15
When the furnace is heating, the temperature of the return
air entering the furnace must be between 55°F and 100°F.
When a furnace is installed so that supply ducts carry air
circulated by furnace to areas outside the space containing
the furnace, the return air shall also be handled by a duct
sealed to the furnace casing and terminating outside the
space containing the furnace.
FILTERS - READ THIS SECTION BEFORE
INSTALLING THE RETURN AIR DUCTWORK
Filters must be used with this furnace. Discuss filter main-
tenance 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.
Guide dimples locate the side return cutout locations. Use
a straight edge to scribe lines connecting the dimples. Cut
an opening to match the dimensions of these lines.
NOTE:
An undersized opening will cause reduced airflow.
The bottom return is set up as a knock out.
For air delivery of less than 1800 CFM, use a one side or
bottom return.
For air delivery of 1800 CFM or higher, use either two-sided
returns or a one-sided return with a bottom return.
To ensure proper unit performance follow the filter sizes
given in the Specifications Sheet.
UPRIGHT INSTALLATIONS
Depending on the installation and/or customer preference,
differing filter arrangements can be applied. Filters can be
installed in the central return register, the bottom of the
blower compartment (upflows), a side panel external filter
rack kit - EFR01 (upflows), inside the side panel (upflows),
or the ductwork above a counterflow furnace. As an
alternative a media air filter (MAC1) or electronic air cleaner
(EAC5) can be used as the requested filter. Review and
follow the filter sizes given in the Specifications Sheet to
ensure proper unit performance. The following figures
show possible filter locations.
CENTRAL
RETURN
GRILLE
FI
LT
E
R
SIDE RETURN
EXTERNAL FILTER
RACK KIT
(EITHER SIDE)
FI
LT
E
R
FI
LT
E
R
SIDE RETURN
INTERNAL FILTER
RETENTION
(EITHER SIDE)
AIR FLOW
F I L T E R
Figure 26
Possible Upright Upflow
Filter Locations
AIR FLOW
FILTE
R
FI
LT
E
R
FI
LTE
R
FILTER
ACCESS
DOOR
CENTRAL
RETURN
GRILLE
RETURN
DUCT
FILTER
SUPPORT
BRACKET
(PROVIDED)
Figure 27
Possible Upright Counterflow
Filter Locations
HORIZONTAL INSTALLATIONS
Filters must be installed in either the central return register
or in the return air duct work.
Refer to the Specification Sheet for recommended mini-
mum filter sizes.
VIII. Sequence of Operation
Refer to Timing Charts for sequencing.
NORMAL HEATING SEQUENCE
1. Thermostat calls for heat (high heat or low heat).
2. The induced draft blower is energized on high speed for
a 10 second prepurge.
3. The induced draft blower is energized on low speed.
4. The igniter is energized and is allowed to preheat for 17
seconds.
5. The gas valve is energized delivering gas to the burners
at the low stage heat flow rate.
6. The control checks for a signal from the flame sensor
within seven seconds after the gas valve is energized
(opens). Gas will only continue to flow if a signal is
present.
7. The control checks the thermostat to see whether the
call for heat is for low stage heat or high stage heat. If
the call is for high stage heat, the induced draft blower
is switched to high speed and the gas valve is energized
on high flow rate.
8. The control waits 30 seconds and turns on the air
circulation blower to the appropriate speed (high heat
speed for high heat or low heat speed for low heat). On
some Amana models, the high heat air circulator speed
may be the same as the low heat circulator speed.
These models are factory shipped to be within the rise
range on both stages with the same air circulator
speed.
