Honeywell ML6174 Series User manual

PRODUCT DATA
® U.S. Registered Trademark
Copyright © 1997 Honeywell Inc. • All Rights Reserved 63-2534-1
ML6174
ML7174
ML6174, ML7174 Non-Spring Return
Direct Coupled Actuators
APPLICATION
The ML6174 and ML7174 are non-spring return direct
coupled actuators (DCA) used to control dampers in
applications such as variable air volume (VAV) terminal units.
Suitable for use with single pole double throw (spdt) floating
thermostats and electronic systems.
FEATURES
• Damper shaft direct mount.
• 70 lb-in. torque.
•45
°, 60°, and 90°selectable stroke in either clockwise
(cw) or counterclockwise (ccw) directions.
• 90-second timing models suitable for use with
pressure-independent VAV systems.
• Seven-minute timing models suitable for use with
pressure-dependent VAV systems.
• Magnetic coupling provides 130 lb-in. (or less) stall
torque, eliminating the need for mechanical stops or
limit switch adjustments.
• Two field-addable auxiliary switches.
• Auxiliary feedback potentiometer field-addable on
some models.
•0
°to 30°minimum position adjustment (cw or ccw
direction) on some models.
• Manual declutch on all models.
• W7620 Terminal Unit Controller compatibility.
• 2 to 10 Vdc or 4 to 20 mA control input for ML7174.
• Commercial Zone Damper in W7600 Commercial Zone
System compatibility.
• UL94-5V rated.
Contents
Application .......................................................................... 1
Features .............................................................................. 1
Specifications ...................................................................... 2
Ordering Information ........................................................... 2
Installation ........................................................................... 5
Operation ............................................................................ 9
Checkout ............................................................................. 11

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—1 2
ORDERING INFORMATION
When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the
TRADELINE® Catalog or price sheets for complete ordering number.
If you have additional questions, need further information, or would like to comment on our products or services, please write or
phone:
1. Your local Home and Building Control Sales Office (check white pages of your phone directory).
2. Home and Building Control Customer Logistics
Honeywell Inc., 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386 [phone]
In Canada—Honeywell Limited/Honeywell Limitée, 155 Gordon Baker Road, North York, Ontario M2H 3N7.
International Sales and Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France,
Germany, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.
SPECIFICATIONS
Models:
70 lb-in. torque with declutch, selectable 45°, 60°and 90°
stroke in both cw or ccw directions.
ML6174A: 90 second, 3 minute and 7 minute timing, spdt
Floating Series 60. Includes auxiliary potentiometer
drive for use with field-addable feedback potentiometer,
minimum position adjustment setscrews for cw or ccw
operation, and 4074ENJ Bag Assembly.
ML6174B: 90 second, 7 minute timing, spdt Floating
Series 60. Available with minimum position adjustment
setscrews. Includes 4074ENJ or 4074ENY Bag
Assembly.
ML6174C: 90 second, 3 minute and 7 minute timing, spdt
Floating Series 60. Includes auxiliary potentiometer
drive for use with field-addable feedback potentiometer,
minimum position adjustment setscrews for cw or ccw
operation, 4074ENJ Bag Assembly, and integral conduit
cover.
ML6174D: 90 second, 7 minute timing, spdt Floating
Series 60. Available with minimum position adjustment
setscrews. Includes 4074ENJ or 4074ENY Bag
Assembly, as appropriate, and integral conduit cover.
ML7174A: 90 second timing, 2 to 10 Vdc or 4 to 20 mA
control input. Includes 4074ENJ Bag Assembly.
Electrical Ratings:
Input Voltage: 24 Vac ±20%, 50/60 Hz.
Power Consumption (Maximum), at 24 Vac:
ML6174A,B: 2.3W, 0.1A, 2.4 VA.
ML7174A: 5.2W, 0.22A, 5.4 VA
Control Inputs:
100K ohm input impedance for voltage.
Outputs:
500 ohm and 2K ohm outputs for ML6174A,C.
