Blocked Exhaust; Blower Prover Failure - A.O. Smith BTX 100 Service Handbook

fault messages
displayed message/Condition/indiCates

Blocked Exhaust

The control system has detected the Blocked Exhaust
switch has open contacts - restricted/blocked vent piping,
the water heater is not venting properly.
Blocked Exhaust
Fault occurred 2 mins ago
The exhaust is blocked or
restricted. Ensure
condensate hose is draining.
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Important Service Reminder:
When performing any troubleshooting steps outlined in
this manual always consider the wiring and connectors
between components. Perform a close visual inspection
of all wiring and connectors to a given component before
replacement.

Blower Prover Failure

The control system has detected the Blower Prover
switch has closed contacts out of sequence; before
the Combustion Blower has been energized. See the
Sequence of operation on page 54 and the Sequence of
operation Flow Chart on page 55.
Blower Prover Failure
Fault occurred 2 mins ago
The blower prover switch is
closed out of sequence.
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62
BACK ADVANCED
BACK ADVANCED
Servicing should only be performed by a Qualified Service Agent
possible Causes - CheCK/repair
• Check the condensate drain on the water heater's
Exhaust Elbow, see Figure 3 on page 8 for location.
Water build up in the Exhaust Elbow will restrict the
venting system and cause this failure. Clear the
condensate drain line and ensure it is flowing freely.
• Check for restrictions - vent pipe size too small, too
many equivalent feet, or too many installed elbows
in the vent piping. Review venting installation section
of the Instruction Manual that came with the water
heater - see Table 1 on page 4 in this manual. Ensure
the vent/intake air piping has been installed within
manufacturers requirements.
• Ensure there is not a low point in the vent piping that
will allow water/condensate to collect and block the
vent piping.
• Check all wiring between the Blocked Exhaust
switch and the CCB's J6 Socket (page 41) pins 5 &
10. Perform close visual inspection of the pins inside
the plug and socket - ensure plugs and sockets are
mating properly and providing good contact. Repair/
replace anything worn or damaged.
• Perform the Pressure Switch Tests on page 31.
Replace the Blocked Exhaust switch if it is defective.
• Call the toll free support phone number on the back
cover of this manual for further assistance if the
problem has not been corrected after performing the
procedures outlined here.
• Check all wiring between the Blower Prover switch
and the CCB's J6 Socket (page 41) pins 6 & 7. Ensure
there are no shorted or pinched wires.
• Ensure there are no jumper wires installed on the
Blower Prover switch.
• Ensure there are no jumper wires installed between
the CCB's J6 Socket pins 6 & 7.
• Perform the Pressure Switch Tests on page 31.
Replace the Blower Prover switch if it is defective.
• Call the toll free support phone number on the back
cover of this manual for further assistance if the
problem has not been corrected after performing the
procedures outlined here.