Johnson Controls Penn P70 Series Product/Technical Bulletin page 8

Convertible High Pressure Reset
Mechanism on P70S and P170S Controls
The P70S and P170S type dual pressure controls are
equipped with a convertible high side pressure reset.
The control may be configured to automatically reset
after CUT OUT (when the pressure drops to CUT OUT
minus differential), or to manually reset after CUT OUT
(by pressing down the reset lever).
To change the Convertible High Pressure Reset
operation:
1. Disconnect all power sources to the pressure
control and remove the control cover.
2. For Manual Reset Operation: Loosen the lock
nut, unscrew the stop screw (counterclockwise)
being careful to not remove the screw completely
from the bracket. (See Figure 11.)
For Automatic Reset Operation: Loosen the lock
nut, push the reset lever down, and screw in the
stop screw (clockwise) fully. (See Figure 11.)
3. Tighten the lock nut to hold the stop screw in
place, and replace the control cover.
4. Restore all power sources and cycle the
equipment to check control operation.
Reset Lever in Locked-Out
Manual Reset Position
Stop Screw
Lock
Bracket
Nut
Stop Screw Positioned for
Manual Reset Lockout
Operation
Figure 11: Setting the Convertible High Pressure
Reset Mechanism (P70S or P170S Controls)
Low Pressure Limited Knob Adjustment
Some dual pressure controls are supplied with a
Limited Knob Adjustment kit for the low pressure side
of the control, which restricts the adjustment of the low
side range and differential screws, and helps deter
overadjustment or tampering. A stop on the bottom of
the knob limits adjustment to less than one turn.
8 P—P70, P72, and P170 Controls for Dual Pressure Applications Product/Technical Bulletin
Reset Lever in Normal
Operation position
Stop Screw
Lock
Bracket
Nut
Stop Screw Positioned for
Automatic Reset
Operation
The Limited Knob Adjustment may be installed at the
factory or included as a separate kit, depending on the
model ordered. To install the Limited Knob Adjustment
kit refer to the following guidelines and steps.
To lock the differential screw and allow limited
adjustment of the range screw, install the knob on the
range screw. This configuration allows limited
adjustment of the low event and high event setpoints,
without changing the differential.
To lock the range screw and allow limited adjustment
of the differential screw, install the knob on the
differential screw. This configuration allows limited
adjustment of the low event setpoint (on All-Range
controls) or differential setting (on MICRO-SET
controls), without changing the high event setpoint.
Note: The Limited Knob Adjustment kit for the
All-Range controls can not be used with the
MICRO-SET controls (and vice-versa).
To install the Limited Knob Adjustment kit:
1. Adjust control pointers to desired high event and
low event setpoints (on All-Range controls), or
differential setting (on MICRO-SET controls).
2. Place the spacer on the desired adjustment screw.
•
All-Range controls (with Limited Knob
Adjustment kits) have round and knurled
adjustment screws—the spacer must always
be placed on the range screw.
•
MICRO-SET controls have square adjustment
screws, always place the spacer on the same
adjustment screw as the knob.
3. Align the large end of the indicator plate over the
adjustment screw with spacer, and align the small
end of the indicator plate over the adjustment
screw to be locked, and attach the indicator plate.
4. Align the knob over the large end of the indicator
plate, attach the knob to the adjustment screw,
and tighten the setscrew.
Adjustment Knob with Set Screw
Range Screw
Differential Screw
Limited Knob Adjustment
installed to lock range screw,
and allow limited adjustment
of differential screw.
Figure 12: Limited Knob Adjustment Installation
Indicator Plate
Spacer
Range Screw
Limited Knob Adjustment
installed to lock differential
screw and allow limited
adjustment of range screw.