Temperature Ratings:
Ambient: 20°to 125°F (-18°to 50°C).
Derated Timing to: -20°F (-29°C).
Shipping and Storage: -40°to 150°F (-40°to 66°C).
Humidity Ratings:
5% to 95% RH noncondensing.
Torque Ratings (ML6174 and ML7174):
Running: 70 lb-in. (8.0 N•m).
Breakaway: 70 lb-in. (8.0 N•m).
Stall: 70 lb-in. (8.0 N•m) minimum;
130 lb-in. (14.0 N•m) maximum.
Auxiliary Switch Ratings:
Electrical selective NO or NC, not simultaneous.
Pilot Duty:
50 VA, 24 Vac.
Switch Differential:
Three angular degrees maximum.
Dimensions:
See Fig. 1, 1A, and 1B.
Feedback Potentiometer Ratings (ML6174A,C):
Electrical Rating (200976A,C Potentiometer): 24 Vac,
50/60 Hz, 2.25W.
Resistance Output (Resistance Linear as Measured
Between Terminals R-B):
0 ohms (at 0°, cw stroke).
250 ohms (at 45°, cw stroke).
333 ohms (at 60°, cw stroke).
500 ohms (at 90°, cw stroke).
Actuator Timings (at 50 Hz Nominal):
90-second Models:
90°—108 sec.
60°—72 sec.
45°—54 sec.
Three-Minute Models:
90°—216 sec.
60°—144 sec.
45°—108 sec.
Seven-Minute Models:
90°—504 sec.
60°—336 sec.
45°—252 sec.
Actuator Timings (at 60 Hz Nominal):
90-second Models:
90°—90 sec.
60°—60 sec.
45°—45 sec.

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—13
Three-Minute Models:
90°—180 sec.
60°—120 sec.
45°—90 sec.
Seven-Minute Models:
90°—420 sec.
60°—276 sec.
45°—210 sec.
Damper Shaft Mounting:
Actuator can be mounted with shaft in any position.
Damper Shaft: 3/8 to 1/2 in. (10 to 13 mm) square or
round. Minimum Damper Shaft Length: 1-3/4 in. (45
mm).
Secured Using: Two 1/4 in. (6 mm) 28 NF Allen screws
(see Fig. 6).
Declutch Feature: Provided for ease of mounting.
Approvals:
Underwriter’s Laboratories Inc. Component Recognized:
File No. E4436; Guide No. XAPX2. Meets UL94-5V
plenum requirements.
Canadian Standards Association Certified (includes
auxiliary switch).
Noise Output:
45 dBA at 1 meter maximum.
Accessories:
200976A Auxiliary Potentiometer (0 to 500 ohm).
200976C Auxiliary Potentiometer (0 to 2000 ohm).
201052A Auxiliary Switch (one).
201052B Auxiliary Switch (two).
4074ENJ Bag Assembly—includes stop pin, shaft adapter,
and two minimum position screws.
4074ENY Bag Assembly—includes stop pin and shaft
adapter.
4074EVK Short Shaft Extender.
7640QW Metal Enclosure—for attaching conduit to
actuator.
T641 Floating Thermostat—for use with seven-minute
models.
T6984 Floating Thermostat—for use with 90-second and
seven-minute models.
T7984 Modulating Thermostat—for use with ML7174.
1
(25)
M10243
CW
COM
CCW
OPTIONAL
AUXILIARY
SWITCH
15/32
(12)
1/8
(3) 5/16 (8)
1-11/16 (43)
11/16
(18)
3-3/8 (86)
4-1/4
(108)
5/32
(9)
4-7/8
(123)
5-9/16
(141)
2-7/8 (73)
1-11/16 (42)
1/8
(3)
1-5/16
(33)
7/8
(22)
2-1/2 (64)
Fig. 1. Approximate dimensions of ML6174A,B DCA in in. (mm).

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—1 4
Fig. 1A. Approximate dimensions of ML6174C,D DCA in in. (mm).
