American Water Heater PowerVent Use & Care Manual page 30

Sequence of Operation...
1. During initial start-up or a call for heat, the
control will verify the vacuum switch is open.
2. Once the control verifies the blower vacuum
switch is open, the control will energize the
blower motor for the pre-purge sequence
(approximately 5 seconds).
3. The control will verify the blower vacuum
switch has closed, ensuring that the blower is
functioning properly and that the venting system
is not blocked.
4. The control will then proceed through a sequence
of self-diagnostics before initiating a trial for
ignition.
5. During the trial for ignition, the pilot will spark
in an attempt to light the pilot. Once the pilot
flame is established, the main gas valve will open
allowing gas to flow to the main burner.
6. The main burner and pilot will remain lit
throughout the heat cycle until the water
temperature setting is reached.
7. Once the water temperature setting is reached,
the control will close the main gas valve and
pilot valve which will extinguish both the main
burner and pilot burner flames.
8. The blower motor will stay energized for an
additional 30 seconds after the control verifies
that the burner flame is extinguished in order to
clear combustion gases from the water heater.
9. After the post-purge sequence, the control will
de-energize the blower motor and go into a stand-
by mode awaiting the next call for heat.
30
This water heater is equipped with a flammable
vapor sensor that is monitored continuously by the
electronic control in all modes of operation.
In the event that flammable vapors are detected, the
control will automatically shut down the water heater
and prevent the water heater from being started
again.
The following is a list of materials that will cause
the Flammable Vapor Sensor to shut down the water
heater.
Vapors of Gasoline.

Vapors of certain flammable paints, stains, and

thinners.
Vapors of vent pipe Cement & Solvents.

Bleach (direct contact with flammable vapor

sensor).
Some other flammable materials and their vapors.

If the flammable vapor sensor shuts down the water
heater, then the electronic control will display the
appropriate error code and you should then promptly
contact a qualified service technician.
Refer to the "WARNING" on page 3 for additional
information.