AERCO SWDW68 U-Tube Double-Wall Heaters w/ECS - Manual (Page 50)

HE-
111 − TROUBLESHOOTING
Rev B Mar 2013 7-8
Table 7-2. TROUBLESHOOTING – ELECTRONIC CONTROL VALVE CXT-E, continued
NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION
T12 System outlet water
temperature is below
desired setpoint.
CAUTION
Do not over-tighten the
packing nut, as it may trap
the Valve stem and slow or
stop Valve motion.
1. Temperature Controller is not set
properly.
2. Control Valve is not opening
properly.
3. Steam pressure is too low
4. Trap in Condensate Output line is
malfunctioning.
1. Refer to 4.3.1 and check the current Temperature Controller setting.
If the setting is below the desired setpoint, readjust as necessary.
2. Proceed as follows:
a. Ensure that the Actuator is correctly secured to the Control Valve
linkage assembly. Tighten mounting bolts, as needed.
b. Verify that 24 VDC power and 4 - 20 mA control signal are
present at Actuator pins 2 and 3, respectively.
c. To ensure that the Valve is not binding, check the Valve shaft
seal retainer per 8.2.1, steps 1 through 10. Replace items as
necessary.
3. Check the high-side steam pressure to the Control Valve to ensure it
is correct.
a. If steam pressure is lower than the system design specification,
correct as necessary.
b. If the high-side steam pressure drops as the Control Valve
opens, the strainer may be clogged, or there may be a partially
closed valve in the upstream line. Correct as required.
4. Check for improper operation of the trap in the Condensate Output
line, as follows:
a. If the low-side pressure gauge shows pressure, but steam does
not heat properly, CAREFULLY break the Condensate Output line
connection AHEAD of the trap.
b. Allow condensate to run out into the floor drain.
c. If the heat exchanger outlet temperature rises to the desired
setpoint with the condensate connection open, repair or replace
the trap.