21
FILTERS - READ THIS SECTION BEFORE INSTALLING THE
RETURN A IR D UCTWORK
Filters must be used with this furnace. Discuss filter maintenance
with the building owner. Filters do not ship with this furnace, but
must be provided by the installer. Filters must comply with UL900
or CAN/ULCS111 standards. If the furnace is installed without
filters, the warranty will be voided.
NOTE: An undersized opening will cause reduced airflow. The
bottom return is set up as a knock out.
UPRIGHT I NSTALLATIONS
Depending on the installation and/or customer preference,
differing filter arrangements can be applied. Filters can be
installed in the central return register or a side panel external filter
rack kit (upflows), or the ductwork above a downflow furnace. As
an alternative, a media air filter or electronic air cleaner can be
used as the requested filter.
CIRCULATION A IR F ILTERS
One of the most common causes of a problem in a forced air
heating system is a blocked or dirty filter. Circulating air filters
must be inspected monthly for dirt accumulation and replaced if
necessary. Failure to maintain clean filters can cause premature
heat exchanger failure.
A new home may require more frequent replacement until all
construction dust and dirt is removed. Circulating air filters are to
be installed in the return air duct external to the furnace cabinet.
FURNACE INPUT FILTER SIZE TYPE
45M
160 in
2
permanent
70M
241 in
2
permanent
90M
320 in
2
permanent
115M
400 in
2
permanent
140M
370 in
2
permanent
45M
320 in
2
disposable
70M
483 in
2
disposable
90M
640 in
2
disposable
115M
800 in
2
disposable
140M
738 in
2
disposable
PERMANENT NOMINAL 600 F.M. FACE VELOCITY
DISPOSABLE NOMINAL 300 F.M. FACE VELOCITY
MINIMUM FILTER SIZES
HORIZONTAL I NSTALLATIONS
Filters must be installed in either the central return register or in
the return air duct work.
XI. SEQUENCE OF OPERATION
(INTEGRATED IGNITION CONTROL)
Refer to Timing Charts for sequencing.
POWER UP
• 115 VAC power applied to furnace.
• Integrated ignition control performs internal checks.
• Integrated ignition LED will light.
• Integrated ignition control monitors safety circuits
continuously.
• Furnace awaits call from thermostat.
HEATING MODE
(MODE DIP SWITCH IS SET TO “1 STG” POSITION)
The normal operational sequence in heating mode is as follows:
• R and W thermostat contacts close, initiating a call for heat.
• Integrated control module performs safety circuit checks.
• Induced draft blower is energized for 15 second pre-purge
period causing pressure switch contacts to close.
• Igniter warm up begins after 15 second prepurge expires.
• Low and high-stage gas valves open at end of igniter warm
up period, delivering gas to burners and establishing flame.
• Integrated control module monitors flame presence. Gas
valve will remain open only if flame is detected.
• Circulator blower is energized on high heat speed following
a fixed thirty second blower on delay. Electronic air cleaner
terminals are energized with circulator blower.
• Furnace operates; integrated control module monitors
safety circuits continuously.
• R and W thermostat contacts open, completing the call for
heat.
• Gas valve closes, extinguishing flame.
• Induced draft blower is de-energized following a fifteen
second post purge.
• The circulator blower remains on high speed for thirty
seconds, then switches to low heat speed for the remainder
of the selected heat off delay period. For example, the
selected heat off delay period is 150 seconds. The circulator
blower operates at high heat for 30 seconds and at low
speed for 150 - 30 = 120 seconds.
• Furnace awaits the next call from thermostat.
(MODE DIP SWITCH IS SET TO “2 STG”POSITION)
The normal operational sequence in sequence is as follows:
• R and W thermostat contacts close, initiating a call for heat.
• Integrated control module performs safety circuit checks.
• Induced draft blower is energized for 15 second prepurge
period causing pressure switch contacts to close.
• Igniter warm up begins after 15 second prepurge expires.
• Low and high-stage gas valves open at end of igniter warm
up period, delivering gas to burners and establishing flame.
• High-stage gas valve closes after five seconds; low-stage
gas valve remains open.
• Integrated control module monitors flame presence. Gas
valve will remain open only if flame is detected.
• Circulator blower is energized on low heat speed following
a fixed thirty second blower on delay. Electronic air cleaner
terminals are energized with circulator blower.
• Furnace is now operating in low-stage heating mode.
• Furnace operates; integrated control module monitors
safety circuits continuously.
• If low-stage delay period expires, control will shift operation
from low-stage heating mode operation to high-stage
heating mode operation. Control will energize circulator
blower high heat speed and high stage gas valve.
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