M11621
60°
45°45°
60°
5-7/8
(149)
1-13/16
(46)
1
(25)
3-5/8 (92)
1-13/16 (46)
3 IN. (76 MM)
MINIMUM SPACING
REQUIRED
FOR REMOVING
CONDUIT COVER
3-3/4 (95)
7/8
(22)
1
(25)
M10244A
OPTIONAL
AUXILIARY
SWITCH
T1
T2
-
+
+
24 Vac
2-10 Vdc
4-20 mA
4-7/8
(123)
4-1/4
(108) 5-9/16
(141)
11/16
(18) 1/8
(3)
3-3/8 (86)
1/8 (3)
15/32
(12)
2-7/8 (73)
1-11/16 (42)
1/8
(3)
3 (76)
5/32
(9)
7/8
(22)
Fig. 1B. Approximate dimensions of ML7174 DCA in in. (mm).

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—15
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 the ratings given in the instructions and on the
product to make sure the product is suitable for your
application.
3. Installer must be a trained, experienced service
technician.
4. After the installation is complete, check out the product
operation as provided in these instructions.
WARNING
Explosion Hazard.
Can result in serious injury or death.
Install the actuator in areas free of escaping gas and
other explosive vapors to prevent a spark from
actuator or attached accessories from igniting
escaping gas or vapors.
CAUTION
Electrical Shock or Equipment Damage Hazard.
Disconnect power before installation.
Disconnect all power supplies before installation.
Motors with auxiliary switches can have more than
one disconnect.
CAUTION
Actuator Damage Hazard.
Deteriorating vapors and acid fumes can damage
the actuator metal parts.
Install actuator in areas free of acid fumes and other
deteriorating vapors.
Location
Choose a location for the actuator that allows enough
clearance for mounting accessories and for servicing.
Mounting
The ML6174/ML7174 Direct Coupled Actuators are designed
to open a damper by driving the damper shaft in either the
clockwise or counterclockwise direction. The actuator has a
mounting tab on the bottom that secures it to a damper box.
When mounted correctly, this tab allows the actuator to float
without rotating relative to the damper shaft. The tab is sized
for 1/4 in. (6 mm) self-tapping sheet metal screws (not
provided).
CAUTION
Equipment Damage Hazard.
Tightly securing mounting tab to damper housing
can damage actuator.
Do not fully tighten the screw, when mounting, to
allow the actuator to float.
ML6174 and ML7174 Direct Coupled Actuators are shipped in
the fully clockwise [cw arrow] 90°position as viewed from the
end of the damper actuator shaft.
CAUTION
Equipment Damage Hazard.
Mounting actuator unevenly with damper housing
can damage actuator.
Mount the actuator flush with the damper housing or
add a spacer between mounting tab and the damper
housing (see Fig. 2).
ADD SPACER BETWEEN
DAMPER BOX AND TAB
DAMPER
SHAFT
ML6174
VAV BOX HOUSING
M10245
Fig. 2. Mounting ML6174/ML7174 to VAV box when
actuator is not flush with box.
Preparation
Before mounting the actuator onto the damper shaft,
determine the following:
1. Size of the damper shaft (3/8 in. to 1/2 in.).
2. Direction the damper shaft rotates to open the damper
(cw or ccw). See Fig. 3.
3. Angle of the damper opening (45°, 60°, or 90°).
If the damper shaft is 3/8 in. round or square, use part
number 201391 Shaft Adapter provided inside the bag
assembly shipped with the actuator. Place the adapter
opposite the setscrews (see Fig. 4).
COOLING
AIR FLOW
COOLING
AIR FLOW
CW TO OPEN, CCW TO CLOSE
CCW TO OPEN, CW TO CLOSE M2067A
TYPE A DAMPER
TYPE B DAMPER
Fig. 3. Determining direction damper shaft rotates
when opening.

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—1 6
Fig. 4. Using damper shaft adapter for 3/8 in.
damper shafts.
Manual Operation (Declutch)
CAUTION
Personal Injury and Product Damage Hazard.
