A.O. Smith 110 Series Instruction Manual page 38

TROUBLESHOOTING GUIDELINES
Please check guidelines below. For your safety, water heater service should be performed only by a qualified service technician.
# LED STATUS
B C D E F The self-diagnostic test determined resistance
15
of the black resistor wire on ignitor assembly
plug is not within tolerance.
Air pressure switch circuit is opening
B C D E F
16
repeatedly during one heating cycle. May be
caused by air pressure switch and/or the vent
temperature limit switch (these two switches
are wired together in a "series" circuit).
TROUBLE SHOOTING
Read the GENERAL SAFETY INFORMATION section first.
INTELLI-VENT TROUBLESHOOTING CHART - USER CONTROL
PROBLEM
1. Turn off power to the water heater.
2. Unplug the ignitor assembly plug from the control. Check
the resistance of the black resistor wire between pins
3 & 4 with an ohm meter. 2.1 If the reading taken is more
than 100,000 (50,000 for data code before 0616; 70,000
for data code 0617 through 0709) ohms replace the ignitor
assembly. 2.2 If the reading taken is less than 100,000
(50,000 for data code before 0616; 70,000 for data code
0617 through 0709) ohms replace Intelli-Vent™ control.
1. Ensure air pressure switch hose is not kinked or clogged;
ensure the blower housing is clear of any condensation.
2. Check vent temperature limit switch - if it is determined
that the vent temperature limit switch is opening its
contacts at normal operating temperatures during heating
cycle - replace the vent temperature limit switch.
3. Ensure water heater is not over-firing. 3.1 Check burner
orifice size and ensure the correct orifice is installed;
replace as necessary. 3.2 Check manifold gas pressure
and ensure it is within 0.3" W.C. (75 Pa) of listed rating on
Intelli-Vent™ control valve. Manifold gas pressure is
non-adjustable, if manifold gas pressure is off by more
than 0.3" W.C. (75 Pa), replace the Intelli-Vent™ control.
4. Ensure condensate lines are not obstructed. Check and
clear all condensate lines including the floor condensate
drain line.
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SOLUTION