VA7800 Series Electric Valve Actuators Product Bulletin
2
Application Overview
VA7810-Axx-2 Series Non-Spring Return On/
Off and Floating Point Actuator
The VA7810-AGx-2 Series Non-Spring Return
Actuators provide fail-in-place on/off or modulating
control of valves in HVAC systems. On/Off Control is
provided from a manual switch, an auxiliary switch from
a pump contactor, or a similar device. Floating Point
Control is provided from a triac or relay.
VA7810-HGx-2 Series Non-Spring Return
Proportional Actuator
The VA7810-HGx-2 Series Non-Spring Return
Actuators offer fail-in-place proportional control of
valves in HVAC systems regulated by an electronic
controller. These actuators are configured for response
to 0 to 10 VDC, 2 to 10 VDC, 0 to 20 mA, or 4 to 20 mA.
The VA7810-HGx-2 Series can also be custom
configured for valve sequencing. The minimum setpoint
is 0 to 6 VDC (0 to 12 mA), and maximum input signal
is 3 to 10 VDC (6 to 20 mA). A
0 to 10 VDC, or 2 to 10 VDC feedback signal is
available for position indication. The actuator features a
preset actuator position with a stem that extends or
retracts on loss of signal. However, when you select
current input, this stem feature is not available.
VA7820-HGx-2/VA7830-HGx-2 Series Spring
Return Proportional Actuator
The VA7820-HGx-2 and VA7830-HGx-2 Series
Actuators are Spring Return actuators that provide
fail-safe proportional control of valves in HVAC systems
regulated by an electronic controller. In the event of
power loss, the VA7820-HGx-2 Series Actuators spring
return with the actuator stem fully retracted and the
valve stem in the full up position. On loss of power, the
VA7830-HGx-2 Series Actuators spring return with the
actuator stem fully extended and the valve stem in the
full down position.
These actuators are configured for response to 0 to
10 VDC, 2 to 10 VDC, 0 to 20 mA, or 4 to 20 mA. Both
models of actuators can also be custom configured for
valve sequencing. Minimum setpoint is 0 to 6 VDC (0 to
12 mA) and maximum input signal is 3 to 10 VDC (6 to
20 mA). A 0 to 10, or 2 to 10 VDC feedback signal is
available for position indication. The actuators feature a
preset actuator position with a stem that extends or
retracts, on loss of signal. When current input is
selected, this stem feature is not available.
Operation
The VA7800 Series of actuators offers up to 1 in.
(25 mm) of linear stroke for the operation of
Johnson Controls® VG7000 Series Bronze Control
Valves. The actuators interface to all threaded stem
VG7000 Valves
and can be used on all stainless steel
trim VG7000 series valves from 1/2 in. to 2 in. The
actuator should not be used on brass trim VG7000
series valves from 1/2 in. to 3/4 in.
All actuators can
be manually positioned by means of a 5 mm Allen
wrench.
For non-spring return actuators, engage manual
operation by inserting the Allen wrench into the
hexagonal socket and pushing down to cut off the
power to the motor. Turn the Allen wrench clockwise to
extend the actuator stem; turn the wrench
counterclockwise to retract the actuator stem.
For spring return actuators, manual operation requires
that the power be disconnected. On loss of power, the
actuator spring force moves the stem to its fail-safe
position. For manual operation, insert the Allen wrench
into the hexagonal socket and turn the wrench either
clockwise or counterclockwise depending on the
actuator model. When you reach the desired stem
position, push the wrench down and slightly rotate the
wrench in the opposite direction to lock it in position.
When power resumes, the actuator is released from its
manual position.
Note:
After using manual control to position the
actuator, it is recommended that a self-calibration cycle
be performed to assure proper operation.
VA7810-AGx-2 Series Non-Spring Return On/
Off and Floating Point Actuator
The VA7810-AGx-2 Series Non-Spring Return
Actuators are offered with On/Off Control or Floating
Control. Select these controls by applying power to
different terminals located on the actuator. For a more
detailed procedure, refer to the appropriate installation
instructions for the actuator.
IMPORTANT:
The VA7800 Series Electric Valve
Actuators are intended to control saturated steam,
hot water, and chilled water flow under normal
equipment operating conditions. Where failure or
malfunction of the VA7800 Series Valve Actuator
could lead to personal injury or property damage to
the controlled equipment or other property,
additional precautions must be designed into the
control system. Incorporate and maintain other
devices, such as supervisory or alarm systems or
safety or limit controls, intended to warn of or protect
against failure or malfunction of the VA7800 Series
Valve Actuator.