Do not use manual declutch without supporting
the load.
Support load independent of actuator immediately
prior to and while using manual declutch lever.
Use the manual declutch lever to manually adjust the actuator
setting. Fig. 5 shows the location of the manual declutch
lever. To operate, push the lever in the direction of the arrow
on the lever cover.
SHAFT ADAPTER
M2064
M10076A
MANUAL
DECLUTCH
LEVER
60°
60°
Fig. 5. Location of manual declutch lever.
Installation
After determining the direction of the damper shaft rotation
(cw or ccw), proceed as follows:
1. Place the actuator onto the damper shaft.
2. If the angle of the damper opening is 60°, close the
actuator using the manual declutch:
a. Disengage the hub using the declutch lever; see
Manual Operation (Declutch) section.
b. Rotate the hub until the actuator gear train
passes the 60°setting. (Do not insert the pin until
the actuator has passed this point.)
c. Release the declutch lever.
NOTE: Dampers with 90°stroke do not require the
range stop pin.
3. Insert the range stop pin into the appropriate (cw or
ccw) 60°slot. The range stop pin is clipped into its final
position only after the pin passes through both actuator
plates (see Fig. 6). The range stop pin should snap into
position and not be removable by hand (see Fig. 7).
4. With the actuator placed in its final position, secure the
mounting tab to the damper box with a sheet metal
screw.
CAUTION
Equipment Damage Hazard.
Tightly securing mounting tab to damper housing
can damage actuator.
Do not fully tighten the screw, when mounting, to
allow the actuator to float.
5. Position the damper in the open position and tighten
the Allen screws securely into the damper shaft.
6. If the angle of the damper opening is 45°, close the
actuator using the manual declutch.
a. Disengage the hub using the declutch lever; see
Manual Operation (Declutch) section.
b. Rotate the hub until the actuator gear train
passes the 45°setting. (Do not insert the pin until
the actuator has passed this point.)
c. Release the declutch lever.
7. Insert the range stop pin into the appropriate (cw or
ccw) 45°slot. The range stop pin is clipped into its final
position only after the pin passes through both actuator
plates (see Fig. 6). The range stop pin should snap into
position and not be removable by hand (see Fig. 7).
CAUTION
Equipment Damage Hazard.
Using incorrect range stop can damage light duty
dampers.
Be sure to select the correct range stop.
Minimum Position Setscrew
Certain ML6174 and all ML7174 models are equipped with
two tapped holes located in the plastic housing at the top of
the actuator. These holes can be used with the minimum
position setscrew and locknut inside the 4074ENJ Bag
Assembly (see Fig. 8). The setscrew provides for a 0°to 30°
minimum position adjustment.
NOTE: Before starting operation, note that the 1/4 in.
minimum position setscrew limits closing motion,
while the range stop pin limits opening motion.
1. Determine the direction of the desired closing rotation.
2. Move the actuator to the position fully opposite of the
desired closing rotation (if cw closing rotation is
desired, move the actuator to the full ccw position).
3. Establish the correct hole for the setscrew using Fig. 8
and the results of step 1.
4. Remove the red cap from the desired hole. Leave the
other cap in position. The caps ensure that dust and
other impurities do not enter the gear train through
unused holes.

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—17
5. Thread the locknut fully onto the setscrew.
6. Insert 1/4 in. setscrew into the desired hole, turning
clockwise until resistance is encountered or the locknut
contacts the housing.
7. If resistance is met before the setscrew is fully inserted,
stop and review the initial setup procedures as detailed
in steps 1 through 3.
CAUTION
Equipment Damage Hazard.
Improper actuator positioning or hole selection
can result in permanent damage to the actuator
and housing.
Avoid backdriving the actuator with the setscrew.
8. Determine the angle of minimum position required for
the application. With the setscrew fully inserted, the
minimum position is 30°. With the setscrew fully out, the
minimum position is 0°.
9. Using the conversion of approximately 1.7 angular
degrees per turn of the setscrew, back the screw out of
the housing and stop slightly short of the calculated
position. This allows for accurate setscrew setting while
taking air flow measurements.
