Set Thermostat Heat Anticipator; Check Safety Controls - Carrier 58TUA Installation, Start-Up, And Operating Instructions Manual

Fig. 14—Burner Flame
(1.) Gas input for low- and high-fire operation.
(2.) Derate for altitude if applicable.
(3.) Return and supply ducts for excessive restrictions
causing static pressures greater than 0.50-in. wc.
c. Adjust air temperature rise by adjusting blower speed.
Increase blower speed to reduce temperature rise. Decrease
blower speed to increase temperature rise. For high fire,
speed selection can be med-high or med-low (factory
setting). For low fire, speed selection can be low (factory
setting) or med-low if high-fire speed selection is med-
high.
Disconnect the electrical power before changing the speed
tap. A failure to follow this warning can cause personal
injury.
d. To change motor speed selection for high heat, remove
blower motor lead from control HIGH-GAS-HEAT termi-
nal (See Fig.10. and 12.). Select desired blower motor
speed lead from 1 of the other terminals and relocate it to
the HIGH-GAS-HEAT terminal. (See Table 10 for lead
color identification.) Reconnect original lead to the PARK
terminal. Follow this procedure for proper selection of cool
and low-gas-heat speed selection.
Table 10—Speed Selection
COLOR SPEED
White Common
Black High
Yellow Med-High
Blue Med-Low
Red Low*
* Continuous blower speed
Recheck the temperature rise. It must be within the limits
specified on the unit rating plate. Recommended operation is
at midpoint of rise range or above.

3. Set thermostat heat anticipator.

a. When using a nonelectronic thermostat, the thermostat heat
anticipation must be set to match the amp draw of the
electrical components in the R-W/W1 circuit. Accurate
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AS SHIPPED
Com
Cool
Park
High-Gas Heat
Low-Gas Heat
16
amp draw readings can be obtained at the wires normally
connected to thermostat subbase terminals R and W/W1.
Fig. 15 illustrates an easy method of obtaining the actual
amp draw. The amp reading should be taken after the
blower motor has started and the furnace is operating in
low fire. To operate the furnace in low fire, first move
SW-2 to ON position, THEN connect the ammeter wires as
shown in Fig. 15. The thermostat anticipator should NOT
be in this circuit while measuring the current. If the
thermostat has no subbase, the thermostat MUST be
disconnected from the R and W/W1 wires during the
current measurement. Return SW-2 to final desired location
after completing the reading. See the thermostat manufac-
turer's instructions for adjusting the heat anticipator.
b. When using an electronic thermostat, set the cycle rate for
3 cycles per hr.

CHECK SAFETY CONTROLS

The flame sensor, gas valve, and pressure switches were all
checked in the Start-up section as part of normal operation.
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
will operate if there is a motor failure.
2. Check draft safeguard switch.
The purpose of this control is to cause safe shutdown of the
furnace during certain blocked vent conditions.
a. Disconnect power to furnace and remove vent connector
from furnace flue collar. Be sure to allow time for vent
connector pipe to cool down before removing.
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
R Y W G
10 TURNS
FROM UNIT 24-VOLT
TERMINAL BLOCK
5.0 AMPS ON AMMETER
EXAMPLE:
10 TURNS AROUND JAWS
Fig. 15—Amp Draw Check With Ammeter
b. Restore power to furnace and set room thermostat above
room temperature.
HOOK-AROUND
VOLT/AMMETER
= 0.5 AMPS FOR THERMOSTAT SETTING
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