T-4000 Technical Bulletin 3
T-4054 Deadband and Set
Point Adjustment
(See Fig. 2)
The T-4054 can easily be
adjusted to suit the application by
changing the settings on the
heating and cooling dials. If the
thermostat has been tampered
with or is out of adjustment,
proceed with the following
instructions to recalibrate the
instrument.
Note: On deadband applications
which have overlapping spring
ranges, it is suggested that a
C-9200 or other sequencing
device be used to bias the
cooling valve spring range to
compensate for spring range
shift.
Deadband Setting
If it is necessary to check or reset
the deadband setting, proceed as
follows:
Turn the lower set point dial to 85F
on direct acting models or 55F on
reverse acting models. Turn the
upper set point dial to 55F on direct
acting models or 85F on reverse
acting models. Insert a hypodermic
needle test probe into the test
connection. The reading on the test
gage is the actual deadband
pressure.
If it is necessary to adjust this
pressure to meet application
requirements, proceed as follows:
1.
Remove the T-4054 from the
mounting bracket and pull it
away from the wall so the
deadband adjusting screw
on the back of the instrument
is exposed (see Fig. 3).
2.
Turn the screw clockwise to
increase or counter-
clockwise to decrease the
deadband pressure until the
gage reads the desired
pressure. Approximately
one half turn will produce a
1 PSI (7 kPa) change in
deadband pressure.
3.
Return the set point dials to
the original settings.
Set Point Calibration
(See Fig. 2)
1.
Set the lower set point dial to
85F for direct or 55F for
reverse acting models.
2.
Note the ambient
temperature at the element.
3.
Set the upper dial to this
temperature (direct acting
model: heating, reverse
acting model: cooling).
4.
Turn the upper calibration
screw until the control
pressure is in the middle of
the spring range of the
controlled device (heating).
5.
Set the lower dial to the
temperature noted in step 2
(direct acting model:
cooling, reverse model:
heating).
6.
Turn the lower calibration
screw until the control
pressure is in the middle of
the spring range of the
controlled device (cooling).
7.
Turn the upper dial to the
desired set point.
Fig. 2: T-4054 Adjustments
T-4054 Operational Graph
Fig. 3: Back View of T-4054
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