**Device Type:** Analog Output - Actuator

**Signal:** 0-10VDC / 2-10VDC / 4-20mA input

**Power:** 24VAC (most common) / 24VDC

**Version:** 1.0 | **Date:** Dec 2025

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**Common Models:**

- Belimo LMB24-SR, LRB24, NMB24, Johnson Controls M9000, Honeywell MS7505/MS8105, Siemens GCA/GMA

**Used For:**

OA/RA/EA damper control (economizer), mixing box dampers, VAV box dampers, bypass dampers

- **Torque:** 35-150 in-lbs (match to damper size)

- **Stroke Time:** 60-90 seconds typical

- **Rotation:** 90° (spring return "SR" or non-spring "NSR")

- **Wire Type:** 18AWG minimum for control, 16AWG for power

- **Wiring:** 3-wire (power, common, control) or 4-wire (+ position feedback)

**Environment:** -40°F to 120°F, NEMA 2 (indoor) / NEMA 4 (outdoor)

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- ☑ Safety glasses (ANSI Z87.1)

- ☑ Cut-resistant gloves

- ☑ Hard hat (required in mechanical rooms/rooftops)

- ☑ Fall protection (if working >6 feet)

- ⚠ **ROTATING EQUIPMENT** - Air handler fans, belts, pulleys (LOCKOUT REQUIRED)

- ⚠ **PINCH POINTS** - Damper blades close with force, keep hands clear

- ⚠ **SHARP EDGES** - Sheet metal ductwork and damper frames

- ⚠ **WORKING AT HEIGHTS** - Rooftop units, catwalks, ladders

- ⚠ **HOT/COLD SURFACES** - Near heating coils or chilled water

- [ ] **MANDATORY:** Lock out air handler/RTU before working on dampers

- [ ] Notify building operator

- [ ] Switch unit to OFF or manual mode

- [ ] Lock breaker/disconnect with personal lock

- [ ] Test that fan will not start

- [ ] Keep key with you at all times

- [ ] Remove lock only after work complete and area safe

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- Cordless drill + bits

- Socket set (for coupling)

- Allen wrenches (actuator mounting)

- Wire strippers (18-16 AWG)

- Adjustable wrench

- Multimeter (DMM)

- Label maker

- Thread sealant (outdoor apps)

- Coupling hardware (included with actuator)

- Sheet metal screws

- Wire nuts or terminal blocks

- Cable ties

- Mounting bracket (if needed)

- Damper linkage (if replacing)

- [ ] **LOCKOUT air handler/RTU** before starting

- [ ] **Verify actuator torque rating matches damper size**

- [ ] **Confirm actuator rotation matches damper (CW/CCW)**

- [ ] Check control signal type matches actuator input (0-10V / 2-10V / 4-20mA)

- [ ] Verify fail-safe requirement (spring return vs non-spring)

- [ ] Damper accessible and safe to work on

1. **Remove old actuator** (if replacement):

- Disconnect wiring, label if reusing

- Remove coupling from damper shaft

- Remove actuator from mounting bracket

2. **Prepare damper shaft:**

- Clean shaft of rust, paint, debris

- Verify shaft rotates freely by hand

- Check damper blades not bent or binding

- Lubricate shaft bushings if needed

3. **Mount actuator:**

- Position actuator on mounting bracket

- Align actuator shaft with damper shaft

- Install coupling per manufacturer instructions

- Tighten coupling set screws (do not overtighten)

- Verify actuator cannot slip on shaft

4. **Set mechanical stops** (if adjustable):

- Manually position damper to full closed

- Adjust actuator closed stop to match

- Manually position damper to full open

- Adjust actuator open stop to match

- Verify 90° rotation matches damper travel

5. **Route and terminate wiring:**

* Red: +24VAC/VDC power

* Black/Blue: Common

* White/Green: Control signal (0-10V / 2-10V / 4-20mA)

* Add Yellow/Orange: Position feedback signal

- Tighten terminals: 7-9 in-lbs

- Support wire with cable ties

- Leave 12" service loop

6. **Label wiring:**

- Example: "AHU-1-OAD" (AHU-1 Outside Air Damper)

