AERCO SWDW68 U-Tube Double-Wall Heaters w/ECS - Manual (Page 73)

HE-
111 − CORRECTIVE MAINTENANCE
Rev B Mar 2013
8-19
assembly of the heat exchanger.
c. Figure 2-1. Disconnect the solenoid cable (terminated in a 3-pin DIN connector) from the
Over-temperature Solenoid Valve on the upper head assembly of the heat exchanger.
d. Disconnect the mixed temperature cable (terminated in a 2-pin Molex connector) from the
mixed temperature sensor mounted at the Cold Water Input to the heat exchanger.
5. After the Control Box cables have been disconnected, remove the two hex nuts securing the Control
Box top and bottom mounting attachments to the heat exchanger. Completely remove the Control
Box from the heat exchanger.
6. To replace the Control Box, reverse Steps 1 through 5.
8.3.2 Replacing the Temperature Controller
The Temperature Controller is located on the recessed panel behind the Control Box door, as shown in
Figure 8-8. Remove and replace the Temperature Controller as follows:
1. Open the Control Box door to access the Temperature Controller.
2. The Temperature Controller is installed in a sleeve as shown in Figure 8-10. To unplug and remove
the Temperature Controller from its sleeve, pry the latching ears outward and pull the Temperature
Controller out of the panel.
3. To install a replacement Temperature Controller, slide it into the front panel sleeve until the latching
ears click into place. When the new Temperature Controller is in place, adjust the setpoint to the
required temperature using the adjustment procedures in 4.3.1.
Figure 8-10. Temperature Controller Installation
4. Close and secure Control Box front door.
8.3.3 Replacing the Over-temperature Switch
The Over-temperature Switch performs a switching function and generates an alarm when the preset
temperature limit is exceeded. Remove and replace the Over-temperature Switch as follows:
1. Open the Control Box door and locate the Over-temperature Switch (Figure 8-11a).
2. Loosen the captive screw on upper part of recessed panel behind the door and open the swing-down
panel to access the terminal wiring connections and retaining clips of the Over-temperature Switch
assembly.