5
Service Facts
M952-SF-4
INDOOR BLOWER TIMING
▲
WARNING
!
SAFETY HAZARD
BODILY INJURY CAN RESULT FROM HIGH VOLTAGE
ELECTRICAL COMPONENTS, FAST MOVING FANS,
AND COMBUSTIBLE GAS. FOR PROTECTION FROM
THESE INHERENT HAZARDS DURING INSTALLATION
AND SERVICING, THE ELECTRICAL SUPPLY MUST BE
DISCONNECTED AND THE MAIN GAS VALVE MUST
BE TURNED OFF. IF OPERATING CHECKS MUST BE
PERFORMED WITH THE UNIT OPERATING, IT IS THE
TECHNICIAN’S RESPONSIBILITY TO RECOGNIZE THESE
HAZARDS AND PROCEED SAFELY.
▲
CAUTION
!
The integrated furnace control is polarity sensitive. The
hot leg of the 115 VAC power must be connected to the
BLACK field lead.
Heating:
The integrated furnace control module controls the
indoor blower. The blower start is fixed at 45 seconds after ig-
nition. The FAN-OFF period is field selectable by dip switches
SW-2, #1 and #2 at 60, 100, 140, or 180 seconds. The factory
setting is 100 seconds.
W1-W2 stage delay (jumpered together) is field selectable by
dip switch SW-1, #1 and #2 at .5, 5, 10 or 15 minutes. The
factory setting is 10 minutes. (See wiring diagram).
Cooling:
The fan delay-off period is set by dip switches on the
Integrated Furnace Control. The options for cooling delay off
is field selectable by dip switches #5 and #6.
2nd Stage satisfied, 1st Stage still called:
W2 Comfort Control contacts open signaling that 2nd Stage
Heating requirements are satisfied.
The induced draft blower is reduced to low speed allowing
the 2nd Stage Pressure Switch contacts to open and the Gas
Valve is reduced to 1st Stage. The indoor blower motor is
reduced to low speed.
1st stage satisfied:
W1 Comfort Control contacts open signaling that 1st Stage
heating requirements are satisfied. The Gas Valve will close
and the induced draft blower will be de-energized. The indoor
blower motor will continue to run for the fan off period (Field
selectable at 60, 100, 140 or 180 seconds), then will be de-
energized by the control module.
Comfort Control call for heat (1-Stage Comfort Control)
W1/ W2 (jumpered) Comfort Control contacts close signaling
a call for heat. 1st Stage sequence of operation remains the
same as above. 2nd Stage Heat will energize after the Stage
delay timer (adjustable) has expired.
Comfort Control satisfied:
W1/ W2 (jumpered) contacts close signaling the control
module to close the Gas Valve. The induced draft blower is
switched to low speed and de-energized after the post purge
timer has expired. The indoor blower motor will continue to
operate after the flames are extinguished and then is switched
to low heat speed for the FAN-OFF period.
Table 1 and Figure 1 explain the delay-off settings:
Table 1
COOLING OFF - DELAY OPTIONS
SWITCH SETTINGS
SELECTION
NOMINAL
AIRFLOW
5 - OFF
6 - OFF
NONE
SAME
5 - ON
6 - OFF
1.5 MINUTES
100% *
5 - OFF
6 - ON
3 MINUTES
50%
5 - ON
6 - ON
**
50 - 100%
* - This setting is equivalent to BAY24X045 relay benefit
** - This selection provides
ENHANCED MODE,
which is a
ramping up and ramping down of the blower speed to provide
improved comfort, quietness, and potential energy savings.
See Wiring Diagram notes on the unit or in the Service Facts
for complete wiring setup for
ENHANCED MODE
. The graph
which follows, shows the ramping process.
Figure 1
OFF
50%
50%
80%
Dehumidify
Efficiency
Fast Coil Cooling
1
minute
3
minutes
7.5
minutes
100% if necessary
OFF
Summary of Contents for M952V060BD36AB
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Page 8: ...8 Service Facts M952 SF 4 M952 SCHEMATIC DIAGRAM2 From drawing D345191P01...
Page 9: ...9 Service Facts M952 SF 4 M952 WIRING DIAGRAM From drawing D345192...
Page 10: ...10 Service Facts M952 SF 4 M952 SCHEMATIC DIAGRAM From drawing D345192...
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