A
M-TRAC1
IOM-55
May 2019
14
SETPOINT (SPC)
Check the wiring diagram to determine if the M-TRAC1 is using the face mounted setpoint dial
or an optional remote mounted setpoint dial. The most commonly used remote control panel
includes fan and heat on/off switches and a setpoint dial. A jumper will be installed across
terminals S and SP if the M-TRAC1 is using its built in setpoint dial.
1.
Disable any external temperature resets (DIP switch 1 off) or lower the room thermostat
settings so there is no call for additional heat.
2.
Use a voltmeter to measure the Vdc output on the SPC measurement point.
3.
Compare to the Setpoint dial and adjust the SP CAL POT (located near the face mounted
setpoint dial) so they match (1 Vdc = 10°C).
4.
Turn DIP switch 1 on, or return the room thermostat to its normal position.
Note: If the adjustments have no effect on the discharge temperature, the set point may be
under the authority of the maximum set point limiting POT (SP LMT).
DISCHARGE AIR TEMPERATURE (DTEMP)
The discharge sensor must be located so that its temperature remains stable. Due to the
nature of direct fired appliance, the air temperature leaving the supply blower is often very
stratified. It is important to understand that the supply blower does not significantly mix the
air. As well, the stratification pattern will change with different firing rates, wind conditions,
ducting and blower configurations.
Field conditions may result in differences between the sensed temperature and the actual
temperature. Adjusting the location of the discharge sensor a few inches will often correct
temperature differences. If a section of duct is connected to the discharge opening, the sensor
may be moved downstream up to 10 ft. (3 meters). Moving the sensor too far downstream
may result in sensing lag, which could compound control error.
1.
Accurately measure the temperature at the discharge air sensor.*
2.
Compare the temperature to the DTEMP test point voltmeter reading.
3.
Match the readings by adjusting the CAL DTEMP POT (located near terminal Q1,
1 Vdc = 10°C).
* The discharge sensor may be temporarily replaced with a resistor to confirm calibration.
Refer to the Sensor Table, or use a 1kΩ resistor for 21.1°C (70°F) or a 2 kΩ resistor is using dual
sensors (using terminal Q2). Do not leave the resistor in place for normal operation!
