American Water Heater 160X3P Manual page 23

appear if there are combustion
air and/or exhaust vent issues
during the pre-purge sequence.
•
Code 991: This error code will
appear if there are combustion
air and/or exhaust vent issues
during heater operation.
WARNING! Familiarize yourself with
the components before attempting
these procedures. Use the Installation
Manual and reference the component
schematic on the last few pages of the
manual.
Safety first! These procedures must
be performed by licensed, qualified
service professionals only. Failure to
observe this warning could lead to
personal injury or death.
The manufacturer is not liable for
the actions of the technician if he/
she fails to adhere to any or all safety
procedures, specifically in regards to
electrical and gas safety.
1. Check the rating plate to verify that
the gas type of the water heater
matches the gas type applied to the
unit. NOTE: This water heater's gas
type is field convertible, confirm the
orifice installed matches the gas type
supplied. See Removing, Replacing,
and Verifying the Gas Orifice
Assembly on page 47. Next, make
sure that the gas-type DIP switch
setting is correct. (See Table 5 on
page 27.)
2. Verify that the venting meets the
requirements specified in the
installation manual (e.g., vent
diameter and length).
3. Verify the DIP switch settings.
3.1 Are the DIP switches set for
the correct vent size and
length? Refer to DIP Switch
Se ngs, p. 25 for the correct
se ngs. Each 90-degree
elbow is equal to 5 feet of
straight pipe. Refer to the
installa on manual for vent
requirements.
3.2 Is the heater set to the
correct eleva on? The
default se ng for your water
heater is 2,000 . above
sea level or less. A DIP
switch change is required for
installa ons that are higher
than 2,000 feet above sea
level. Refer to "DIP Switch
Se ngs" on page 26.
4. Check for wiring connections for
any breakage and/or burn marks on
the PCB.
5. Check for obstructions in the vent
or intake air lines. Clear them if any
are found. Check the following:
•
Air intake and exhaust
•
Rain protection tray screen
•
Fan motor intake
6. Verify that the terminations meet
the minimum clearances that
are outlined in the installation
manual and local codes. (Doing so
will minimize the risk of flue gas
recirculation.) Also, ensure that no
other appliance's exhaust gasses
can be pulled into the intake.
7. Check for signs of contaminated air
inside the water heater's cabinet
and inside the fan on the fan
blades. Clean the fan and cabinet
if any debris is present. It may also
be necessary to inspect for debris
or a partial blockage of the burners
that could affect the flame quality.
.
On-Demand Water Heater Service Handbook for X3P Models
INCREASE
DECREASE
Figure 5: Checking Combustion Status.
8. Check the following:
8.1 Is the gas supply pressure
within specifi ed limits when
the heater is in standby
and when it is running with
mul ple taps open and MAX
pressed on the computer
board?
8.2 If the pressure diff erence
between standby and
maximum fi ring is greater
than 1 inch W.C., the supply
line, gas meter, and/or
regulator may be undersized.
NOTE: In Canada, do not
exceed the maximum
allowable pressure drop
permi ed by B149.1.
8.3 Verify that the gas lines
are sized for the correct
volume of gas. NOTE: Gas
line capacity will vary based
on type of gas line material
used. Refer to the installa on
manual or the current
edi on of the Na onal Fuel
Gas Code, ANSI Z223.1/
NFPA 54 (U.S.) or Natural Gas
and Propane Code, B149.1
(Canada).
NOTE: Do not proceed to the
next step until this one has
been completed and these
causes have been ruled out.
Improperly installed venting,
incorrect DIP switch settings,
MAX
MIN
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