AERCO SWDW68 U-Tube Double-Wall Heaters w/ECS - Manual (Page 49)

HE-
111 − TROUBLESHOOTING
Rev B Mar 2013 7-7
Table 7-2 TROUBLESHOOTING – ELECTRONIC CONTROL VALVE CXT-E
NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION
T10 System not operating.
Control Valve is closed and
Hot Water Output water
temperature is far below
setpoint.
CAUTION
Over-tightening the
packing nut may trap the
Valve stem and slow or
stop Valve motion.
1. Power is not being supplied to the
Control Valve.
2. The Actuator has failed.
3. Control signal is not being
supplied from the Temperature
Controller.
4. The Actuator linkage has failed.
1. Disconnect Actuator plug and verify that 24 VDC power is present at
pin 2 of the Actuator cable. Restore power as necessary. Proceed to
Table 7-3, Item T17, and verify that the Over-temperature Switch is
not tripped.
2. Replace Actuator.
3. Verify presence of 4 – 20 mA control signal at pin 3 of the Actuator
cable. If the control signal is not present, troubleshoot ECS per
Table 7-3.
4. Check Actuator linkage and verify that it is properly connected and
that the pin in the linkage is in the correct position for the installed
Valve size
T11 System overheats by more
than 10°F above the
desired setpoint.
Outlet temperature is
below the over-
temperature limit setting.
CAUTION
Over-tightening the
packing nut may trap the
Valve stem and slow or
stop Valve motion.
1. Control Valve is not fully closed.
2. Actuator U-bolt loose.
3. The Actuator has failed.
4. Temperature Controller is not set
properly or is defective.
5. Actuator is not properly secured
to the linkage assembly.
6. Foreign matter in the Control
Valve seat
7. Recirculation pump failure.
1. Check the 4 – 20 mA control signal being supplied to the Actuator. If
the signal is greater than 4 mA when the heater outlet temperature is
10°F (or more) above the desired setpoint, proceed to next item ion
the list.
2. Check Actuator U-bolt securing it to the linkage assembly. Tighten as
needed (per 8.2.4, Step 55) and readjust the CXT-E Control Valve per
4.2.
3. Replace Actuator.
4. Refer to Chapter 4 Adjustments. Check the current setting of the
Temperature Controller. Readjust if necessary. If adjustment does not
clear the fault, proceed to Table 7-3, Item T16, and proceed as
instructed.
5. Check the Actuator U-bolt that secures the linkage assembly. Tighten
if needed and readjust the Control Valve per section 4.2.
6. If the Valve still does not close after checking the above items,
disassemble the Valve and clean the seat per 8.2.2, steps 18 –28.
7. Proceed as follows:
a. Check input power to the recirculation pump.
b. Check the temperature of the copper tube above the pump. It
should be the same as the outlet DHW temperature. If cold, repair
or replace the pump, as required.