Data Sheet for Product

TH 192 DN Day-Night and DNV Day-Night-Vent Room Thermostat Technical Instructions
Document Number 155-067P25
February 11, 2022
Siemens Industry, Inc. Page 11
Troubleshooting
Before troubleshooting the thermostat per Table 5, ensure that there is clean, dry supply
air at 18 psi (124 kPa) for day control, and 25 psi (172 kPa) for night. Use the test probe
gauge and needle adapter to measure the control pressure at the thermostat test port.
The output pressure test port is accessible without removing the thermostat cover
through the 8th opening from the top left side.
Figure 10. Accessing Output Pressure Test Port.
Table 4. Troubleshooting Guide.
Problem
Check
Cause
Action
Control pressure
stays at
approximately zero
Air supply
Low supply pressure
As required
Nozzle or flapper
Dirt on nozzle or
flapper
Clean nozzle or
replace thermostat
Restrictor
Clogged restrictor
Replace restrictor
Calibration
Out of calibration
Recalibrate
Control pressure
stays at
approximately
supply pressure
Nozzle
Clogged nozzle
Clean nozzle or
replace thermostat
Calibration
Dirt on either supply or
exhaust valve seat
Alternately close and
open nozzle by gently
pushing down the
bimetal
Excessive air
leakage from
exhaust port on left
side of thermostat
Supply and return
line connection
Connections are
interchanged or
connection to port is
incorrect
As required