Honeywell VRN Dynamic Pressure-Regulating Control Valves and Actuators Installation Instructions
38-00005EFS-04
VRN Dynamic Pressure-Regulating Control Valves and Actuators
INSTALLATION INSTRUCTIONS
Oversized valves can cause excessive cycling and the seat
and ball can be damaged because of the restricted
opening.
Proper Use
VRN valves are intended for use in chilled water and hot
water closed loop applications only, with a temperature
range of 35 to 250°F, and pressures up to 360psig.
Water should be properly filtered, treated and conditioned
for good operating performance, and according to
recommendations of the boiler or chiller manufacturers.
The installation of strainers and filters is recommended.
Do not use with manual balancing valves.
IMPORTANT
The presence of excessive iron oxide (red rust) in
the system voids the valve warranty.
APPLICATION
The VRN2 two-way dynamic pressure-regulating control
valves maintain constant flow of hot or chilled water with
glycol solutions up to 50% in closed-loop heating,
ventilating, and air conditioning systems, within the
specified pressure drop ranges of each model number.
These valve assemblies can be ordered with or without
factory-mounted actuators.
Application Notes
Valve sizing is important for correct system operation.
Undersized valves do not have sufficient capacity at
maximum load. Oversized valves do not have sufficient
authority over the load in modulating applications.
Effective Flow Rate
The built-in differential pressure regulator makes fluid
flow through the valve independent of changes in supply.
The pressure regulator virtually eliminates cavitation in
the valve, and decouples the control valve from the effects
of piping components such as reducers and elbows.
Pressure independent control valves are sized to match
design coil flow regardless of coil connection size. VRN2
valves eliminate the need to balance the system for proper
flow, and allow chillers to be operated at design
temperature differential for maximum efficiency at every
load condition. When used in a system with variable speed
pump drives, 3-way valves and coil bypass lines are not
required.
Required Operating Torque
Both Honeywell fail in place and fail-safe low torque direct
coupled actuators can be used with the VRN valves.
VRN valves use a patented seat design that reduces the
torque needed from the actuator.
Actuators with 27 lb-in torque, (for valves up to 1-1/4 in
size), and 35 lb-in torque (for 1-1/2 in size and above)
provide sufficient torque to operate the valve at rated
close-off. (See Table 1).
Maximum safe operating torque is 44 lb-in.
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
CAUTION
M34979A
FLOW FLOW
CLOSED
OPEN
NOTES: TO MOUNT ACTUATOR ON OPEN VALVE, TURN ACTUATOR FULLY
COUNTER CLOCKWISE AS SHOWN. TO MOUNT ACTUATOR ON
CLOSED VALVE, TURN ACTUATOR FULLY CLOCKWISE AS SHOWN.
The valves are tapped in NPT and should be sealed with an
Table 1. Close-off, Differential Pressure Ratings.
Close-off
Pressure Rating
Valve Type Valve Size
2 way 1/2 in. to 3 in. 100
(psi)
INSTALLATION
When installing this product...
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous condition.
2. Check ratings given in instructions and on the prod-
uct to ensure the product is suitable for your application.
3. Installer must be a trained, experienced service
technician.
4. After installation is complete, check out product
operation as provided in these instructions.
approved pipe sealant. Torque should not exceed 75 lb-ft.
Refer to actuator literature for actuator dimensions.
1. Clean the lines upstream of particles larger than
1/16 in. diameter (welding slag, pipe scale and other
contaminants).
2. Proceed with installation once the system specifics
(expansion/contraction of the system and its
medium as well as operating pressures) are within
tolerances.
3. Eliminate air from system.
4. Valves are marked to show flow direction.
IMPORTANT
Flow arrows must point in the direction of the flow
for proper operation.
5. Stem rotation:
a. Clockwise to close.
b. Counterclockwise to open.
NOTE: After valves have been installed in the pip-
Preparation
Equipment Damage Hazard
Foreign particles like dirt and metal chips can
damage the ball seals.
For trouble-free operation of the product, good
installation practice must include initial system
flushing, and chemical water treatment. Clean the
lines upstream of particles larger than 1/16 inch
diameter (welding slag, pipe scale, sand and other
suspended particulate). Use of a 50 micron (or
finer) system side stream filter is suggested.