IMPORTANT
After step 10 is initiated, the setscrew cannot be
turned back into the housing without returning the
actuator to the fully open position as determined in
step 1. The actuator will follow the setscrew without
damaging the housing only if the setscrew is backed
out of the housing (turned ccw).
10. Rotate the actuator to the minimum position using the
manual declutch, see Manual Operation (Declutch)
section.
11. After the actuator is at minimum position, adjust the
position more accurately by using air flow
measurements. After each adjustment, be sure to
check that the actuator is completely stopped before
proceeding with the next adjustment. To reduce the
minimum position, turn the setscrew out (ccw). The
actuator will drive toward the closed position. Turning
the setscrew in (cw) results in damage to the actuator
housing. If the damper is too far closed, return to
step 1.
12. When proper air flow is achieved, tighten the locknut
until it contacts the housing, then turn it an additional
1/8 turn to lock the setscrew in place.
NOTE: Be sure to completely check out the operation after
completing this procedure.
Wiring
CAUTION
Electrical Shock or Equipment Damage Hazard.
Can shock individuals or short equipment
circuitry.
Disconnect all power supplies before installation.
Motors with auxiliary switches can have more than
one disconnect.
60
45 45
60
CW
CCW
COM
RANGE STOP PIN
ACTUATOR PLATES
M10246A
Fig. 6. Range stop pin properly inserted.
SCREWDRIVER
M2065
Fig. 7. Lifting range stop pin out of its slot.
M10247
60
45
45
60
THIS SET SCREW
CORRESPONDS WITH
CLOSING IN THE
CW DIRECTION THIS SET SCREW
CORRESPONDS WITH
CLOSING IN THE
CCW DIRECTION
Fig. 8. Setscrew location for ML6174.

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—1 8
All wiring must comply with local electrical codes, ordinances
and regulations. Voltage and frequency of the transformer
used with the ML6174 must correspond with the
characteristics of the power supply and of the actuator. Screw
terminals are provided for easy hookup. See Fig. 10, 11 and
13-17 for typical wiring hookups.
Connecting Wiring to Conduit Cover Actuators
(Fig. 9)
1. Remove the cover from the actuator by lifting the top
and pivoting the cover to the rear of the actuator.
2. Remove the conduit knockouts with a flat-bladed
screwdriver. Discard the knockouts.
3. Install the conduit connector.
4. Run the connecting wire through the conduit connector,
strip the wire ends (if necessary) and connect to the
CW, COM and CCW terminals using Fig. 10, 11 or the
control manufacturer instructions.
COVER
M10075
CONDUIT
KNOCKOUTS
Fig. 9. Conduit cover for ML6174/ML7174 DCA.
Fig. 10. ML6174 used with T87F in heating or cooling application.
Fig. 11. ML6174 used with T87F in heating and cooling application.
5. Apply power to the actuator.
6. After operational checkout, replace the cover by
reversing the procedure in step 1.
Auxiliary Switches
The 201052A or B Auxiliary Switch is used with the ML6174/
ML7174 DCA. It allows for control of equipment external to
the actuator (for example, electric reheat coils and fan) at an
adjustable point in the actuator stroke (0°to 90°).
The 201052 Auxiliary Switches are field-addable. For
installation instructions, see form 63-2218.
Auxiliary Potentiometers
The 200976A,C Auxiliary Potentiometers mount on the face
of the ML6174A,C (as shown in Fig. 12). The potentiometer
shaft has a slipping collar. If one of the two limits of the
potentiometer is exceeded, the collar continues to rotate,
causing no damage to the potentiometer itself. To mount the
potentiometer on the actuator:
1. Turn the potentiometer to align the shaft key with the
slot in the potentiometer drive.
2. Tilt the potentiometer slightly so the key faces down
toward the slot.
3. Insert the potentiometer into the slot, and push down so
the potentiometer is flush with the actuator body and
the bracket is aligned over the screw hole.
