STP SERIES Install, Operation, and Maintenance Manual
SECTION 4: MAINTENANCE
Rev-1
Diversified Heat Transfer, Inc.
•
439 Main Road, Route 202
•
Towaco, New Jersey 07082
Page
61
of
97
STP Manual
PHONE: 800-221-1522
•
WEBSITE: www.dhtnet.com
09/11/2019
4.5
BOILER WATER CONTROL VALVE OPTION MAINTENANCE
The manufacturer documentation included with the unit gives specifics for operation and
maintenance of the boiler water control valve option. The Submittal sheet and drawing included
with the unit will give the exact location, as well as interlocks with other components. This
information should be reviewed before removal/replacement of the temperature control valve.
4.5.1 Control Valve Maintenance
The valves and actuators require no maintenance or service. The valve stem is sealed with a
maintenance-free O-ring gland. Open the electronics module of the 3-Way Controller Valve to
view the two-color LED display, which indicates the operating status of the valve. See the table
below to determine if the valve may possibly be faulty.
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
Should the valve electronics prove faulty, the electronics module should be replaced with a new
one. Contact DHT for part numbers and ordering information. See the replacement information
below for mounting and installation.
4.5.2 Control Valve Replacement
Mounting and operating instructions are printed on the actuator and on the electronics module.
The valve is suitable for straight-through arrangement and the strict observance of the direction
of flow is essential.
To replace a faulty or effective unit, refer to the following instructions.
FIGURE 4-5: 3-Way Control Valve Component Locations
3-WAY CONTROL
VALVE
ELECTRONICS MODULE
HEAT
EXCHANGER