38
FIL
TER
AIR FLOW
CENTRAL
RETURN
GRILLE
RETURN
DUCT
FIL
TE
R
FILTER
SUPPORT
BRACKET
(Field Supplied)
FILTER
ACCESS
DOOR
Possible Upright Counterflow Filter Locations
Figure 44
H
ORIZONTAL
I
NSTALLATIONS
Filters must be installed in either the central return register
or in the return air duct work.
S
TARTUP
P
ROCEDURE
& A
DJUSTMENT
Furnace must have a 115 VAC power supply properly connected
and grounded. Proper polarity must be maintained for correct
operation. In addition to the following start-up and adjust-
ment items, refer to further information in
Operational Checks
section.
MIN.
57%
78%
(80%)
100%
IGNITION
UNIT CALL FOR HEAT ENDS
10 MINS.
8 MINS.
2 MINS.
Operation with Conventional 1-Stage Thermostat
(DIP switch selects 1-Stage heat)
Figure 45
Call for heat, thermostat energizes W1 on the furnace
control board (W2 input is ignored).
After a successful Light Off Sequence and expiration of
the Ignition Stabilization Period:
•
The furnace control board adjusts the firing rate to
35% (low fire rate).
•
After 2 minutes, the furnace control board
increases the firing rate to 57% at a rate of 1%
per second.
•
After 10 total minutes, the furnace control board
increases the firing rate to 78% at a rate of 1%
per second.
•
After 20 total minutes, the furnace control board
increases to 100% at a rate of 1% per second for
the remainder of the call for heat.
•
The circulator fan is adjusted to the appropriate
CFM, corresponding to the current firing rate.
MIN.
50%
60%
(80%)
70%
IGNITION
10 MINS.
8 MINS.
2 MINS.
Operation with Conventional 2-Stage Thermostat
(DIP switch selects 2-stage heat)
Figure 46
Call for 1st-Stage Heat - Thermostat contacts close R to W1.
After a successful Light Off Sequence and expiration of
the Ignition Stabilization Period:
•
The furnace control board adjusts to the low firing
rate.
•
After 2 minutes, the furnace control board
increases the firing rate to 50% for the next 8
minutes.
•
Thereafter, the furnace control board will increase
the firing rate 10%, at a rate of 1% per second,
every 10 minutes for the remainder of the call for
heat (See above figure).
•
The circulator fan is adjusted to the appropriate
CFM, corresponding to the current firing rate.
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