4. Insert the provided screw into the hole and fasten
securely.
IMPORTANT
Remove the range stop pins and minimum position
setscrews prior to calibration.
M10248
EXTERNAL
SWITCH
R
W
Y
T87F
R8222
#1 #2
#3
RED COM
BLUE CW
WHITE CCW
L1
(HOT)
L2
1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
AUXILIARY SWITCHES ARE REQUIRED TO TURN
OFF THE MOTOR AT EACH END OF THE STROKE.
ML6174
M10249
R
W
Y
T87F
R8222
#1 #2
#3
RED COM
BLUE CW
WHITE CCW
L1
(HOT)
L2
1ML6174
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
AUXILIARY SWITCHES ARE REQUIRED TO TURN
OFF THE MOTOR AT EACH END OF THE STROKE.

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—19
IMPORTANT
Failure to follow the calibration procedures can
result in improper resistance values at the desired
stroke.
200976A,C Calibration
1. Drive the actuator fully closed (0°) to fully open (90°)
and back again to the fully closed position to receive
the correct resistance readings at the appropriate
degree of stroke.
2. Check the resistance values of the potentiometer with
an ohmmeter at intervals in the stroke while referring to
the table in Fig. 12 and feedback potentiometer ratings
in the Specifications section.
3. Replace the range stop pins and/or the minimum
position setscrews using the appropriate procedures.
60
45 45
60
CW
CCW
COM
M10251A
MOTOR
POSITION RW
RESISTANCE RB
RESISTANCE
FULL CW
24V (COM-CW)
FULL CCW
24V (COM-CCW) 0 OHMS
0 OHMS 500 OR
2000 OHMS
AUXILIARY POTENTIOMETER
MOTOR
ROTATION
AUXILIARY POTENTIOMETER LEADS
RW
OHMS RB
OHMS
CCW
CW
FIELD-ADDABLE AUXILIARY POTENTIOMETER
500 OR
2000 OHMS
BRW
Fig. 12. ML6174A,C with field-addable potentiometer.
OPERATION
VAV Systems
VAV systems control the temperature within a space by
varying the volume of supply air temperature. The system
delivers air to the space at a fixed temperature. The space
thermostat controls the volume of supply air by modulating
the supply air damper. When full heating and cooling flexibility
is required in a zone, it is handled by the air temperature
system, or with reheat capability in the air terminal units. As
individual zones shut down, a central duct static pressure
controller regulates the total air flow in the system. The fan
system is sized to handle an average peak load, not the sum
of the individual peaks. As each zone peaks at a different
time of day, extra air is borrowed from the off-peak zones.
This transfer of air from low-load to high-load zones occurs
only in true VAV systems.
In pressure-independent systems, individual zone airflow
sensors maintain the zone air flow rate regardless of
fluctuation in the total system pressure. When used with
controllers such as the W7620, pressure-independent
systems can react faster to changes in air flow demand;
therefore, these systems can use the faster 90-second
ML6174 models.
Pressure-dependent systems do not incorporate an individual
zone air flow sensor and depend on a stable system pressure
to maintain flow. These systems require slower actuators
such as the seven-minute ML6174 models that are typically
controlled by spdt floating wall thermostats.
The T641 is a mercury bulb floating control type thermostat
designed for use with the seven-minute ML6174 on pressure-
dependent systems (see Fig. 13 and 14). The T6984 is an
electronic floating control thermostat designed for use with
the 90-second and seven-minute ML6174 models (see
Fig. 15).
Parallel Actuators
IMPORTANT
Over time, multiple actuators with similar timing that
are driving in parallel may not be in sync with each
other. In normal operation, driving all actuators to the
fully open or fully closed position restarts them in
sync with each other.
ML6174 Actuators
Using Fig. 16, parallel the CW, COM and CCW terminals. Up
to five actuators can be wired in parallel. Make certain the
total connected load does not exceed the current capacity of
the controller or thermostat.

