STP SERIES Install, Operation, and Maintenance Manual
SECTION 3: OPERATION AND CONTROLS
Rev-1
Diversified Heat Transfer, Inc.
•
439 Main Road, Route 202
•
Towaco, New Jersey 07082
Page
25
of
97
STP Manual
PHONE: 800-221-1522
•
WEBSITE: www.dhtnet.com
09/11/2019
FIGURE 3-7: Valve Characteristics - Equal Percentage (L) and Linear (R)
In the event of a power failure, or if the power is switched off, the spring force closes the valve
automatically (control path ports A → AB normally closed).
3.5.3.2 Manual Control
The valve control path (ports A → AB) can be opened mechanically up to 95% of the full stroke
by pressing the knob inward and turning it clockwise (to the MANUAL position). This disables
the control signal from the controller.
To disable automatic control of the valve, press the knob (Figure 3-6) inward and turn it
counterclockwise (to the OFF position). The valve will close.
For automatic control, the knob (Fig. 3-6) must be set to the AUTO position (knob will spring
out).
WARNING!
The valve knob (Figure 3-6 MUST be set to AUTO position for proper orientation of the STP
Series unit.
3.5.4 Controller Status LED Indication
Open the electronics module of the Controller Valve to view the two-color LED display, which
indicates the operating status of the valve. The table below identifies what the behavior and color
of the LEDs indicate.
3-WAY CONTROL VALVE STATUS LEDs
LED Display
Status
Description
Green LED
On continuously
Automatic mode: Auto (normal, no faults)
Flashing
– Mechanically set to MANUAL
– Mechanically set to OFF
– Currently in auto-calibration mode
Red LED
On continuously
– General fault
– General calibration fault
– Microcontroller fault
Flashing
– Faulty 24 VAC supply (or low power)
LED Off
– No 24 VAC supply
– Fault with electronics module
EQUAL PERCENTAGE
LINEAR