Remove all filters before flushing.
Do not use boiler additives, solder flux and wetted
materials which are petroleum based or contain
mineral oil, hydrocarbons, or ethylene glycol
acetate. Compounds which can be used, with
minimum 50% water dilution, are diethylene
glycol, ethylene glycol, and propylene glycol
(antifreeze solutions).
If installing these valves in an addition to, or
retrofitting an existing building, do not assume
that the fluid in the existing piping meets these
criteria.
6. Valve must be mounted with the actuator/bracket
above the valve body. Do not install the valve with
the stem below horizontal or upside down. (See
Fig. 3 and 4.)
ing, the installer can determine the ball orientation within the valve from the notches
in the top of the valve stem. For VRN valves,
the lengthwise direction of the notch indicates the flow through the ball (i.e. when the
notch is parallel to the axis of the valve
between A and B ports, the ball will allow
flow through the valve).
Mechanical Installation
IMPORTANT:
38-00005EFS—04 2
Hold valve with pipe wrench by hexagonal fitting
ONLY. Do NOT handle the valve body with the pipe
wrench; product damage may result.
Fig. 1. Orientation of valve.
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
M13738A
VALVE BODY
VALVE STEMCOUPLER
WING NUT**
MOUNTING
PLATE**
ANTI-ROTATION
BRACKET**
BOLT**
STEM ASSEMBLY COVER**
SCREWS (2)**
HANDLE (REMOVABLE) FOR
MANUALLY ROTATING SHAFT**
STEM ASSEMBLY**
**INCLUDED IN REPLACEMENT KIT (PART NO. 5112-11)
SCREWS (2)**
M34954
45
45
M33091
Fig. 4. Acceptable valve angle from vertical
Mounting Plate Adjustment
The Actuator Mounting Plate can be rotated to a different
position for installation in confined spaces. This is
accomplished as follows:
1. Remove the handle from the shaft and set it aside.
2. Remove the two screws that hold the stem assembly
to the mounting plate and set them aside.
3. Remove and set aside the stem assembly.
4. Remove and set aside the two screws that attach the
mounting plate to the valve.
5. Remove and set aside hold-down ring from mount-
ing plate.
6. Rotate mounting plate around valve top to the
desired position.
Fig. 2. Valve assembly exploded view.
Fig. 3. Vertical valve installation.
NOTE: Take note of the screw hole positions on the valve.
They limit the mounting plate positions.
7. Lower ring down to valve body and engage it in the
new position relative to the mounting plate.
8. Tighten screws to valve body securing the mounting
plate.
9. Reattach the stem assembly to the mounting plate.
10. If desired, replace the handle on the shaft.
NOTE: See Fig. 2 for valve exploded view.
Electrical Installation
1. If necessary, remove actuator wiring cover.
2. Wire actuator using Figures 5 through 28 for the
application required.
3. Replace cover.
3 38-00005EFS—04
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
4
3
2
FLOATING ACTUATOR
24 VAC
Direct
Reverse
Service/Off
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
FLOATING
CONTROLLER
M18946A
24 VAC
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
PROPORTIONAL
CONTROLLER
+
–
FEEDBACK
1
325
PROPORTIONAL ACTUATOR
FEEDBACK
+
0(2)-10 VDC OF 0(4)-20 mA CONTROL SIGNAL ACCEPTABLE.
SET CONTROL SIGNAL DIP SWITCH TO “OFF” FOR VOLTAGE.
SET TO “ON” FOR CURRENT.
2
2
2 -10 Vdc
2 -10 Vdc
0 -10 Vdc
0 -10 Vdc
M18947B
4
5°
85°
S1 S2
S3 S5 S6
M25214A
END SWITCHES (CLASS II-ONLY)
Wiring
FLOATING ACTUATOR
DIRECT
SERVICE/OFF
REVERSE
432
1
3
24 VAC
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
2
CONNECTION REQUIRED FOR SPST CONTROL.
CONTROLLER
Fig. 5. MN6105 with On/Off SPDT Control.
2
M34869A
Fig. 7. MN7505 with 0(2)-10 Vdc Control.