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—1 10
1
1
2
3
3
2
RCY W
T641A THERMOSTAT
1K
120
VAC
SYSTEM
TRANSFORMER
24 VAC
CCW CW
PHASE SHIFT CAP
DRIVE
CCW
WINDING
DRIVE
CW
WINDING
COM
ML6174 ACTUATOR
COMMON
USE NC CONTACT OF AUXILIARY SWITCH (PIN 201052A).
CONTACT OPENS WHEN ACTUATOR DRIVES CLOSED (CCW)
TO CAM SETTING POSITION.
USE SPDT RELAY OUTPUTS FROM FIRE AND ALARM
SYSTEM, OR OVERRIDE SYSTEM, AS DRAWN. THIS
OVERRIDES MINIMUM POSITION LIMITATION, AND
DRIVES ACTUATOR FULLY CCW.
AS DRAWN, ACTUATOR OPENS DAMPER TO CW ROTATION.
TO OPEN DAMPER TO CCW, REVERSE CCW AND CW
CONNECTIONS AT ACTUATOR. THIS ALSO CAUSES
ALARM CONDITION TO DRIVE ACTUATOR TO FULLY CW.
M10253B
Fig. 13. Minimum position set with auxiliary switch
contacts, override provided by fire and alarm contacts.
1
1
RCY W
T641A,C THERMOSTAT
120
VAC
SYSTEM
TRANSFORMER
24
VAC CCW CW
PHASE SHIFT CAP.
DRIVE
CCW
WINDING
DRIVE
CW
WINDING
COM
COMMON
AS SHOWN, T641 MAKES R-Y CONTACTS TO DRIVE
ML6174 ACTUATOR CCW, AND MAKES R-W CONTACTS
TO DRIVE ML6174 ACTUATOR CW. M12574
ML6174
ACTUATOR
Fig. 14. T641A,C controlling ML6174.
ML7174 Actuators
Voltage input (2 to 10 Vdc)
Wire the (+Vdc) and (-) terminals of each actuator in parallel.
Make certain the total connected load does not exceed the
current capacity of the input signal source.
1
1
2
2
L1
(HOT) 24 VAC
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION, AS REQUIRED.
T6984A SHOWN WIRED FOR COOLING ONLY. TO WIRE FOR
HEATING ONLY, REVERSE OPEN AND CLOSE CONTACTS. M12575
ML6174
CW
COM
CCW
L2
COMMON
24 VAC
MOTOR CLOSE
MOTOR OPEN
T6984A
Fig. 15. T6984A controlling ML6174 for cooling or
heating application.
1
1
RC YW
T641A,C THERMOSTAT
L1
(HOT) 24 VAC
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION, AS REQUIRED. ENSURE THAT
EQUIPMENT TRANSFORMER IS CORRECTLY SIZED. M12576
ML6174
CW
COM
CCW
ML6174
CW
COM
CCW
ML6174
CW
COM
CCW
L2
Fig. 16. Parallel ML6174 actuators from an
spdt controller.

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—111
Current input (4 to 20 mA)
When using a current controller (such as the W7600), parallel
the ML7174 voltage input terminals (+Vdc) and (-). Use a
bridging resistor in parallel with the 4 to 20 mA signal. See
Fig. 17 for resistor values.
NOTE: The actuator has 45,000 ohm impedance.
L1
(HOT)
L1
(HOT) L2
L2
1
2
3
3 3
2 2
1
ML7174 ACTUATORS CAN USE COMMON TRANSFORMER;
SEPARATE POWER SUPPLY REQUIRED FOR W7600.
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED. ASSURE THAT
EQUIPMENT TRANSFORMER IS SIZED CORRECTLY.
V1
V2
+
–
R
4-20 mA
ML7174
V
–
T1
T2
ML7174
V
–
T1
T2
ML7174
V
–
T1
T2
W7600
1 ML7174 R = 549 OHMS
2 ML7174 R = 549 OHMS
3 ML7174 R = 549 OHMS
4 ML7174 R = 576 OHMS
5 ML7174 R = 576 OHMS
6 ML7174 R = 576 OHMS
7 ML7174 R = 590 OHMS
8 ML7174 R = 604 OHMS
9 ML7174 R = 604 OHMS
10 ML7174 R = 619 OHMS
1/2 WATT
M10252A
Fig. 17. Parallel ML7174 actuators from a 4-20 mA
signal source.
