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AOS WPC - Tech Training 53 of 72 Ashland City, TN © 2007
Servicing should only be performed by a Qualified Service Agent
VF BOILER SERVICE MANUAL
ERROR MESSAGES (CONT)
DISPLAYED MESSAGE
CONDITION/INDICATES
CHECK/REPAIR
“Blower Prov Stg1”
Blower Is Starting
(If the blower is not starting go to the “Blower Prov
Stg1” Blower Is Not Starting
tables)
Helpful Troubleshooting Note:
The state of the contacts for the Low BPS can be
viewed in real time using the System Status Menu.
An asterisk will appear next to the “BlwLo Prv” menu
item when the switch contacts are closed. The
asterisk is not present when the switch contacts are
open.
Three conditions can cause this error message
when the blower is starting:
Normally Open Low Blower Prover or High Blower
Prover pressure switch contacts are not closing
during the pre or post purge operating states - or
within 5 minutes of call for heat being activated.
OR
Normally Open High Blower Prover pressure switch
contacts did not re-open after pre purge operating
state was completed. The High Blower Prover switch
is used to prove adequate purging of the combustion
chamber during pre and post purge cycles only. The
blower runs at approximately 5000 rpm during pre
and post purge operating states and at lower speeds
during all other operating states. High blower prover
switch contacts must close during the pre and post
purge states ONLY and open during all other
operating states.
OR
Normally Open Low Blower Prover pressure switch
contacts have opened during any operating state
when the blower should be running. IE: This can be
caused due to blower failure during the heating cycle
or if the pressure sensed by the switch rises above
the switches activation pressure for any reason. The
normally open contacts on both Blower Prover
switches close on a fall in pressure - the pressure
sensed must be in a vacuum.
Operational Note:
See blower prover switch information on page 24
and the Sequence of Operation on page 15.
Determine if Low BPS is causing the lock out.
• The normally open Low BPS (BPS = Blower
Prover Switch) switch must close its contacts
after the blower starts. The Low BPS contacts
must remain closed whenever the blower is run-
ning to avoid the “Blower Prov Stg1” lock out.
Turn power off; disconnect the two wires to the
Low BPS. See panel layout on page 24 to deter-
mine which is the Low BPS.
Prepare a jumper wire to jumper between the
two wires just disconnected. Turn the boiler
back on, ensure a call for heat is present.
AFTER the blower motor starts jumper the two
(24 VAC) wires together carefully. Do not let the
wire ends touch any grounded surface.
Notice whether or not the boiler will continue
operation to the igniter warm up period when
the igniter is energized or locks out again on
“Blower Prov Stg1.” Clip an amp meter around
one of the igniter wires to see when the igniter
warm up period begins.
If the boiler will not continue on to the igniter
warm up period and locks out again on “Blower
Prov Stg1” before the igniter is energized; the
Low BPS is not causing the lock out. Turn off
power to the boiler and reconnect the wires to
the Low BPS. Continue on to: “Determine if
High
BPS is causing the lock out” in the table on
page 54.
If the boiler operation continues on to the igniter
warm up period without lock out. The Low BPS
is causing the lock out condition. Continue on to
the: “Pressure Reading Test” on page 55.