UL 555S Listed · Fire & Smoke · 24 Vac
HAC-90
HAC-90
Belimo FSLF24 US
Fire & Smoke Damper
UL 555S Listed Actuator · Spring Return · 24 Vac · 6"–20"
✓Belimo FSLF24 US — UL 555S listed smoke damper actuator
✓Tested to UL 555S: torque, actuation speed, elevated temperature, smoke-laden air construction
✓Spring return fail-safe — blade moves to fail-safe position on signal loss
✓PO or PC — action code from fire protection engineer in writing before ordering
✓End switch available — wiring per smoke control system design
✓Heat bypass (−H) available — confirm with fire protection engineer before specifying
✓6"–20" even-inch increments
Is this the right product?
✔ Right product if
The project requires a UL 555S listed actuator for a smoke damper application — code, specification, or AHJ mandates a listed smoke damper actuator at 24 Vac.
✗ Not this product if
Standard fresh air, ventilation, or zone control — no smoke listing required → use HAC-40 (TFB24) at significantly lower cost.
Line voltage (120 Vac) smoke damper → use HAC-80 (FSLF120 US)
Line voltage (120 Vac) smoke damper → use HAC-80 (FSLF120 US)
What It Does
UL 555S listed. The actuator a smoke damper application actually requires — not just any spring return.
Do Not Substitute HAC-40 (TFB24) on Smoke Damper Applications
The standard Belimo TFB24 is NOT UL 555S listed and does NOT qualify for smoke damper service. Substituting TFB24 for FSLF24 US on a code-required smoke damper application will not pass inspection. The AHJ will require replacement with a listed actuator. The cost of replacement — actuator, labour, project delay, re-inspection — substantially exceeds the price premium of specifying the HAC-90 correctly the first time.
Action Code (PO/PC) — From the Fire Protection Engineer in Writing
Do not assume or default to PO or PC. The fail-safe direction on a smoke damper is a life-safety decision that affects the building's smoke control performance, certificate of occupancy, and building owner liability. A smoke damper with the wrong action code moves to the wrong position in a fire event. Get the action code from the fire protection engineer in writing before ordering.
The HAC-90 pairs Hoyme's inline damper body with the Belimo FSLF24 US — a UL 555S listed fire and smoke actuator designed specifically for smoke damper service. The FSLF designation is not a marketing label. It means the actuator has been tested and listed to UL Standard 555S — the standard for smoke damper actuators — covering specific torque requirements, maximum actuation speed to reach fail-safe position, elevated temperature performance, and construction requirements for operation in smoke-laden air.
What UL 555S Listing Actually Requires
Four requirements that standard on/off actuators are not tested or required to meet.
| UL 555S Requirement | HAC-40 (TFB24) | HAC-90 (FSLF24 US) |
|---|---|---|
| UL 555S Listed | No — not submitted for testing | Yes — listed smoke damper actuator |
| Minimum Torque | Standard — not UL 555S tested | Meets UL 555S minimum torque requirements |
| Maximum Actuation Time to Fail-Safe | Standard — not UL 555S tested | Meets UL 555S maximum time-to-fail-safe |
| Elevated Temperature Performance | Standard HVAC range only | Tested to UL 555S elevated temperature requirements |
| Construction for Smoke-Laden Air | Not required — standard HVAC | Constructed for operation in smoke-laden airstream |
| Application | Fresh air, ventilation, zone control | Smoke damper applications requiring UL 555S |
| Acceptable Substitute for FSLF24? | Never — not listed | N/A — this is the correct product |
Smoke Control System Integration
The HAC-90 does not operate independently — it integrates into the building's smoke control system.
The smoke control sequence is managed by the building fire alarm system and smoke control panel. The FSLF24 US actuator receives its fail-safe signal from the smoke control panel, not from a standard HVAC controller or BAS. The installation contractor must coordinate with the fire protection engineer and the fire alarm system installer on the control wiring, the fail-safe signal source, and the verification sequence required by the smoke control commissioning plan.
End switch wiring: The end switch on the HAC-90 provides position feedback to the fire alarm or smoke control system — confirming the damper responded to the control signal. End switch wiring requirements are specified by the smoke control system design, not by the HVAC contractor's preference. Confirm end switch wiring requirements with the fire protection engineer before ordering.