Fig. 6. MN6105 with Floating Control.
38-00005EFS—04 4
Fig. 8. Wiring for MN6105 and MN7505 models with
aux./end switches.
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
FLOATING ACTUATOR
24 VAC
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
FLOATING
CONTROLLER
M33137D
2
3
4
1
BLACK
WHITE
BROWN
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
FLOATING ACTUATOR
24 VAC
1
FLOATING
CONTROLLER
2
3
4
1
M33138C
BLACK
WHITE
BROWN
2
M33557C
FLOATING ACTUATOR
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
2
3
4
1
24 VAC
BLACK
BROWN
WHITE
SPST
PROPORTIONAL ACTUATOR
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
4-20mA
CONTROLLER
M33141C
1
2
3
+
+
–
DIP SWITCH POSITION
1 2 MODE
OFF OFF 2-10V
OFF ON 0-10V
ON OFF 10-2V
ON ON 10-0V
PROPORTIONAL/MODULATING: 4-20mA CONTROLLER OUTPUT WITH
500Ω SERIES RESISTOR
TO OTHER
ACTUATORS
500 OHMS,
1/2 W
MINIMUM
24 VAC
RED
BLACK
WHITE
1
PROPORTIONAL ACTUATOR
24 VAC
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
0 (2)-10 VDC
CONTROLLER
M33140A
1
2
3
+
+
–
DIP SWITCH POSITION
1 2 MODE
OFF OFF 2-10V
OFF ON 0-10V
ON OFF 10-2V
ON ON 10-0V
PROPORTIONAL/MODULATING: 0(2)...10 VDC OR 10...0(2) VDC CONTROLLER OUTPUT
2
RED
BLACK
WHITE
2
1
Fig. 9. MVN613 with Floating Control.
Fig. 10. MVN613 or MVN643 with Two Position SPDT
Control.
Fig. 11. MVN643 with Two Position SPST Control.
Fig. 12. MVN713 with 4-20mA Control.
Fig. 13. MVN713 with 0(2)-10 Vdc Control.
5 38-00005EFS—04
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
SPDT
24 VAC
1
1
2
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
SET SWITCH TO FLOATING.
M37304
ACTUATOR
V
0°-90°/MODULATING
90°-0°/FEEDBACK
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
FLOATING, FWD
FLOATING, REV
2
RED
BLACK
BROWN
WHITE
CLASS 2
24 VAC
1
1
2
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
SET SWITCH TO FLOATING.
M37319
ACTUATOR
V
4
3
1
2
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
FLOATING, FWD
FLOATING, REV
2
0°-90°/MODULATING
90°-0°/FEEDBACK
RED
BLACK
BROWN
WHITE
CLASS 2
ACTUATOR
4 TO 20 mA
PROPORTIONING
CONTROLLER
24 VAC
1
1
2
3
2
490 TO 510
OHMS,
1/2 W
MINIMUM
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
SET SWITCH TO MODULATING IF AVAILABLE.
V
–
+
FEEDBACK
4
3
1
2
M37321
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
FLOATING, FWD
FLOATING, REV
3
0°-90°/MODULATING
90°-0°/FEEDBACK
RED
BLACK
BROWN
WHITE
CLASS 2
ACTUATOR
0/2 TO 10 VDC
PROPORTIONING
CONTROLLER
24 VAC
1
1
2
3
2
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION
AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
SET SWITCH TO MODULATING
IF AVAILABLE.
V
–
+
FEEDBACK
4
3
1
2
M37322
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
FLOATING
, FWD
FLOATING
, REV
3
ACTUATOR
V
4
3
1
2
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
FLOATING
, FWD
FLOATING
, REV
3
0°-90°/MODULATING
90°-0°/FEEDBACK
RED
BLACK
BROWN
WHITE
0°-90°/MODULATING
90°-0°/FEEDBACK
RED
BLACK
BROWN
WHITE
CLASS 2
Fig. 14. MS7505 with Two Position SPDT Control.
Fig. 17. MS7103 with 4-20 mA Control (MS7503 shown,
ignore selection switch).
Fig. 15. MS7505 with Floating Control.
