Technical Instructions
Document Number 155-066P25
October 26, 2010
Page 6
Siemens Industry, Inc.
TH 192 HC
Thermostat Details
Figure 5. TH 192 HC Thermostat Details.
Thermometer
Calibration
1. Use a test thermometer to read the current room temperature.
2. Place a screwdriver in the center of the thermometer assembly (Figure 5). Carefully
rotate thermometer assembly until pointer tip indicates the correct room temperature.
NOTE:
Avoid breathing on or touching the bimetal spiral since this influences the
temperature reading.
Changeover Point
Adjustment
The changeover point is factory set to occur between 19 and 22 psi (131 and 152 kPa). The
changeover point can be field adjustable to occur between 14 and 22 psi (96 and 152 kPa).
1. Connect pressure gauge or manometer to measure supply pressure to thermostat. Use
30 psi (207 kPa) supply through a positioning switch so pressure can be fully variable.
2. Determine current change over point. Turn cooling dial so cooling and heating control
pressures are different. Then note the changeover point on the control gauge as the
supply pressure changes.
3. Remove thermometer for access to changeover adjustment screw. Use a 1/16’ Allen
Hex Key to adjust changeover adjustment screw as follows:
a. If changeover is too high, turn off supply pressure and rotate changeover
adjustment screw clockwise. One turn decreases changeover point by about 3 psi
(20 kPa). Turn on supply pressure and recheck to verify new changeover point.
b. If changeover is too low, turn off supply pressure and rotate changeover
adjustment screw counterclockwise. One turn increases changeover point by
about 3 psi (20 kPa). Turn on supply pressure and recheck to verify new
changeover point.
