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4. Heat P ump Mode
When installed witha heat pump, the fl/mace c ontrol auto-
matically changes
the timing sequence
toavoid l ong blower
offtimes during d emand defrost cycles. When t heR-to-W-
and-Y or R-to=W-and-Y-and-G
circuits a reenergized
the
Nmace control CPU willcontinue toturn onthe blower motor
BLWM at HEAT speed, andbegin a heating cycle.
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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