Periodic Servicing Requirements - American Standard UHMB060ACV3VB Series Service Facts

PS-3 Inducer Learning Routine
Note:
Stage 1 = 40% (low) heat, Stage 2 = 100% (high) heat
•
When the furnace IFC receives a digital signal for
100% (high) heat from the comfort control it will begin
the PS-3 inducer learning routine.
•
The furnace will start the heating cycle in 65% (medi-
um) heat, if not already on, and then begins the PS-3
inducer learning routine.
•
The furnace IFC will send a digital signal to the vari-
able speed inducer drive to run the inducer motor at
the preset factory 100% (high) heat RPM.
•
The furnace IFC waits for PS-3 pressure switch to
close. A 24 Volt AC signal is sent to the furnace IFC
when the pressure switch closes.
•
If PS-3 does not close at the factory preset 100%
(high) heat RPM, the furnace IFC will continue to sig-
nal the variable speed inducer drive to increase the
inducer speed in steps until PS-3 closes or until the
maximum RPM for 100% (high) heat is reached.
•
The furnace IFC enters a time delay so that the heat
exchanger and the recuperative cell warm up to their
high heat operating temperature. At the end of this
time delay, the inducer discharge air temperature
will be at its high heat operating temperature and the
density of the products of combustion will be stabi-
lized.
•
The furnace will now signal the variable speed
inducer drive to reduce the inducer speed in steps
until PS-3 opens.
•
When PS-3 opens, the furnace IFC will NOTE the in-
ducer motor RPM.
•
The furnace IFC then adds an additional number of
RPM to the 100% (high) heat inducer motor NOTED
RPM until PS-3 closes.
• The furnace IFC now stores this learned inducer oper-
ating RPM for 100% (high) heat in its memory.
• The furnace IFC will use this stored learned inducer
operating RPM for 100% (high) heat calls it receives
in the future.
•
If PS-3 is not closed when the inducer reaches its
maximum RPM, the furnace IFC will signal the vari-
able speed inducer drive to reduce the inducer Motor
speed in steps to its low heat LEARNED SPEED.
•
The furnace IFC flashes its Red Fault LED three
times repeatedly. The furnace IFC will keep
operating at low heat for 10 minutes and then retry
the PS-3 learning routine.
UHM-DHM-SF-1V-EN
Service Facts
INDOOR BLOWER TIMING
Heating:
The Integrated Furnace Control module
controls the Indoor Blower. The Blower
start is fixed at 45 seconds after ignition.
The FAN-OFF period is field selectable
via the User Interface menu at 60, 100,
140, or 180 seconds. The factory setting is
100 seconds.
Cooling: Continuous Fan mode is 50% of the cool-
ing CFM. This is a selectable range on
the Comfort Control menu.
When in communicating mode, see Use Interface Menu
in furnace Installer's Guide.

PERIODIC SERVICING REQUIREMENTS

WARNING
!
Disconnect power to the unit before removing the
Blower door. Allow a minimum of 10 seconds for IFC
power supply to discharge to 0 volts.
Failure to follow this warning could result in property
damage, personal injury or death.
WARNING
!
CARBON MONOXIDE POISONING HAZARD
Failure to follow the service and/ or periodic
maintenance instructions for the Furnace and venting
system, could result in carbon monoxide poisoning or
death.
1. GENERAL INSPECTION – Examine the furnace
installation annually for the following items:
a. All flue product carrying areas external to the
Furnace (i.e. chimney, vent connector) are clear
and free of obstruction. A vent screen in the end of
the Vent (flue) Pipe must be inspected for blockage
annually.
b. The vent connector is in place, slopes upward
and is physically sound without holes or excessive
corrosion.
c. The return air duct connection(s) is physically
sound, is sealed to the Furnace and terminates
outside the space containing the Furnace.
d. The physical support of the Furnace should be
sound without sagging, cracks, gaps, etc., around
the base so as to provide a seal between the
support and the base.
e. There are no obvious signs of deterioration of the
Furnace.
2. FILTERS – Filters should be cleaned or replaced
(with high velocity filters only), monthly and more
frequently during high use times of the year such as
midsummer or midwinter.
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