AERCO SWDW68 U-Tube Double-Wall Heaters w/ECS - Manual (Page 40)

HE-
111 − SCHEDULED MAINTENANCE
Rev B Mar 2013 6-2
6.4 QUARTERLY MAINTENANCE
6.4.1 First Three Months
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Accumulated Shell Solids
After the first three months of initial operation, drain the heat exchanger as follows:
1. Close all stop valves in the Steam Input and Condensate Output lines.
2. IN THIS ORDER, close the stop valves in the:
a. Hot Water Output line
b. Recirculation line
c. Cold Water Input line
3. CAREFULLY open the relief valve in the upper head assembly to relieve pressure in the shell. If fluid
continues to flow from the relief valve, one of the Cold Water Input stop valves is either leaking or is
not completely shut off. Securely close all Cold Water Input stop valves until there is no more flow
from the relief valve.
4. WITH THE RELIEF VALVE HELD OPEN (to prevent creating a vacuum in the shell), open the
plugged drain at the bottom of the shell (see Figure 3-3), and drain the heat exchanger completely.
5. Examine the water being drained.
a. If the amount of solids in the water being drained appears to be heavy, set a schedule to drain
the heat exchanger every 3 months.
b. If the amount of solids appears to be light, set a schedule to drain the heat exchanger every 6
months.
c. Even if the amount of solids appears to be very light or not at all, set a schedule to drain the heat
exchanger at least once each year.
6. To refill the heat exchanger and place it back into operation, replace the drain plug and perform the
Pre-Operational and Operational steps listed in Chapter 5.
6.4.2 Each Quarter
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Valve Calibration
Refer to 4.2 and perform the CXT-E Actuator adjustment procedure as instructed.
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Over-temperature Switch
Check the operation of the Over-temperature Switch as follows:
1. Refer to 4.3.2 and lower the over-temperature setting to approximately 5°F below the present
setpoint, as shown in the lower display of the Temperature Controller.
2. Verify that an over-temperature alarm is generated and the following events occur:
a. The CXT-E Control Valve closes.
b. The Over-temperature Solenoid (located at top of heat exchanger) opens and expels water from
the system.
c. The Over-temperature Switch generates an audible alarm.
3. When you have successfully completed the over-temperature alarm check, return the Over-
temperature Switch to its original setting.