CHECKOUT
ML6174 Checkout
1. Determine the direction the damper shaft moves to
open the damper (cw or ccw). See Fig. 3.
2. Place 24 volts across the appropriate common cw or
common ccw terminals to energize the actuator. The
ML6174 should begin to open the damper.
3. If the actuator does not run, try switching the 24 volts
across the opposite common cw or ccw terminals to
determine if the damper begins to close.
4. If the actuator does not run in either direction, replace
the ML6174.
NOTE: To check out ML6174 actuators controlled by
electronic control systems such as the W7620,
override the control system by programming the
controller to open or close the zone damper, as
appropriate.
For an ML6174 issued with an spdt floating wall thermostat
(for pressure-dependent systems), use the following checkout
procedure:
1. Adjust the setpoint of the thermostat to call for cooling.
2. Observe the operation of the actuator; if the damper is
closed, it should begin to open.
3. If not, adjust the setpoint of the thermostat higher to
determine if the wiring is correct.
4. If no movement is observed, check for the presence of
24 volts.
5. If using the T641 Thermostat, the 24 volts should be
present between terminals C and Y during a call for
cooling. With proper wiring and 24 volts present, the
actuator should operate correctly. If not, replace the
actuator.
NOTE: Using a seven-minute actuator results in a longer
response time before noticeable damper movement.
ML7174 Checkout
Check input impedance on the ML7174 with an ohmmeter.
IMPORTANT
Be sure to disconnect all wiring to the actuator
before connecting the ohmmeter.
1. Verify resistance readings are as follows:
45K ohms ±5K ohms, across the (+Vdc) and (-) terminals.
536 ohms ±10 ohms, across the (+mA) and (-) terminals.
2. If the resistance readings are correct, reconnect the
actuator and check for 24 Vac at terminals T and T2.
With the correct power present at T and T2, check the
motion of the damper/actuator by ramping the setpoint
up and down. This causes the actuator to move from
one limit to the other and back (from fully ccw to fully
cw and back to fully ccw).
NOTE: Remember that the ML7174 takes 90 seconds
to move from one limit to the other.
3. When the ML7174 is used with electronic control
systems such as the W7600 Commercial Zone System,
override the control system by programming the
controller to open or close the damper, as appropriate.
4. If the actuator continues to operate incorrectly, check
Table 1 for the proper input signal/actuator drive
relationship at the (+Vdc) and (-) terminals.
5. If the ML7174 does not operate according to Table 1
values, replace the actuator.
Table 1. Input Signal/Actuator Drive Relationship.
Input Signal Actuator Drive Relationship
1.50 ±0.2 Vdc Actuator drives to extreme ccw
position.
2.00 ±0.2 Vdc Actuator remains at ccw position.
3.00 ±0.2 Vdc Actuator leaves ccw position.
10.70 ±0.7 Vdc Actuator drives to extreme cw
position.
10.00 ±0.7 Vdc Actuator remains at cw position.
8.50 ±0.6 Vdc Actuator leaves cw position.

ML6174, ML7174 NON-SPRING RETURN DIRECT COUPLED ACTUATORS
63-2534—1 12
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3 Avenue du Bourget
1140 Brussels
Belgium
Honeywell Asia Pacific Inc.
Room 3213-3225
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Wanchai
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Home and Building Control
Honeywell Limited-Honeywell Limitée
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M2H 3N7
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Suite 200
Sunrise FL 33325
63-2534—1 B.B.Rev.12-97 Printed in U.S.A.
Home and Building Control
Honeywell Inc.
Honeywell Plaza
P.O. Box 524
Minneapolis MN 55408-0524
www.honeywell.com