- Label both ends clearly

7. **Restore system:**

- Remove lockout device

- Notify operator

- Verify fan starts normally

- [ ] Actuator mounted securely

- [ ] Coupling tight on damper shaft (no slipping)

- [ ] All wires terminated tight (7-9 in-lbs)

- [ ] Labels applied both ends

- [ ] Mechanical stops set correctly

- [ ] Work area cleaned

- [ ] Photos taken

- [ ] System restored and operating

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- **Continuity:** Each wire <5 ohms end-to-end

- **Isolation:** >10K ohms to ground (all wires)

- **Damper Movement:** Rotates freely by hand, no binding

- **Spring Return Test:** If SR model, damper returns to fail-safe position when power removed

- **Supply Voltage:** 24VAC/VDC ±10% (21.6-26.4V acceptable)

- **Power Consumption:** 3-8 VA typical

* 0-10VDC: 0V = closed, 10V = open

* 2-10VDC: 2V = closed, 10V = open

* 4-20mA: 4mA = closed, 20mA = open

| Control Signal | Expected Position | Feedback Signal (if equipped) |

|---------------|-------------------|-------------------------------|

| 0V / 2V / 4mA | 0% (Closed) | 0V / 2V |

| 5V / 6V / 12mA | 50% (Mid) | 5V / 6V |

| 10V / 10V / 20mA | 100% (Open) | 10V / 10V |

**Stroke Time:** 60-90 seconds full travel (0-100%)

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- **Do:** Engage manual override switch/button on actuator

- **Expect:** Actuator can be manually positioned, motor disengaged

- **Pass If:** Manual override works, returns to auto when released

- **Do:** Command actuator from controller: 0% → 100% → 0%

* Smooth, continuous rotation (no jerking or binding)

* 60-90 second stroke time each direction

* Position indicator moves smoothly

* Damper blades visible moving through full range

- **Pass If:** Completes full stroke both directions within spec time

- **Do:** Command 0%, 25%, 50%, 75%, 100%

- **Expect:** Actuator stops at each position, feedback (if equipped) matches command

- **Pass If:** Position within ±5% of commanded (±4.5° for 90° rotation)

- **Do:** Stroke actuator full range while observing damper blades

* All blades move together (parallel operation)

* Blades seal tight at closed position

* No binding or interference at any position

* Linkage does not slip or flex excessively

- **Pass If:** All blades operate correctly through full range

- **Do:** Remove power while actuator at mid-position

- **Expect:** Actuator returns to fail-safe position (typically closed for OA dampers)

- **Pass If:** Returns to fail-safe within 15 seconds, stays in position

- [ ] Actuator appears in controller output list

- [ ] Controller can command actuator (0-100%)

- [ ] Position feedback reads correctly (if equipped)

- [ ] Graphics show live position

- [ ] Actuator responds to automatic control sequences

- [ ] No faults or errors

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1. Measure supply voltage at actuator terminals: 24VAC/VDC ±10%

- **If no voltage:** Check controller output, circuit breaker, wiring

2. Test continuity of power wiring end-to-end: <5 ohms

3. Check terminal connections tight

4. Verify polarity (DC circuits)

5. Listen for motor sound when power applied (should hear humming)

6. **If voltage present but no sound:** Replace actuator (motor failed)

1. **Check coupling:** Tighten set screws (may have loosened)

2. **Manually rotate actuator:** Should feel resistance (motor engaged)

3. **Check damper shaft:** May be disconnected from blades inside duct

4. **Check linkage:** Rods or arms may be disconnected or broken

5. **If coupling slipping:** Reposition and tighten, may need new coupling

6. **If shaft broken:** Requires damper disassembly/replacement

1. Verify control signal at actuator terminals:

- 0V/2V/4mA = Closed

- 10V/10V/20mA = Open

- **If signal correct but position wrong:** Check mechanical stops

2. Adjust mechanical stops to match damper travel

3. Verify coupling aligned correctly (0° = closed, 90° = open)

4. Check position feedback wiring (if equipped)

5. **If position feedback wrong:** Verify feedback wire connected, check at controller

