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Technical Instructions
Document Number 155-064P25
April 1, 2005
Operation,
continued
Calibration
General
Page 4
The thermostats are factory calibrated at 72° F (22° C) and 7-1/2 psi (52 kPa) control
pressure.
1. Determine the temperature at the remote bulb.
2. Set pointer to the temperature found. Dial increments are approximately five degrees on
the major divisions with one degree subdivisions, beginning at 60° F clockwise to 85° F.
3. Loosen (do not remove) the return line test port screw. Slip the rubber line over test port
and connect to test gauge (Figure 2).
Figure 2. Test Port and Gauge used for Calibration.
4. With the knob set at the temperature of the remote bulb, the output (return line)
pressure should be between 7 and 8 psi (48 and 55 kPa) for all models. If the output
pressure is not 7 to 8 psi (48 and 55 kPa), remove knob after loosening its set screw.
Then rotate the set point adjustment post until pressure is 7 to 8 psi.
5. Replace knob and set pointer to temperature of the bulb, lock, and then turn to desired
setting.
The thermostat is now in calibration.
Figure 1. Thermostat Operation.
TH 188 Unit Mounted Thermostat
Siemens Industry, Inc.
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