Calibration Check - Honeywell RP908A Series Service Data

CALIBRATION CHECK

RP908A
Change the setpoint of the Controller to the existing
sensor temperature if the two do not already match. The
branchline pressure should be at its calibration pressure
of 8 + 1 psi (55 -t- 7 kPa) unless otherwise noted on job
drawings. If recalibration is necessary, see CALIBRA-
TION,
RP908B
Determine the existing calibration temperature from
the reset schedule on the job drawings. Draw a straight
line on graph as shown in Figure 4. Measure the tempera-
ture at the Port 2 sensor. Find corresponding Port 1 sen-
sor temperature (Fig. 5). Measure temperature at Port 1
sensor location. This temperature must agree within two
OUTDOOR AIR TEMPERATURE IN F(C)
Fig. 4, Typical Discharge Air Reset Schedule.
21c
w 150
I
OUTDOOR AIR TEMPERATURE IN F (C)
Fig. 5. Typical Hot Water Reset Schedule for
Radiation Systems.
20884
40 30
20885
percent of the sensor range span and the branchline pres-
sure must be within the operating range of the controlled
device. If recalibration is necessary, see CALIBRA-
TION.
CHANGE FROM DIRECT TO REVERSE
ACTING
The change from direct to reverse acting is made by
following the three steps listed in Figure 6.
P I V O T
SCREWS (2)
LESS THAN 15 PERCENT, REGARDLESS OF ACTION.
Fig, 6. Set-Up for Reverse-Acting Operation.
ADJUSTMENTS
PROPORTIONAL BAND
If the original setting shown on the job drawings must
be changed:
1. Loosen the Proportional Band Adjustment Knob
(Fig. 7) and slide the Proportional Band Indicator
to the desired setting.
NOTE: When a proportional band of more than
I5 percent is used, fasten the Bias Spring
to the Lever Assembly (Fig. 6). This spring
is left unconnected if proportional band is
15 percent or less.
2. The Controller must be recalib
proportional band is changed.
3. CbNNECT RA SPRINGS (2)
TO NOTCHES (2)
4707-l
ra .ted whenever the
75-553 1