higher thermostat reset pressure is reached.
This negative reset will also reduce the effective range of the
controller by reducing the low end reset, narrowing the reset
span. If a zero minimum is required, adjust the LO STAT ΔP
knob until the controller just begins to crack the damper open,
and then back-off one-quarter turn and verify zero airflow.
Controller does not reset to maximum or minimum set point during
balance procedure.
Controller does not reset to maximum or minimum set point during
operation.
Pneumatic actuator does not stroke fully.
Air valve stays in wide open position.
NOTE: Always Check:
1. Main air pressure (15 psi to 25 psi) at the controller.
2. Disconnected or kinked pneumatic lines to the controller.
3. Quality of compressed air (oil or water in lines).
DA COOLING
Reset
MAX
Span
F
LO STAT ΔP
L
O
W
HI STAT ΔP
MIN
0 3 8 13 psig
Δ
Reset Start
ROOM TEMPERATURE
RA COOLING*
Reset
MAX
Span
LO STAT ΔP
F
L
O
W
HI STAT ΔP
MIN
8
13 3 0 psig
Δ
Reset Start*
ROOM TEMPERATURE
Table 7 — Troubleshooting
PROBLEM
(This is typically 2 /
1
2
the fully clockwise position.)
NOTE: After the "LO STAT P" and "HI STAT P" initial ad-
justments are made, cycle the thermostat pressure a few times
to settle the internal reset mechanisms and verify settings. Fine
tune the settings if necessary. The thermostat pressure may be
left at a high pressure and the "G" port cap may be removed
and replaced to cycle the reset mechanism.
RESET START setting is factory set at 8.0 psig. This is the
lowest thermostat pressure that the LO STAT P airflow will
begin to reset towards the HI STAT P airflow. To change the
RESET START setting: regulate thermostat pressure to the "T"
port to the desired reset start point pressure, adjust RESET
START adjustment until pressure at the "G" port is slightly
higher than 0 psig, i.e., 0.1 psig.
NOTE: The "G" port taps into the controller's internal reset
chamber, which always starts at 0 psig. The RESET START
adjustment is a positive bias adjustment that sets the desired
thermostat start point to the controller's internal reset start point
of 0 psig.
RESET SPAN setting is factory set at 5.0 psig. This is the re-
quired change in thermostat pressure that the controller will re-
set between the LO STAT P setting and the HI STAT P set-
ting. To change the RESET SPAN setting: adjust RESET
SPAN adjustment until pressure at the "G" port equals the de-
sired reset span pressure. (Do not adjust.)
NOTE: The "G" port taps into the controller's internal reset
chamber, which will always be at a pressure between 0 psig
and the RESET SPAN pressure.

Preventative Maintenance

1. Inspect pneumatic tubing for loose connections or leaks.
2. Clean out pneumatic line filters regularly according to
manufacturers recommendations.
Pneumatic Control Troubleshooting —
Table 7.
PROBABLE CAUSE
Balancer is using the thermostat for control signal. An artificial signal
must be provided in place of the thermostat.
Thermostat is not demanding maximum or minimum air volume. Main
air pressure at the controller is less than 15 psi.
Leak in pneumatic line between the controller and the actuator. Main
air pressure at the controller is less than 15 psi. Leak in the diaphragm.
Velocity probe is blocked by an obstruction (sandwich bag, etc.).
Insufficient supply air in the inlet duct.
4. Proper thermostat signal and logic (Direct/Reverse Acting).
5. Blocked velocity probe or insufficient primary supply air.
6. Leaks in the actuator diaphragm.
7. Mechanical linkage of the actuator/air valve.
12
knob rotations counter clockwise from
See