CLASS 2
1
0/2 TO 10 VDC
PROPORTIONING
CONTROLLER
FEEDBACK
1
LINE VOLTAGE POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
2
3
SET SWITCH TO MODULATING IF AVAILABLE.
Fig. 16. MS7103 with 2-10 Vdc Control (MS7503 shown,
38-00005EFS—04 6
RED
24 VAC
–
+
2
1
2
BLACK
3
WHITE
4
BROWN
3
ignore selection switch).
ACTUATOR
0°-90°/MODULATING
90°-0°/FEEDBACK
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
FLOATING
FLOATING
V
, FWD
, REV
M37320
Fig. 18. MS7103 with 2-10 Vdc Control using two
actuators (MS7503 shown, ignore selection switch).
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
ACTUATOR
SPST
24 VAC
1
1
2
2
LINE VOLTAGE POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
V
1
2
M34973
3
ACTUATOR
SPST
1
1 LINE VOLTAGE POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
V
1
2
M34974
2
ACTUATOR
0/2 TO 10 VDC
PROPORTIONING
CONTROLLER
24 VAC
1
1
2
3
2
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
SET SWITCH TO MODULATING.
V
OR +
OR N/A
FEEDBACK
–
+
FEEDBACK
5
4
3
1
2
M19576A
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
Fltg, fwd
Fltg, rev
3
SPDT
ACTUATOR
0/2 TO 10 VDC
PROPORTIONING
CONTROLLER
24 VAC
1
1
2
3
2
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
SET SWITCH TO MODULATING.
V
OR +
OR N/A
FEEDBACK
–
+
FEEDBACK
5
4
3
1
2
M19577A
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
Fltg, fwd
Fltg, rev
3
SPST
ACTUATOR
0/2 TO 10 VDC
PROPORTIONING
CONTROLLER
24 VAC
1
1
2
3
2
LINE VOLTAGE POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
SET SWITCH TO MODULATING.
V
OR +
OR N/A
FEEDBACK
–
+
FEEDBACK
5
4
3
1
2
M34976
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
Fltg, fwd
Fltg, rev
3
RED
BLACK
ACTUATOR
SPST SWITCHES
MAIN
CABLE
WHITE
BROWN
+ OR 0˚−90˚
FEEDBACK OR 90˚−0˚
BLUE
BROWN
GRAY
SWITCHES
CABLE
BLACK
M37303A
Fig. 19. Wiring for MS7103 and MS3103 Auxiliary
Switches. Gray/Black = Normally Open. Closed in range
80 degrees to Fully Open. Blue/Brown = Normally
Closed. Open in range 10 degrees to Fully Open.
Fig. 22. MS7505 with override to full open.
Fig. 20. MS8105 with Two Position SPDT Control.
1
1
2
3
24 VAC
2
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
SET SWITCH TO FLOATING.
Fig. 21. MS7505 with Floating Control.
1
2
3
4
5
3
ACTUATOR
V
OR +
OR N/A
FEEDBACK
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
Fltg, fwd
Fltg, rev
Fig. 23. MS7505 with override to full closed.
M34975
Fig. 24. MS7505 with 0(2)-10 Vdc Controllers.
7 38-00005EFS—04
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
ACTUATOR
4 TO 20 mA
PROPORTIONING
CONTROLLER
24 VAC
1
1
2
3
2
490 TO 510
OHMS,
1/2 W
MINIMUM
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
SET SWITCH TO MODULATING.
V
OR +
OR N/A
FEEDBACK
–
+
FEEDBACK
5
4
3
1
2
M34977
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
Fltg, fwd
Fltg, rev
3
S1S3
S2
M35813
1
2
3
HOT
COM
CONTROLLER
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS
AND OVERLOAD
PROTECTION AS REQUIRED.
24 VDC SUPPLY ACCEPTABLE.
ADDRESS SELECTOR
S-BUS
S-BUS
24 VAC
CLASS 2
S-BUS
S-BUS
RED
BLACK
BROWN
BROWN
ACTUATOR
ADDRESS 11
ADDRESS 12
ADDRESS 13
ADDRESS 14
ADDRESS 15
TEST
Fig. 25. MS7505 with 4-20mA Controllers.
