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9AQ4 Manual
3 Operation
3.1 First time start up
3.1.1 Time delay relay
1. The AQ4 power vent kit is equipped with a time
delay relay. It is supplied with the time delay set
at the (0.1) second position
2. If installing the AQ4 with standing pilot models
1600P or 425PN, no adjustment is required.
3. If installing the AQ4 with hydro ignition models
1600H or 425HN, move the adjuster on the time
delay to the (2) second position. (Fig. 11B)
4. To access the time delay relay, unplug powervent
and remove the electrical box cover on power vent
motor. (Fig. 11A)
Fig. 11 Accessing the time delay relay
cover
screw
cover
screw
Fig. 11B Time delay relay positioning
3.1.2 Verifying proper operation of powervent
It is important to verify proper operation of the power
vent motor before commissioning the system:
1. Slowly turn on cold water supply and check for any
leaks at newly installed ow switch and piping.
2. Plug power vent motor into 120VAC outlet.
3. With the gas supply to the water heater turned
off (see water heater manual) turn on a hot water
tap. The power vent motor should come on. Verify
the back-draft apper is open and air is being
blown out of the power vent hood. If not, see the
troubleshooting tips in Chapter 5.
4. Turn off hot water tap.
Note: The AQ4 power vent fan motor is equipped
with a 45 second post purge cycle. The fan motor
should continue to run for this length of time after
the hot water ow has been shut off.
5. Open gas supply to the water heater and follow the
lighting instructions in water heater installation
manual.
3.1.2 Draft test
1. Operate the water heater by running hot water.
Check for proper combustion and ensure there
is no spillage by holding an recently extinguished
Operation
match or other visible smoke source in front of the
draft divertor. The smoke from the extinguished
match should be quickly sucked into the opening
and up the exhaust venting. If the smoke is blown
back, there is a blockage in the vent or the vent
motor is not operating properly.
3.1.3 Safety interlock test
1. Open the gas supply to the water heater.
2. Block the back draft apper from opening from
the outside.
CAUTION: The metal of the back draft
apper will be hot when conducting this
test.
3. Turn on the hot water supply to allow the burner
to activate. Hot ue gasses will spill from the
draft diverter momentarily. In less than three (3)
minutes, the linear spillage switch should trip,
opening the the heater safety circuit and halting
the ow of gas to the heater.
NOTE: If spillage switch does not shut off the
gas, check that you have made the proper safety
circuit connections. If the switch still does not
trip, contact Bosch Water Heating.
4. After the burners shut off, turn off hot water
supply and wait 2-3 minutes...then push the reset
button on the linear spillage switch.
5. Depending on model, light the pilot or run hot
water and repeat Safety Interlock Test,
(Step 1-4)
6. Ensure back draft apper moves freely and closes
properly once test is complete.