6. **If mechanical stops maxed out:** May need larger torque actuator

1. Check damper blades for physical obstruction

2. Verify linkage not bent or binding

3. Check shaft bushings not seized

4. Measure current draw: >300mA indicates overload

5. **If overcurrent:** Damper too large for actuator torque rating

6. **If binding at certain position:** Adjust linkage or repair damper

7. **If generally binding:** Lubricate shaft bushings, check alignment

1. Measure supply voltage under load: Should stay within ±10%

2. Check for voltage drop in long wire runs

3. Verify control signal stable (not fluctuating)

4. Listen for unusual motor sounds (grinding, clicking)

5. Check gearbox for wear or damage

6. **If voltage drops:** Increase wire gauge or add local power supply

7. **If motor sounds bad:** Replace actuator (gearbox failing)

1. Remove power and manually feel spring tension

2. **If no spring tension:** Spring broken - replace actuator

3. **If spring weak:** May be old actuator, replace

4. Check for mechanical binding preventing spring return

5. Verify damper not too large for spring force

1. Verify feedback wire connected properly

2. Measure feedback signal at actuator: Should match position (0-10V or 2-10V)

3. Measure feedback signal at controller: Should match actuator reading

4. **If different at controller:** Wiring issue, check for shorts or high resistance

5. **If same but wrong:** Feedback potentiometer may be misaligned

6. **If no feedback signal:** Replace actuator (feedback pot failed)

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- [ ] Verified supply voltage at actuator (24VAC/VDC ±10%)

- [ ] Verified control signal at actuator terminals

- [ ] Checked coupling tight on damper shaft (no slipping)

- [ ] Verified all wire connections tight and correct

- [ ] Tested actuator manually (override if equipped)

- [ ] Observed damper blades moving through full range

- [ ] Checked for physical obstructions or binding

- [ ] Documented actual stroke time

- [ ] Taken photos of installation and linkage

- [ ] Reviewed actuator installation manual

- **Device:** [Mfg / Model / Torque Rating / Location]

- **Damper:** [Type: OA/RA/EA / Size / Blade count]

- **Supply Voltage:** _____ VAC/VDC

- **Control Signal Range:** 0-10V / 2-10V / 4-20mA

- **Commanded Position:** _____ %

- **Actual Position:** _____ % (visual or feedback)

- **Stroke Time:** _____ seconds (0-100%)

- **Symptoms:** [Specific problem - not moving, slow, binding, etc.]

- **Current Draw:** _____ mA (if measurable)

- **Steps Taken:** [Troubleshooting completed]

- **Photos:** Attached to Service Fusion ticket

- **Field Specialist:** [Phone]

- **Programmer:** [Phone] (if control sequence issue)

- **Project Manager:** [Phone] (if wrong actuator size/type)

- **Dispatch:** [Phone] (parts/resources)

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✓ **Coupling slipping:** Use Loctite on set screws, tighten to spec (don't overtighten)

✓ **Actuator too small:** Check damper size vs torque rating (35 in-lbs per ft² of damper area)

✓ **Spring return vs non-spring:** SR for fail-safe applications (OA dampers close on power loss)

✓ **2-10V vs 0-10V:** 2-10V provides feedback if wire breaks (will read 0V = alarm)

✓ **Mechanical stops:** Set stops to match damper travel (prevents over-rotation)

✓ **Outdoor applications:** Use NEMA 4 rated actuator, apply thread sealant

✓ **Linkage alignment:** Ensure damper blades parallel to each other through full stroke

✓ **Feedback wiring:** If 4-wire, feedback goes to AI input on controller (separate from command AO)

✓ **Stroke time adjustment:** Some models have adjustable stroke time (check manual)

✓ **Cold weather:** Actuators may be slower in extreme cold (-40°F), allow extra time

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**Document ID:** SSO-DAMPER-001

**Revision:** 1.0

**Next Review:** Dec 2026