This article addresses actuator drive time specifications for VAV controllers and the practical realities of available products.
Drive time (also called stroke time) is the time required for an actuator to travel from fully closed to fully open (or vice versa).
| Term | Definition |
|---|---|
| Drive Time | Full stroke duration (0-100%) |
| Stroke Time | Same as drive time |
| Travel Time | Time for partial movement |
| Response Time | Time to begin movement after signal |
| Manufacturer | Product | Typical Drive Time |
|---|---|---|
| Schneider | SpaceLogic VAV | 150-180 seconds |
| Belimo | VAV compact | 90-150 seconds |
| Johnson Controls | VMA | 90-150 seconds |
| Honeywell | Spyder VAV | 120-180 seconds |
| Distech | EC-VAV | 120-150 seconds |
Reality: Most integrated VAV actuators have drive times of 90-180 seconds.
| Type | Drive Time Range | Notes |
|---|---|---|
| Standard 24V | 90-180 sec | Most common |
| Spring Return | 15-30 sec (close) | Spring-assisted one direction |
| Fast-Acting | 35-90 sec | Available but more expensive |
| Electronic Fail-Safe | 3-5 sec (close) | Emergency/safety applications |
For integrated VAV: Generally no - standard products don't offer this.
For standalone actuator + controller: Yes, but with trade-offs.
Use standalone controller with fast actuator:
Trade-off: Higher cost, more wiring, larger physical size
Spring return actuators close very fast (spring-assisted):
Trade-off: Fast in one direction only
Before engineering alternatives, clarify the requirement:
Questions to ask the consultant:
For typical VAV applications:
| Consideration | Why 150 sec is Usually OK |
|---|---|
| Zone response | Thermal mass of space is slow |
| Duct pressure | System response is gradual |
| Comfort | Slow changes feel more natural |
| Noise | Fast actuators can be louder |
| Wear | Slower = longer life |
Exception: Fast response needed for:
Prepare technical submittal noting:
| Option | Drive Time | Cost Impact | Recommendation |
|---|---|---|---|
| Standard integrated | 150 sec | Baseline | Most applications |
| Fast standalone | 35-90 sec | +50-100% | Special requirements |
| Spring return | ~20 sec (close) | +30% | Fail-safe needs |
Submit RFI (Request for Information) to design team:
When searching for specific actuator capabilities:
Tip: Drive time is typically listed under "Timing" or "Operating Time" in actuator specifications.