Data Sheet for Product

599 Series Zone Valve 2-way, 3-way Thermic Actuators Technical Instructions
Document Number 155-780
May 19, 2017
Siemens Industry, Inc. Page 3
CAUTION:
When selecting a heating or cooling on/off zone valve that must be closed for
long periods of time or an entire season, use a Normally Closed actuator (such
as the STA73U Actuator) for new or replacement applications.
If the valve needs to be open for extended periods of time or an entire season, use a
Normally Open actuator (such as the STP73U Actuator) for new or replacement
applications.
STP Actuators should not be used on hot water systems that remain
operational all year long or where actuators are continually commanded closed
during the summer
Mechanical Design,
Continued
Two-position Control
Position and Movement
Indication
STA73U
The actuator can be installed in any 24 Vac/Vdc control loop for two-position control or
pulse width modulation (PWM) control).
Figure 1. STA73U
Position and Movement Indication.
In this position the STA73U actuator is de-
energized. The actuator shaft is extended
and the valve is closed.
In this position the STA73U actuator is
connected to the power supply for at least
4-1/2 minutes. The actuator shaft is
retracted and the valve is open.
STP73U
Figure 2. STP73U
Position and Movement Indication.
In this position the STP73U actuator is de-
energized. The shaft is retracted and the
valve is opened.
In this position the STP73U actuator is
connected to the power supply for at least
4-1/2 minutes. The actuator shaft is
extended and the valve is closed.