1
1 LINE VOLTAGE POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
SPST
1
2
ACTUATOR
V
M29122
24 VAC
24 VAC
ACTUATOR
2
2
1
2
3
4
5
3
1
2
3
4
5
3
V
OR +
OR N/A
FEEDBACK
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
Fltg, fwd
Fltg, rev
ACTUATOR
V
OR +
OR N/A
FEEDBACK
2-10 VDC
10-2 VDC
0-10 VDC
10-0 VDC
Fltg, fwd
Fltg, rev
M34978
1
1
0/2 TO 10 VDC
PROPORTIONING
CONTROLLER
1
LINE VOLTAGE POWER SUPPLY.
PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
2
24 VDC SUPPLY ACCEPTABLE.
SET SWITCH TO MODULATING.
3
24 VAC
HOT
COM
–
+
1
Fig. 28. MS7505 with 0(2)-10 Vdc controller operating
multiple actuators.
Fig. 26. MS4105 with 120 Vac Two Position SPDT
Fig. 27. Wiring for MS4105, MS7505, and MS8105
models with aux./end switches.
38-00005EFS—04 8
control.
Fig. 29. MS3103 with Sylk Bus control.
OPERATION AND CHECKOUT
Once both the mechanical and electrical installations are
complete:
1. Cycle the actuator to verify that the direction of rota-
tion suits the control sequence.
2. If the rotation direction is incorrect:
a. For 2-position and Sylk-enabled spring return
actuators: Remove, flip over, and replace actuator on the bracket.
b. For floating control actuators: Reverse two con-
trol signal wires (CW/CCW), or change position
of selector switch.
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
M27714
A
0
FLOW
RATE
(GPM)
DIFFERENTIAL PRESSURE (PSID)
12
10
6
4
5.8
8
16
22
28
50
M29707A
8
12
34 40
60
100% OPEN
80% OPEN
60% OPEN
40% OPEN
20% OPEN
c. For analog control actuators either:
(1) Change setting of reverse/direct-acting
switch, or
(2) To change spring return direction: remove,
flip over, and replace actuator on bracket.
3. If the control scheme requires fail-safe operation,
ensure that, upon removal of power, the fail position
coincides with the control sequence.
4. Spring return actuators are factory-configured for
normally-closed, fail-safe operation on power loss.
To change this action to normally-open, remove and
reinstall the actuator in the opposite orientation as
follows:
a. Loosen the shaft coupling bolt using a 10 mm
wrench.
b. Loosen all other mounting bolts connecting the
actuator to the mounting bracket, and set aside.
c. Remove the actuator from the valve shaft.
d. Move the Self-Centering Shaft Adaptor to the
opposite side of the actuator, as displayed in
Fig. 30.
M29908
Fig. 31. VRN2 cross section showing fitting, control ball,
and pressure regulator.
At full flow in a 2-position control application, a VRN2
behaves as a flow limiter.
The pressure regulator takes a minimum pressure to
operate, and has a maximum differential regulation
capability. See Fig. 32. The high pressure drop across a
VRN2 Valve is comparable to the pressure drop across a
control valve and balancing valve in a conventional
system design.
Fig. 30. Change actuator to normally open.
(1) Remove the retainer clip from the Self-Cen-
tering Shaft Adapter and set it aside for later
use.
(2) Remove SCSA from actuator.
(3) Reinstall SCSA on the opposite side of the
actuator, aligning it based on the stroke label-
ing.
(4) Replace the retainer clip on the shaft cou-
pling using the groove of the coupling.
e. Reconnect the actuator to the valve mounting
bracket by replacing the screws previously
Fig. 32. Pressure regulation, large body models.
removed (step b).
f. Tighten the shaft coupling bolt using a 10 mm
wrench or socket using maximum 120 lb-in
torque.
Operation
PIN changes constantly in a multi-zone system as other
valves open and close, changing system flow and head
pressure according to the characteristics of the supply
pump curve. Reaction of the mechanical pressure
regulator is instantaneous, eliminating changes in room
temperature due to changes in fluid flow, and reducing the
need for the control system to constantly operate the
control portion of the valve to correct for the non-load
related temperature changes that occur in a system with
standard control valves.
