# Valve Actuator (Modulating) - Quick Reference SSO **Device Type:** Analog Output - Actuator **Signal:** 0-10VDC / 2-10VDC / 4-20mA input **Power:** 24VAC (most common) / 24VDC / 120VAC **Version:** 1.0 | **Date:** Dec 2025 --- ## DEVICE OVERVIEW **Common Models:** - Belimo LRB24, NRB24, TRB24, Johnson Controls VA-7000, Honeywell ML6420/ML7420, Siemens SKC/SKD **Used For:** Chilled water valves, hot water valves, condenser water valves, steam valves, glycol loops **Specifications:** - **Force:** 90-500 lbs (match to valve size) - **Stroke:** 1/2" to 2" typical - **Stroke Time:** 30-180 seconds typical - **Fail Mode:** 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:** 32°F to 125°F ambient, valve body may be hotter --- ## SAFETY - PPE REQUIRED - ☑ Safety glasses (ANSI Z87.1) - ☑ Heat-resistant gloves (pipes may be hot - up to 200°F) - ☑ Hard hat (mechanical rooms) - ☑ Face shield (if system under pressure) ### HAZARDS - ⚠ **HOT SURFACES** - Hot water pipes (up to 200°F), steam pipes (up to 250°F+) - ⚠ **COLD SURFACES** - Chilled water pipes (35-45°F) - risk of cold burns with prolonged contact - ⚠ **PRESSURIZED SYSTEMS** - Water systems under 30-150 PSI - ⚠ **PINCH POINTS** - Valve stem moves with force - ⚠ **CHEMICAL EXPOSURE** - Glycol, water treatment chemicals (if leak occurs) ### SYSTEM ISOLATION - [ ] **NOT typically required** for actuator replacement (if valve can stay in place) - [ ] **REQUIRED if removing valve:** Coordinate with building operator - [ ] Close isolation valves upstream and downstream - [ ] Drain/depressurize section of piping - [ ] Keep drain bucket ready in case of residual water --- ## INSTALLATION CHECKLIST ### TOOLS NEEDED - Adjustable wrenches (two - for coupling nuts) - Allen wrenches (actuator mounting) - Wire strippers (18-16 AWG) - Multimeter (DMM) - Label maker - Teflon tape or pipe dope (if removing valve) - Bucket/rags (for water drainage) ### MATERIALS - Coupling hardware (included with actuator) - Wire nuts or terminal blocks - Cable ties - Mounting bracket (if needed) ### PRE-INSTALL - [ ] Verify actuator force rating matches valve size - [ ] Confirm actuator stroke length matches valve stem travel - [ ] Check control signal type matches actuator input - [ ] Verify fail-safe requirement (spring return vs non-spring) - [ ] Verify valve accessible and piping supported - [ ] Note current valve position (for reference) ### INSTALL STEPS 1. **Remove old actuator** (if replacement): - Manually position valve mid-stroke (ease spring tension) - Disconnect wiring, label if reusing - Remove coupling from valve stem - Remove actuator from mounting bracket - **CAUTION:** Spring return actuators have spring tension - control release 2. **Inspect valve stem:** - Check stem clean, no corrosion or damage - Verify stem moves freely (manually push/pull) - If seized: Valve needs service before actuator install - Check packing gland not leaking 3. **Mount actuator:** - Position actuator on mounting bracket (yoke) - Align actuator shaft with valve stem - Install coupling per manufacturer: * Direct couple: Thread onto stem or use clamp * Universal joint: Connect both ends - Verify actuator cannot slide off stem 4. **Set stroke limits** (if adjustable): - Manually position valve to full closed - Adjust actuator closed stop (if available) - Manually position valve to full open - Adjust actuator open stop - Verify stroke length matches valve travel (1/2" to 2" typical) 5. **Route and terminate wiring:** - **3-Wire Standard:** * Red: +24VAC/VDC power * Black/Blue: Common * White/Green: Control signal (0-10V / 2-10V / 4-20mA) - **4-Wire with Feedback:** * Add Yellow/Orange: Position feedback signal - Tighten terminals: 7-9 in-lbs - Support wire away from hot pipes with cable ties - Leave 12" service loop 6. **Label wiring:** - Example: "AHU-1-CHWV" (AHU-1 Chilled Water Valve) - Label both ends clearly ### POST-INSTALL - [ ] Actuator mounted securely on valve - [ ] Coupling tight on valve stem (no slipping) - [ ] All wires terminated tight (7-9 in-lbs) - [ ] Labels applied both ends - [ ] Stroke limits set correctly - [ ] No water leaks at packing gland - [ ] Wiring routed away from hot surfaces - [ ] Work area cleaned - [ ] Photos taken --- ## EXPECTED READINGS ### PRE-POWER (Power OFF) - **Continuity:** Each wire <5 ohms end-to-end - **Isolation:** >10K ohms to ground - **Valve Movement:** Stem moves freely by hand, no binding - **Spring Return Test:** If SR model, valve returns to fail-safe position when actuator removed ### POWER-UP - **Supply Voltage:** 24VAC/VDC ±10% (21.6-26.4V) or 120VAC ±10% - **Power Consumption:** 3-8 VA (24V) or 10-15 VA (120V) typical - **Control Signal Range:** * 0-10VDC: 0V = closed, 10V = open * 2-10VDC: 2V = closed, 10V = open * 4-20mA: 4mA = closed, 20mA = open ### POSITION VERIFICATION | Control Signal | Expected Position | Feedback Signal | |---------------|-------------------|-----------------| | 0V / 2V / 4mA | 0% (Closed) | 0V / 2V | | 5V / 6V / 12mA | 50% (Half-open) | 5V / 6V | | 10V / 10V / 20mA | 100% (Open) | 10V / 10V | **Stroke Time:** 30-180 seconds full travel (depends on model) --- ## PROOF OUT TESTS ### TEST 1: Manual Override Test (if equipped) - **Do:** Engage manual override lever on actuator - **Expect:** Actuator can be manually positioned, motor disengaged - **Pass If:** Manual override works, returns to auto when released ### TEST 2: Full Stroke Test - **Do:** Command actuator from controller: 0% → 100% → 0% - **Expect:** * Smooth, continuous movement (no jerking) * Stroke time within spec (30-180 sec) * Position indicator moves smoothly * Valve stem moves full travel distance - **Pass If:** Completes full stroke both directions within spec time ### TEST 3: Position Accuracy Test - **Do:** Command 0%, 25%, 50%, 75%, 100% - **Expect:** Actuator stops at each position, feedback matches command - **Pass If:** Position within ±5% of commanded ### TEST 4: Water Flow Verification - **Do:** Stroke valve while observing: * Supply/return temperature differential (ΔT) * Flow meter reading (if available) * Coil performance (heating/cooling output) - **Expect:** * 0% position: Minimum flow, maximum ΔT * 100% position: Maximum flow, minimum ΔT * Gradual change between positions - **Pass If:** Flow control is proportional to valve position ### TEST 5: Fail-Safe Test (Spring Return models) - **Do:** Remove power while actuator at mid-position - **Expect:** Actuator returns to fail-safe position: * Cooling valves: Typically close (NC) * Heating valves: May close or open depending on application - **Pass If:** Returns to fail-safe within 30 seconds, stays in position ### TEST 6: No Leak Test - **Do:** Observe valve packing gland during full stroke - **Expect:** No water dripping from stem - **Pass If:** Packing gland remains dry through full operation ### TEST 7: Controller Integration - [ ] 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 PID loop control - [ ] No faults or errors --- ## TROUBLESHOOTING ### NO POWER / ACTUATOR DEAD 1. Measure supply voltage at actuator: 24VAC/VDC or 120VAC ±10% 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 commanded (should hear humming) 6. **If voltage present but no sound:** Replace actuator (motor failed) ### ACTUATOR RUNS BUT VALVE DOESN'T MOVE 1. **Check coupling:** May have loosened or stripped 2. **Manually try to move stem:** Should feel resistance from actuator 3. **Check valve stem:** May be seized or broken 4. **If coupling loose:** Tighten or replace 5. **If stem seized:** Valve needs service/rebuild 6. **If stem broken:** Valve replacement required ### ACTUATOR MOVES BUT INCORRECT POSITION 1. Verify control signal at actuator terminals 2. **If signal correct but position wrong:** Check stroke limits 3. Adjust stroke limits to match valve travel 4. Verify coupling not slipping on stem 5. Check position feedback wiring (if equipped) 6. **If feedback wrong:** Check feedback wire, verify at controller ### ACTUATOR STALLS OR BINDS 1. Check valve for physical problems: - Stem bent or damaged - Internal valve parts seized or broken - Packing gland too tight 2. Measure current draw: >300mA indicates overload 3. **If overcurrent:** Valve too large for actuator or valve needs service 4. **If binding specific position:** Adjust stroke limits 5. **If generally binding:** Service valve or replace actuator with higher force ### SLOW MOVEMENT 1. Measure supply voltage under load: Should stay ±10% 2. Check for voltage drop in long wire runs 3. Verify control signal stable 4. Listen for motor sounds (grinding indicates wear) 5. **If voltage drops:** Increase wire gauge 6. **If motor sounds bad:** Replace actuator (gearbox failing) ### WATER LEAKING FROM VALVE STEM 1. **NOT an actuator issue** - packing gland needs adjustment 2. Slightly tighten packing nut (1/4 turn at a time) 3. **If still leaking:** Packing needs replacement (coordinate with plumber) 4. **CAUTION:** Over-tightening can bind valve stem ### VALVE WON'T CLOSE FULLY (Leaking Thru) 1. **NOT typically actuator issue** - valve seat worn or damaged 2. Verify actuator reaching full closed position (0% command) 3. If actuator at 0% but water still flowing: Valve needs service/replacement 4. **Temporary workaround:** Slightly over-close using controller offset (if available) ### ACTUATOR WON'T RETURN TO FAIL-SAFE (SR) 1. Remove power and manually feel spring tension 2. **If no spring:** Spring broken - replace actuator 3. **If valve won't move:** Valve may be too tight for spring force 4. Check for valve binding preventing spring return --- ## ESCALATION - COMPLETE BEFORE CALLING ### PRE-ESCALATION CHECKLIST - [ ] Verified supply voltage at actuator (24V or 120V ±10%) - [ ] Verified control signal at actuator terminals - [ ] Checked coupling tight on valve stem - [ ] Tested actuator manually (override if equipped) - [ ] Observed valve stem movement through full stroke - [ ] Checked for valve binding or stem damage - [ ] Verified no water leaks at packing gland - [ ] Documented actual stroke time - [ ] Taken photos of installation - [ ] Reviewed actuator installation manual ### PROVIDE THIS INFO - **Actuator:** [Mfg / Model / Force Rating / Location] - **Valve:** [Type / Size / Normally Open or Closed] - **Application:** Chilled water / Hot water / Steam / Condenser water - **Supply Voltage:** _____ VAC/VDC - **Control Signal:** 0-10V / 2-10V / 4-20mA - **Commanded Position:** _____ % - **Actual Position:** _____ % (visual or feedback) - **Stroke Time:** _____ seconds (0-100%) - **Water Temperature:** _____ °F (supply and return) - **ΔT:** _____ °F (supply - return) - **Symptoms:** [Not moving, slow, binding, leaking, etc.] - **Steps Taken:** [Troubleshooting completed] - **Photos:** Attached ### CONTACTS - **Field Specialist:** [Phone] - **Programmer:** [Phone] (if PID loop tuning issue) - **Project Manager:** [Phone] (if wrong actuator size) - **Dispatch:** [Phone] --- ## COMMON ISSUES & TIPS ✓ **Actuator sizing:** 90-150 lbs for 2-way valves up to 2", 200-500 lbs for larger or 3-way valves ✓ **Spring return vs non-spring:** SR for fail-safe (cooling valves close on power loss) ✓ **Normally Open vs Normally Closed valve:** Must match application (NC for cooling typical) ✓ **2-10V vs 0-10V:** 2-10V preferred - provides broken wire detection ✓ **Stroke time:** Longer stroke time (90-180 sec) prevents water hammer ✓ **Hot pipes:** Route wiring away from pipes >140°F to prevent insulation damage ✓ **Valve cycling:** Excessive cycling (>6 per hour) indicates PID loop needs tuning ✓ **Position feedback:** Essential for accurate control - use 4-wire actuator ✓ **Packing gland:** Light leak from packing is normal, but excessive leak needs adjustment ✓ **Manual override:** Use during commissioning to verify valve operation ✓ **Glycol systems:** More viscous than water, may require longer stroke time --- **Document ID:** SSO-VALVE-001 **Revision:** 1.0 **Next Review:** Dec 2026