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the R-W/W1
circuit.
Accurate
amp draw
measurements
can be
obtained
only at the thermostat
subbase
terminals
R and W.
The thermostat
and anticipator
should NOT be in the circuit while
measuring
current.
If thermostat
has no subbase,
the thermostat
must
be disconnected
from
R and W/WI
wires
during
current
measurement.
Fig. 63 illustrates
an easy method
of obtaining
thermostat
amp
draw
measurements.
The
amp
reading
should
be
taken
after
blower
motor has started and furnace
is operating
in low-heat.
1. To operate
furnace
in low-heat,
turn setup switch
SWl-2
to ON position
(See Fig. 33) and connect
ammeter
leads
across thermostat
subbase
R-W.
2. See thermostat
manufacturer's
instructions
for adjusting
the heat anticipator
and for varying
heating
cycle length.
NOTE:
When using an electronic
thermostat,
set cycle rate for 3
cycles per hr.
3. Return
setup switch
SWI-2
to OFF position
and replace
thermostat
on subbase.
Check
Safety Controls
This
section
covers
the safety
controls
that nmst
be checked
before
the installation
is complete.
The flame sensor,
gas valve,
and pressure
switches
were all checked
in the Start-up
procedure
section as part of normal operation.
Check
Primary
Limit
Control
This control
shuts
off the gas control
system
and energizes
the
air-circulating
blower
motor if furnace
overheats.
1. The recommended
method
of checking
this limit control is
to gradually
block
off return air after furnace
has been op-
erating
for a period of at least 5 minutes.
2. As soon as limit control
has shut off burners,
a status code
33 will appear on furnace
control.
3. The return-air
opening
should
be unblocked
to permit
normal
air circulation.
By using
this
method
to check
the
limit
control,
it can be
established
that the limit is functioning
properly
and the furnace
will operate
safely if there is a restricted
return-air
duct or motor
failure.
If the limit control
does not function
during
this test, the
cause nmst be determined
and corrected.
Check
Pressure
Switches
This control
proves operation
of the draft inducer.
Check
switch
operation
as follows:
1. Turn off l15-v
power
to furnace.
2. Remove
control
access door and disconnect
inducer motor
12-pin
wire harness
at inducer
motor.
3. Turn on l15-v
power
to furnace.
4. Set thermostat
to "call for heat." When
pressure
switches
are functioning
properly,
status code 42 will flash
on fur-
nace control
approximately
20 sec after thermostat
switch
is closed.
If either a status code 31 or 32 is flashed
when
inducer
motor
is disconnected,
the furnace
will shut itself
down
immediately.
Determine
the
reason
pressure
switches
did not function
properly
and correct
the condi-
tion.
5. Turn off l15-v
power
to furnace.
6. Reconnect
inducer
motor
wire harness.
Reinstall
furnace
access door.
7. Turn on l15-v
power
to furnace.
8. Reset thermostat
to desired
temperature.
CHECKLIST
1. Put away tools and instruments.
Clean up debris.
2. Verify flame rollout manual
reset switch
has continuity.
3. Verify that blower
and main access doors
are properly
in-
stalled.
4. Cycle test furnace
with room thermostat.
5. Check operation
of accessories
per manufacturer's
instruc-
tions.
6. Review
User's
Manual
with owner.
7. Leave literature
packet near furnace.
THERMOSTAT
SUBBASE
TERMINALS
WITH
THERMOSTAT
REMOVED
(ANITICIPATOR,
CLOCK, ETC.,
MUST BE OUT OF CIRCUIT.)
HOOK-AR(
AMMETER
FROM UNIT 24-V
CONTROL TERMINALS
EXAMPLE:
5.0 AMPS ON AMMETER
= 0.5 AMPS FOR THERMOSTAT
10 TURNS AROUND
JAWS
ANTICIPATOR
SETTING
Fig. 63 - Amp Draw
with Ammeter
A96316
60
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