AOS WPC - Tech Training 45 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
“Low AC Voltage”Power supply polarity is reversed. Line voltage to
boiler is less than 90 VAC.
• Ensure power supply polarity is not reversed
and boiler is properly grounded.
• Perform Power Supply Test Procedure (page
40) - correct any problems indicated by test.
• Check incoming power supply, wiring, and all
line voltage connections on the boiler and at the
breaker or disconnect switch - repair/restore
115 - 120 VAC power supply to boiler.
“Low 24 VAC”Voltage from transformer is less than 18 VAC.
Important Service Reminder:
When performing any troubleshooting steps outlined
in this service 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.
Failure to perform this critical step or failing to
perform this step thoroughly often results in
needless down time, unnecessary parts
replacement, and customer dissatisfaction.
• Check 120 VAC to transformer. Check for 115 -
120 VAC between pins 3 & 6 of the J1 socket on
the PDB (page 38). Perform this test with the
wiring harness plugged into the J1 Socket.
• Ensure transformer is 100 VA rated - replace
transformer if rating is less than 100 VA.
• Secure power to boiler; temporarily disconnect
load wiring from secondary coil on transformer.
Turn power back on and check voltage at sec-
ondary coil - if secondary (24 VAC) voltage
remains low - replace transformer.
• Check all 24 VAC wiring for worn/damaged con-
nections or wires - replace/repair as necessary.
• Replace transformer.
“Low Water”Water is not being sensed by optional LWCO (low
water cutoff) device’s sensor.
• Ensure there is water in the lines/boiler.
• Remove and clean LWCO sensor.
• If the SW1 #6 dip switch is configured for LWCO
present when the optional control is not installed
on the boiler. This will return a “Low Water” error
message. Check “Config Settings” menu screen
(see page 9) to confirm correct LWCO dip
switch setting. Set SW1 #6 dip switch on the
MCB correctly (see page 30).
• Check all wiring, plugs, and sockets (J4 socket
on the MCB board - see page 28) for good con-
nections - repair/replace damaged/worn parts.
“Low Gas”Supply gas pressure has dropped below pressure
activation point of the Low Gas Pressure switch.
Low gas pressure switch is standard on VF boilers.
SW1 dip switch #7 is set to “on” to configure the
control system to monitor this switch (page 30).
• Check supply gas pressure with boiler firing at
100%. Ensure supply pressure is maintained
above 4.0" W.C. for natural gas and 6.4" W.C.
for propane - replace low gas switch if supply
pressures are maintained above activation point
at 100% firing rate and error message persists.
• Ensure gas line is properly sized. - adjust gas
supply pressure at regulator serving the boiler.