284806-YIM-A-0107
Unitary Products Group
47
power is removed from the module either at the
unit or by resetting the room thermostat.
5.
Rollout Switch.
This switch is located above the main burners in
the control compartment, which in the event of a
sustained main burner rollout shuts off and locks
out both ignition controls closing both gas valves.
The ignition controls lock out furnace operation
until 24V power is removed from the controls either
at the unit or by resetting the room thermostat.
NOTE:
The auto reset rollout switch must reset before
allowing furnace operation.
6.
Auxiliary limit switch (AUX) -
This control is located inside the heat exchanger
compartment and is set to open at 190°F. It is a
manual reset switch. If AUX trips, then the primary
limit has not functioned correctly. Replace the pri-
mary limit.
FLASH CODES
The UCB will initiate a flash code associated with
errors within the system. Refer to UNIT CONTROL
BOARD FLASH CODES Table 29.
RESETS
Remove the call for heating by lowering the thermostat
setting lower than the conditioned space temperature.
This resets any flash codes.
HEAT ANTICIPATOR SETPOINTS
It is important that the anticipator setpoint be correct.
Too high of a setting will result in longer heat cycles
and a greater temperature swing in the conditioned
space. Reducing the value below the correct setpoint
will give shorter "ON" cycles and may result in the low-
ering of the temperature within the conditioned space.
START-UP (COOLING)
PRESTART CHECK LIST
After installation has been completed:
1.
Check the electrical supply voltage being supplied.
Be sure that it is the same as listed on the unit
nameplate.
2.
Set the room thermostat to the off position.
3.
Turn unit electrical power on.
4.
Set the room thermostat fan switch to on.
5.
Check indoor blower rotation.
•
If blower rotation is in the wrong direction.
Refer to Phasing Section in general informa-
tion section.
•
Check blower drive belt tension.
6.
Check the unit supply air (CFM). See "CHECKING
SUPPLY AIR CFM" on Page 39.
7.
Measure evaporator fan motor's amp draw.
8.
Set the room thermostat fan switch to off.
9.
Turn unit electrical power off.
TABLE 26: LIMIT CONTROL SETTING
Units
(Tons)
Capacity, MBH
Limit Control
Opens, ºF
Input
Output
15, 20 & 25
300
240
195
15, 20 & 25
400
320
195
FIGURE 20 - GAS VALVE AND CONTROLS
I G N . C O N T R O L # 1
I G N . C O N T R O L # 2
I G N I T O R # 1
G V 1
G A S
V A L V E
G V 2
G A S
V A L V E
I G N I T O R # 2
S E N S O R # 2
S E N S O R # 1
R O L L O U T S W .
B U R N E R C O M P A R T M E N T
TABLE 27: GAS HEAT ANTICIPATOR SETPOINTS
Gas Valve
Anticipator Setpoint
1st Stage
2nd Stage
Honeywell VR8440
0.30 amp
0.11 amp
White-Rodgers 36C68
