A.O. Smith 12 40GPC T 100 - Manual (Page 28)

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PRESSURE SWITCH REMOVAL / REPLACEMENT
Important: Use only factory authorized replacement
parts. If you lack the necessary skills to properly
perform the installation, you should not proceed, but
get help from a qualified service technician.
Tools required: Phillips Head Screwdriver.
Removing the Pressure Switch:
1. Set the gas control valve/thermostat to its lowest
setting by pressing the “COOLER” and “HOTTER”
buttons together at the same time holding for 1
second. Then press the “COOLER” button to the
lowest setting (Figure 36).
2. Turn gas control switch to the “OFF” position
(located right side of the gas control valve/
thermostat) and turn off the gas supply to the unit
(Figure 37).
3. Disconnect the electric connection by unplugging
the transformer from the wall outlet (Figure 37).
4. Remove the manifold cover/ outer door from the
unit by depressing on the lower portion and pulling
outward.
5. Remove the air pressure tubing from the air
pressure switch by pulling downward on the
tubing at the connection to the air pressure switch
(Figure 38).
6. Remove the two (2) electrical flag terminals from
the switch by pulling outward and off of the switch
(Figure 39).
7. Using a phillips head screwdriver, remove the 2
screws securing the pressure switch to the water
heater’s side (keep these screws in a safe place
for reinstallation later) (Figure 39).
Installing the Pressure Switch:
8. Secure the new pressure switch to the water
heater’s side by reusing the 2 screws removed in
step 7 (Figure 39).
9. Reattach the two (2) electrical flag terminals
by pushing the flag terminals onto the switch
(Figure 39).
10. Reattach the air pressure tubing to the air
pressure switch by pushing the tubing onto the
connector until the end of the tubing pushes to the
shoulder of the connector (Figure 38).
11. Turn on the electrical and the gas supplies to the
water heater. Plug in the electric connection from
the transformer to the electric outlet (Figure 37).
12. Restart the water heater by following the
directions on the “Lighting and Operating
Instructions” label located on the front of the water
heater.
13. Upon verifying proper operation of the water
heater, replace the manifold cover/outer door.
Figure 39.
SCREW
AIR PRESSURE
TUBING
FLAG
TERMINALS
PRESSURE
SWITCH
g
COOLER HOTTER
Electronic Control Display
Figure 36.
PRESSURE SWITCH
TUBING CONNECTION
Figure 38.
ON/OFF
SWITCH
ON
OFF
Figure 37.
UNPLUGGED