ADJUSTMENT OF TEMPERATURE RISE
The temperature rise, or temperature difference between the return air and the supply (heated) air from the furnace, must be within the range shown on the furnace rating plate and within the application limitations shown in Table 6, "Ratings & Physical / Electrical Data".
The supply air temperature cannot exceed the “Maximum Supply Air Temperature” specified in these instructions and on the fur- nace rating plate. Under NO circumstances can the furnace be allowed to operate above the Maximum Supply Air Temperature. Operating the furnace above the Maximum Supply Air Temperature will cause premature heat exchanger failure, high levels of Carbon Monoxide, a fire hazard, personal injury, property damage, and/or death.
After about 5 minutes of operation, determine the furnace temperature rise. Take readings of both the return air and the heated air in the ducts, about six feet (1.83 m) from the furnace where they will not be affected by radiant heat. Increase the blower speed to decrease the temperature rise; decrease the blower speed to increase the rise.
TWIN
Blower Off Delay Timer |
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Y/Y2 | DELAY | BLOWER OFF |
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FIGURE 40: Furnace Control Board
SECTION X: SAFETY CONTROLS
CONTROL CIRCUIT FUSE
A
BLOWER DOOR SAFETY SWITCH
Main power to the unit must still be interrupted at the main power disconnect switch before any service or repair work is to be done to the unit. Do not rely upon the interlock switch as a main power dis- connect.
Blower and burner must never be operated without the blower panel in place.
This unit is equipped with an electrical interlock switch mounted in the burner compartment. This switch interrupts all power at the unit when the panel covering the blower compartment is removed.
Electrical supply to this unit is dependent upon the panel that covers the blower compartment being in place and properly positioned.
All
Do not energize more than one motor speed at a time or damage to the motor will result.
ADJUSTMENT OF FAN CONTROL SETTINGS
This furnace is equipped with a
PARK PARK
HI COOL
HEAT
L1
XFMR
NEUTRALS
HUM
ROLLOUT SWITCH CONTROLS
These controls are mounted on the burner assembly. If the temperature in the area surrounding burner exceeds its set point, the gas valve is
PRESSURE SWITCHES
This furnace is supplied with two pressure switches, which monitor the flow through the combustion air/vent piping and condensate drain sys- tem. These switches
1.Blockage of vent piping or terminal.
2.Failure of combustion air blower motor.
3.Blockage of combustion air piping or terminals.
4.Blockage of condensate drain piping.
Johnson Controls Unitary Products | 31 |