Line Voltage · Floating Point · PO Only
HAC-70
HAC-70
Belimo LMX120-3
Inline Damper
3-Wire Open / Stop / Close · 100–230 Vac · Power Open Only · 6"–20"
✓Line-voltage floating point — 100–230 Vac, no step-down transformer needed
✓Power Open configuration only — Power Close not available on LMX120-3
✓No spring return — holds last blade position on power loss
✓Lower torque class — suited to smaller and mid-range duct sizes
✓End switch available on all sizes
✓Heat bypass (−H) available on all sizes
✓Factory-mounted Belimo LMX120-3 — ships ready to install
Is this the right product?
✔ Right product if
Your DDC controller has 3-wire floating point outputs at line voltage (100–230 Vac) and Power Open is the required action configuration.
✗ Not this product if
Power Close required at line voltage → use HAC-35 (CMB120-3) — PO and PC available.
24 Vac floating point → use HAC-34 or HAC-30
Spring return required → use HAC-44 (TFB120) for line-voltage on/off with spring return
24 Vac floating point → use HAC-34 or HAC-30
Spring return required → use HAC-44 (TFB120) for line-voltage on/off with spring return
What It Does
Line-voltage 3-wire floating point. Power Open only. Holds last position on power loss.
The HAC-70 pairs Hoyme's inline damper body with the Belimo LMX120-3 3-wire floating point actuator. Same Open / Stop / Close architecture as the HAC-35 (CMB120-3), HAC-34 (CMB24-3-T), and HAC-30 (LMB24-3-T). Same holds-last-position behavior on power loss. Three constraints distinguish the HAC-70 from the rest of the floating point family: Power Open configuration only, line voltage supply (100–230 Vac), and lower torque class than the CMB120-3 used in the HAC-35.
3-Wire Control — How It Works
OPEN
Energized → blade moves toward open while wire is energized
CLOSE
Energized → blade moves toward closed while wire is energized
STOP
Neither energized → blade holds current position
LMX120-3 vs. CMB120-3 — The Complete Line-Voltage Floating Point Decision
Two products cover line-voltage floating point. PO vs. PC availability is the determining factor.
| Spec | HAC-70 (LMX120-3) — this product | HAC-35 (CMB120-3) |
|---|---|---|
| Supply Voltage | 100–230 Vac | 100–230 Vac |
| Control Architecture | 3-wire floating point | 3-wire floating point |
| On Power Loss | Holds last position | Holds last position |
| Torque Class | Lower — smaller/mid-range sizes | Higher |
| Action Available | Power Open ONLY | Power Open AND Power Close |
| Heat Bypass (−H) | Available | Available |
| End Switch | Available | Available |
| Choose When | PO required; lower torque sufficient; spec is actuator-neutral or names LMX120-3 | PO or PC required; higher torque needed; spec names CMB120-3 |
Complete Line-Voltage HAC Floating Point Context
All four floating point variants — select by voltage and torque.
Configuration Guide
All variants are Power Open. Select size, end switch, and heat bypass.
| Variant Code | Action | End Switch | Heat Bypass | Part Number Example (10") |
|---|---|---|---|---|
| OPP | Power Open only | No | No bypass | HAC-1070-OPP |
| OPP-H | Power Open only | No | 10% bypass | HAC-1070-OPP-H |
| SPP | Power Open only | Yes | No bypass | HAC-1070-SPP |
| SPP-H | Power Open only | Yes | 10% bypass | HAC-1070-SPP-H |
−H Heat Bypass — Hot Air Zone Control Only: The −H bypass is permanent and cannot be disabled. Do not specify −H on fresh air intake, make-up air, or ventilation applications — the bypass allows continuous outdoor air infiltration when the damper is at minimum position. Specify −H only on hot air supply duct zone control applications.
Part Number Decoder
HAC-1670-SPP
HAC
Product family: universal inline air control damper
16
Size (2-digit): 06=6", 08=8", 10=10", 12=12", 14=14", 16=16", 18=18", 20=20"
70
Motor code: Belimo LMX120-3, 3-wire floating point, 100–230 Vac, no spring return, PO only
O / S
End switch: O = no end switch | S = end switch included
PP
Floating point action code — Power Open configuration only on LMX120-3
-H
Optional: 10% heat bypass. Hot air zone control only.
Key Specs
Sizes
6", 8", 10", 12", 14", 16", 18", 20"
Actuator
Belimo LMX120-3
Supply Voltage
100–230 Vac (line voltage)
Control Wires
3-wire: Open / Stop / Close
Action
Power Open ONLY
Fail-Safe
Holds last position — no spring return
Torque Class
Lower — confirm for duct size & static pressure
End Switch
Optional (S prefix)
Heat Bypass
Optional (−H suffix)
Relay
Not available
CSA Status
Confirm with Hoyme
Warranty
2-yr electrical / 10-yr mechanical
Common Questions from the Counter
Answers to what comes up most when specifying the HAC-70.
Why is the HAC-70 Power Open only — can I get Power Close at line voltage?
The LMX120-3 actuator is available in Power Open configuration only — this is an actuator specification, not a Hoyme product decision. For Power Close action at line voltage, use the HAC-35 (CMB120-3), which is available in both PO and PC configurations at the same 100–230 Vac supply voltage. If Power Close is required, the HAC-70 cannot be used — the HAC-35 is the correct product.
What happens to the blade on power loss?
The blade holds its last position. The LMX120-3 has no spring return. If the application requires the blade to move to a defined position on power loss — to open and maintain ventilation, or to close and seal the duct — use a spring return product. For line-voltage on/off with spring return, use the HAC-44 (TFB120).
When should I use the LMX120-3 (HAC-70) instead of the CMB120-3 (HAC-35)?
When Power Open is the required action, the application is actuator-neutral or specifies LMX120-3, and the lower torque class is adequate for the duct size and static pressure. If Power Close is needed, or if the spec names CMB120-3, or if the duct size and pressure require higher torque, use the HAC-35. When in doubt between LMX and CMB on an actuator-neutral spec, the CMB's higher torque is the safer choice.
Is the heat bypass available on the HAC-70?
Yes — the −H suffix is available on all HAC-70 sizes. Specify −H only for hot air supply duct zone control on single-speed furnace systems. Do not specify −H on fresh air, make-up air, or ventilation applications — the bypass allows continuous air infiltration when the damper is at minimum position.
Ready to Order
HAC-70 — Belimo LMX120-3 Inline Damper
Power Open configuration only. Select your size, end switch (OPP/SPP), and heat bypass option — then add to cart.
Configure & Order →
Size · End Switch · Heat Bypass
Need help specifying the HAC-70?
Technical support available through your Hoyme wholesaler or direct.