Configuration Guide
Action code confirmed by fire protection engineer. End switch wiring per smoke control system design. −H requires explicit fire protection engineer confirmation.
| Variant Code | Action | End Switch | Heat Bypass | Part Number Example (10") |
|---|---|---|---|---|
| OPO | Spring-open on power loss | No | No bypass | HAC-1090-OPO |
| OPO-H | Spring-open on power loss | No | 10% bypass | HAC-1090-OPO-H |
| SPO | Spring-open on power loss | Yes | No bypass | HAC-1090-SPO |
| SPO-H | Spring-open on power loss | Yes | 10% bypass | HAC-1090-SPO-H |
| OPC | Spring-close on power loss | No | No bypass | HAC-1090-OPC |
| OPC-H | Spring-close on power loss | No | 10% bypass | HAC-1090-OPC-H |
| SPC | Spring-close on power loss | Yes | No bypass | HAC-1090-SPC |
| SPC-H | Spring-close on power loss | Yes | 10% bypass | HAC-1090-SPC-H |
−H Heat Bypass on Smoke Dampers — Confirm with Fire Protection Engineer: On a smoke damper application, specifying −H is unusual — smoke dampers are typically required to provide full shutoff or full opening on the fire signal. The bypass maintains a 10% permanent opening that may conflict with the smoke damper's required performance under UL 555S. Do not specify −H on smoke damper applications without explicit confirmation from the fire protection engineer.
Part Number Decoder
HAC-1490-SPO
HAC
Product family: universal inline air control damper
14
Size (2-digit): 06=6", 08=8", 10=10", 12=12", 14=14", 16=16", 18=18", 20=20"
90
Motor code: Belimo FSLF24 US, on/off spring return, UL 555S listed, 24 Vac
O / S
End switch: O = no end switch | S = end switch included (per smoke control system design)
PO / PC
Fail-safe action — confirmed by fire protection engineer in writing. Do not assume.
-H
Optional: 10% heat bypass. Confirm with fire protection engineer before specifying on smoke damper applications.
Key Specs
Sizes
6", 8", 10", 12", 14", 16", 18", 20"
Actuator
Belimo FSLF24 US
Listing
UL 555S — Smoke Damper Actuator
Supply Voltage
24 Vac
Control Type
On/Off spring return
Action
PO or PC — fire protection engineer only
End Switch
Optional (S prefix) — per system design
Heat Bypass
Optional (−H) — confirm with engineer
Relay
Not available on FSLF24 US
Not a Substitute For
HAC-40 (TFB24) on smoke applications — TFB24 not listed
Warranty
2-yr electrical / 10-yr mechanical
Common Questions from the Counter
Answers to what comes up most when specifying the HAC-90.
Can I use the TFB24 (HAC-40) instead of the FSLF24 US to save cost?
No. The TFB24 is not UL 555S listed and does not meet the torque, actuation speed, elevated temperature performance, or construction requirements for smoke damper service. Substituting TFB24 for FSLF24 US on a code-required smoke damper application will not pass inspection. The AHJ will require replacement with a listed actuator. The cost of replacement — actuator cost, labour, project delay, and potential re-inspection fee — substantially exceeds the price premium of specifying the HAC-90 correctly the first time. Do not make this substitution.
Who specifies the action code — PO or PC?
The fire protection engineer specifies the action code based on the smoke control sequence of operations for the building. This is not a field decision and not a default. Different locations in the same smoke control system may require different action codes depending on whether the damper's role is to open or close on a fire signal. Get the action code from the fire protection engineer in writing before placing the order.
What's the difference between UL 555 and UL 555S?
UL 555 is the standard for fire dampers — dampers designed to close and maintain a fire barrier during a fire. UL 555S is the standard for smoke dampers — dampers designed to control smoke movement and typically operated by the smoke control system. Some applications require combination fire/smoke dampers that must meet both UL 555 and UL 555S. The FSLF24 US is listed to UL 555S for smoke damper applications. For combination fire/smoke damper applications, confirm the required listings with the fire protection engineer.
Can I replace just the FSLF24 US actuator if it fails?
Yes — the Belimo FSLF24 US is available through Belimo distributors. The actuator mounts to the HAC damper body and is field-replaceable. After replacement, the smoke damper system must be re-commissioned and the actuator replacement documented per the building's smoke control system maintenance requirements. Confirm maintenance documentation requirements with the building owner and fire alarm system contractor.
Is there a line-voltage version of this product?
Yes — the HAC-80 (Belimo FSLF120 US) uses the same UL 555S listed fire and smoke actuator at 120 Vac for applications where only line voltage is available at the damper location. Same listing, same life-safety requirements, different supply voltage.
Ready to Order
HAC-90 — Belimo FSLF24 Fire/Smoke Damper
UL 555S listed. Action code must be confirmed in writing by a fire protection engineer before ordering — then add to cart.
Configure & Order →
Size · Action Code · Engineer Sign-Off
Need help specifying the HAC-90?
Technical support available through your Hoyme wholesaler or direct.