Pneumatic Control Manual 717.1
Room Devices Section
Technical Bulletin T-4000
Issue Date 0984
© 1984 Johnson Controls, Inc.
1
Code No. LIT-7171089X
T-4000 Series Room Thermostat
Adjusting Instructions*
The T-4000 Series Pneumatic
Room Thermostats are factory
calibrated to the values specified
in Table 1. If these settings are
suitable to the application, no
adjustments need to be made. If
different settings are required,
turn the set point dial to the
desired value.
If the room temperature is out of
control, determine the cause of
the problem. Possible causes
not involving the thermostat are
listed below.
1. Check for proper operation
of the controlled device.
2. Check to see if the controlled
medium (water, for example)
is hot or cold enough to
maintain the desired
temperature.
3. Check for unusual or
extreme loads in the space
which may overcome the
efforts of the thermostat to
maintain control.
If it is determined that the
thermostat is out of adjustment,
follow the appropriate instructions
to recalibrate the instrument.
Sensitivity Adjustment
(See Fig. 1)
All T-4000 series thermostats
have an integral output pressure
test port. The newer high volume
output thermostats have a plug-in
test port fitting which accepts a
hypodermic needle test probe
and gage (X-200-140 and G-
2010-11). On older models, the
test port cap screw must be
removed to accept a screw-in
test gage (X-200-19). For these
units, a test port fitting (T-4000-
615) can be ordered. All low
volume output thermostats have
hypodermic needle test points.
For units that require a screw-in
gage, remember to replace the
test port cap screw after
adjustment.
The sensitivity of the T-4000
series instruments is factory set
at 2.5 PSI/F
°
(32 kPa/C
°
). It is
adjustable from 1 to 3 PSI/F
°
(13 to 38 kPa/C
°
) for low volume
output thermostats and from .
75 to 4 PSI/F
°
(10 to 51 kPa/C
°
)
for high volume output
thermostats. (Sensitivity of the T-
4003 is fixed at 2.5 PSI/F
°
).
1. Furnish the appropriate
supply pressure to the
instrument.
2. Insert the appropriate gage.
3. Note the output pressure.
Note:
The output pressure
for T-4054 thermostats must
be within one of the two
control ranges (not within the
deadband range).
4. For high volume output
thermostats, move the
sensitivity slider toward the
control port to increase or
away from the control port to
decrease the sensitivity. For
low volume output
thermostats, move the
sensitivity slider down to
*
This bulletin provides adequate instructions for making basic adjustments to
T-4000 series room thermostats. For more detailed information, contact the local
branch office.
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