SETTINGS AND ADJUSTMENTS
At the full open position, VRN2 valves will maintain flow in
the loop. Flow rates are listed in the Specification Data
form 62-3115EFS. Under steady state operation, the
control system will only require the valve to open enough
to satisfy load conditions. During morning recovery from
night setback, the controller will usually command the
valve to 100%. For optimum performance, choose only the
next larger valve size needed to satisfy design load. Do not
oversize valves—reduced rangeability and may result in
less accurate temperature control.
9 38-00005EFS—04
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
CAUTION
0%
20%
40%
60%
80%
100%
0° 30° 60° 90°
VALVE STEM STROKE
FLOW
M29551A
10°
20°
40° 50°
70°
80°
FULL PORT
BALL
2-WAY
CHARACTERIZED
FLOW
STEM
ASSEMBLY
COUNTERSUNK
SCREWS
STEM RETAINER
PLATE
“T” SYMBOL
STEM
UPPER PACKING
GLAND
O-RING
LOWER PACKING
GLAND
M34994
Ball valves close between 10 and 15% of stroke, to ensure
full seal engagement. If desired, modulating actuators can
be set to 0-10 V response so that 2 V of a 2-10 V control
signal more closely corresponds to minimum flow. The
valve will still close with signal loss.
If desired, maximum flow may be trimmed to a lesser value
in one of two ways:
1. With modulating actuator, limit span of control volt-
age issued by the building automation controller.
Valves with flow control inserts have an equal percentage flow characteristic (See Fig. 33). Each 10%
reduction in maximum control voltage will result in a
10% reduction in flow.
Service and Repair
The valve stem can be replaced in-line, if necessary. See
Fig. 34.
Fig. 34. Replacing the valve stem in-line.
Follow steps 1 to 6 of “Mounting Plate Adjustment” on
page 3, then:
1. If the lower packing gland is stuck, remove it with
gland removal tool or rubber-tipped dental tool.
Fig. 33. Typical flow characteristics.
2. To mechanically limit stroke, set DCA to full open
position. Loosen shaft coupling and rotate valve
shaft to desired maximum flow position, as confirmed by pressure measurement across coil, using
coil manufacturer's data. Retighten shaft coupling.
Use Fig. 33 as a guide to setting actuator stroke.
If using mechanical adjustment technique with
MN/MS7505 modulating actuators, the stroke autoadaption feature will automatically scale the 2–
10 Vdc signal to the mechanical rotation of the ball.
See actuator literature for details.
Coil flow can be confirmed by reading pressures at the coil
inlet and coil outlet (not across control valve as with
conventional balancing—this pressure drop will be
constant), and using the manufacturer's data to calculate
flow.
Note that the pressure regulator in this valve guarantees
that the flow through the coil will not be affected by
upstream changes in pressure. Unlike conventional
balancing valves, it is not necessary to reconfirm coil flow
after adjusting other valves. Any overflow during morning
recovery due to oversized pressure regulated valves will
not affect other valves in the system, provided pumps are
capable of required flow.
Avoid scratching the inside of the valve neck.
This may cause a leak when re-assembled.
2. Carefully remove any fouling or corrosion from
inside of valve.
3. Align arrow with short leg of “T” symbol on new stem
assembly.
NOTE: “T” symbol will vary.
4. Insert the new stem assembly. Be sure to line up the
stem key with the ball slot.
5. Fasten stem retainer high pressure plate to the valve
using the new countersunk screws. Then fasten the
mounting plate to the valve.
6. Repressurize valve and confirm stem does not leak
before proceeding.
7. Slide the sub shaft over the stem with the tab ori-
ented as shown in Fig. 34.
8. Replace the thermal break, shaft, and shaft cover. If
shaft has come loose from thermal break, push
firmly on end of shaft until blade in shaft snaps into
thermal break.
9. Replace actuator and secure it to shaft and mount-
ing plate.
10. Snap handle onto top of shaft.
Any other service to valve such as seat seal replacement
requires removal of valve from piping.
38-00005EFS—04 10
VRN DYNAMIC PRESSURE-REGULATING CONTROL VALVES AND ACTUATORS
11 38-00005EFS—04
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