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→Fig. 17—Redundant Automatic Gas Control Valve
BURNER FLAME
MANIFOLD
Fig. 18—Burner Flame
WARNING: Disconnect the electrical power before
changing the speed tap. Failure to follow this warning
could result in personal injury.
d. To change blower motor speed selections for heating
mode, remove blower motor lead from control HEAT
terminal. (See Fig. 14.) Select desired blower motor
speed lead from 1 of the other terminals and relocate it
to HEAT terminal. See Table 10 for lead color identifi-
cation. Reconnect original lead on SPARE terminal.
Follow this same procedure for proper selection of COOL
speed selection.
CAUTION: Recheck temperature rise. It must be within
limits specified on unit rating plate. Recommended op-
eration is at midpoint of rise or above.
3. Set thermostat heat anticipator.
The thermostat heat anticipator must be set to match the
amp draw of the electrical components in the R-W circuit.
Accurate amp draw readings can be obtained at thermostat
NOTE: When using an electronic thermostat, set cycle rate for 3
cycles per hr.
A00238
BURNER
A89020
E. Check Safety Controls
The flame sensor, gas valve, and pressure switch were all checked
in the Start-Up Procedures section as part of normal operation.
—19—
TABLE 10—SPEED SELECTOR
COLOR
SPEED
Black
High
Yellow
Medium-High
(When present)
Blue
Medium-Low
Red
Low
White
Common
subbase terminals R and W. Fig. 19 illustrates an easy
method of obtaining the actual amp draw. The amp reading
should be taken after the blower motor has started. See the
thermostat manufacturer's instructions for adjusting the
heat anticipator and for varying the heating cycle length.
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
(ANITICIPATOR, CLOCK, ETC.,
MUST BE OUT OF CIRCUIT.)
R Y W G
10 TURNS
FROM UNIT 24-V
CONTROL TERMINALS
5.0 AMPS ON AMMETER
EXAMPLE:
10 TURNS AROUND JAWS
Fig. 19—Amp Draw Check With Ammeter
1. Check primary limit control.
This control shuts off the combustion control system and
energizes the circulating-air blower motor if the furnace
overheats.
The preferred method of checking the limit control is to
gradually block off the return air after the furnace has been
operating for a period of at least 5 minutes. As soon as the
limit has shut off the burners, the return-air opening should
be unblocked. By using this method to check the limit
control, it can be established that the limit is functioning
properly and operates if there is a motor failure.
2. Check blocked vent safeguard switch.
The purpose of this control is to permit the safe shutdown
of the furnace during certain blocked vent conditions.
a. Disconnect power to furnace and remove vent connector
from furnace outlet collar. Be sure to allow time for vent
pipe to cool down before removing.
FACTORY-
ATTACHED TO
COOL
SPARE
HEAT
SPARE
L2/COM
HOOK-AROUND
AMMETER
0.5 AMPS FOR THERMOSTAT
=
ANTICIPATOR SETTING
A96316
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