Johnson Controls TM9V MP Section Ix Safety Controls, UIM-B-0509, Adjustment Of Temperature Rise

438335-UIM-B-0509

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 7 “ELECTRICAL AND PERFORMANCE 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.

VARIABLE SPEED MOTORS

The variable speed motor must be configured so the blower will provide a sufficient airflow so that the furnace operates with in the temperature rise range on the rating plate and within the application limitations shown in Table 7 in these Instructions.

ADJUSTMENT OF FAN CONTROL SETTINGS

Heating Indoor Fan Off Delay

This furnace is equipped with a time-on/time-off heating fan control. The fan on delay is fixed at 30 seconds. The fan off delay has 4 settings (60, 90, 120 and 180 seconds). The fan off delay is factory set to 120 sec- onds. The fan-off setting must be long enough to adequately cool the furnace, but not so long that cold air is blown into the heated space. The fan-off timing may be adjusted by positioning the jumper on two of the four pins as shown in Figure 41.

BLOWER OFF	HI HEAT DELAY	CONTINUOUS FAN
DELAY JUMPER	JUMPER	SPEED JUMPER

LOW VOLTAGE

TERMINALS

BLOWER SPEED

JUMPERS

HEAT

DELAY

JUMPER

DEHUMIDISTAT JUMPER COOLING PROFILE JUMPER

FIGURE 41: Furnace Control Board

SECTION IX: SAFETY CONTROLS

CONTROL CIRCUIT FUSE

A 3-amp fuse is provided on the control circuit board to protect the 24- volt transformer from overload caused by control circuit wiring errors. This is an ATO 3, automotive type fuse and is located on the control board.

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.

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 de-energized. The operation of this control indicates a malfunction in the combustion air blower, heat exchanger or a blocked vent pipe con- nection. Corrective action is required. These are manual reset controls that must be reset before operation can continue.

PRESSURE SWITCHES

This furnace is supplied with three pressure switches, which monitor the flow through the combustion air/vent piping and condensate drain sys- tem. These switches de-energize the gas valve if any of the following conditions are present. Refer to SECTION VI, "CONDENSATE PIPING AND FURNACE VENTING CONFIGURATION" for tubing connections.

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.

32 Johnson Controls Unitary Products