4.HeatPumpMode
Wheninstalledwithaheatpump,thefl/macecontrolauto-
maticallychangesthetimingsequencetoavoidlongblower
offtimesduringdemanddefrostcycles.WhentheR-to-W-
and-Yor R-to=W-and-Y-and-Gcircuitsareenergizedthe
NmacecontrolCPUwillcontinuetoturnontheblowermotor
BLWMatHEATspeed,andbegina heatingcycle.The
blower motor BLWM will remain on until the end of the
prepurge period, then shut off %r 24 seconds then come back
on at HEAT speed. When the W input signal disappears, the
Nrnace control begins a normal inducer post-purge period and
the blower switches to (OOL speed after a 3 second delay. If
the R=to-W-and-Y-and=G signals disappear at the same time,
the blower motor BLWM will remain on for d-_e selected
blower-OFF delay period. If the R=to-W-and=Y signals disap-
pear, leaving the G signal, the blower motor BLWM will
continue running the blower motor BLWM at HEAT speed
after the selected blower-OFF delay period is completed.
( OMPONENT TEST
NOTE: The furnace control component test allows all compo=
nents to run for a short time; except the gas valve and humidifier
terminal HUM are not energized for safety reasons. The EAC-1
terminal is energized when the blower is energized. This feature
helps diagnose a system problem in case of a component f_ilure.
The component test fcatu, e will not operate if any thermostat
signal is present at the control and not until all time delays are
completed.
To Begin Component Self=Test:
ELECTRICAL SHOCK HAZARD
Failure to %ltow d_is warning could result in electrical shocL
personal injury, or death.
Blower access panel door switch opens l15=v power to
control center No component operation can occur. Caution
must be taken when manually closing this switch for service
purposes.
1. Remove blower access door.
2. Disconnect the fl-_ermostat R lead from furnace control.
3. Manually close blower door switch.
4. For approximately 2 sec, short 0umper) the COM-24V terminal
on control to the TEST/TWIN 3/16=inch quick-connect termi=
hal on control until the LED goes out. Remover jumper from
terminals. (See Fig. 33.)
NOTE: If TEST/TWIN and (o_,>24v terminals are jumpered
longer than 2 sec, LED will flash rapidly and ignore component
test request
Component test sequence is as fbllows:
a. LED will display previous status code 4 dines.
b. Inducer motor starts and continues to run until Step g of
component test sequence
c. After 7 seconds the hot surfSce igniter is energized for 15
sec_ then off'.
d. Blower motor operates on HEAT speed for 10 sec.
e. Blower motor operates on (OOL speed for 10 sec.
£ Inducer motor stops.
5. iReconnect R lead to furnace contiot, remove tape from blower
door switch, and re=install blower door.
6. Operate thmace per instruction on outer door.
39
7 Verify flmaace shut down by lowering thermostat setting
below room temperature
8 Verify that flmaace restarts by raising thermostat setting above
room temperature.
Step 5--Adjustments
SET GAS INPUT RATE
Furnace gas input rate on rating plate is %r installations at ahimdes
up to 2000 It,
In the [,SA, the input ratings fbr ahitudes above 2000 ft must be
reduced by 2 pc*cent %* each 1000 ft above sea tevel,
In Canada, the input ratings must be de*ated by 5 percent fbr
ahimdes of"2000 ft to 4500 ft above sea level,
Furnace input rate must be within 2 percent of input on furnace
rating plate adjusted fbr altitode.
1 Determine natural gas orifice size and manifold pressure fbr
correct input
a Obtain average gas heat value (at installed altitude) from
local gas supplier
b Obtain average gas specific gravity flora local gas supplier.
c Verif) furnace model. Table 11 can only be used fbr model
58MSA furnaces
d Find installation ahimde in Table 11
NOTE: For Canadian altitudes of 2001 to 4500 It, use USA,
altitudes of"2001 to 3000 ft in Table 11,
e Find closest natural gas heat value and specific gravity on
Table 11
£ Follow heat value and specific gravity lines to point of
intersection to find orifice size and mani%ld pressure
settings for proper operation
REGULATOR
_SEAL CAP
REGULATOR
/_ADJUSTMENT
SCREW
INLET
PRESSURE TAP
REGULATOR SPRING
(PROPANE - WHITE, 6 TURNS
NATURAL - SILVER 10 TURNS)
GAS PRESSURE
REGULATOR
ADJUSTMENT
A03142
Fig. 4g--Redundant Automatic Gas VNve
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