This is a Carrier Performance Series slim-duct indoor unit only — the 24K size, model 45MBDAQ24XH3. It's built for homeowners or installers adding concealed, ducted comfort to a room or zone where a wall-mounted head or ceiling cassette isn't the right look, and it must be matched to a compatible Carrier outdoor unit to operate.
The 45MBDAQ24XH3 is Carrier's Performance Series 24K concealed slim-duct indoor unit, engineered for installation above a ceiling or below a floor and connected to supply/return ductwork. It runs on Puron Advance (R-454B) refrigerant and is designed to pair with Carrier single-zone and multi-zone outdoor condensers per AHRI-matched combinations. Note: If you would like to review the manufacturer Product Specifications, Warranty, Brochure, etc., for this system, please refer to the "Resources (System Manuals and Warranty)" Tab above on this page.
System Components
- Indoor Unit: Carrier 45MBDAQ24XH3 — 24K slim-duct concealed indoor unit (this listing)
- Outdoor Unit: NOT included — requires a matched Carrier outdoor condenser (sold separately)
- Remote: Wireless temperature-sensing handheld remote (included with indoor unit per manufacturer data)
Installation Requirements & Accessories
- Voltage: 208/230V; 1Ph; 60Hz (per manufacturer power supply data — confirm against your matched outdoor unit)
- Refrigerant: R-454B (Puron Advance), ESTER OIL
- Liquid line: 3/8 in (9.52mm); Suction line: 5/8 in (15.9mm) — for the 24K size pairing shown in manufacturer data
- Line Set Sold Separately — not included with this indoor unit
- Outdoor condenser unit sold separately — must be an AHRI-matched pairing
- Wall/ceiling grille, mounting sleeve, and duct transitions NOT included
- Professional installation required — R-454B is an A2L mildly flammable refrigerant subject to EPA Section 608 handling requirements
- Not compatible with standalone operation — this indoor unit will not run without a matched outdoor unit
Pro-Installer Tip
Flare connections on Puron Advance (R-454B) systems demand full attention to torque specification — an under-torqued or scored flare on the 3/8 in liquid or 5/8 in suction line is the single most common cause of refrigerant loss and a nuisance communication fault down the road. Use a calibrated digital torque wrench matched to the flare nut size rather than "feel," and always use 14/4 stranded wire for the indoor/outdoor communication and power run. Because R-454B is an EPA Section 608-regulated A2L refrigerant, only a licensed technician with current 608 certification should braze, evacuate, or charge this line set — this is not a self-install component.
Key Benefits
- Concealed installation — no visible indoor head, fits above ceiling or below floor with ductwork
- Four fan-speed options for airflow control across the connected duct run
- Sound levels as low as 22 dBA (manufacturer-published low end across the 45MBDA family)
- Compatible with both single-zone and multi-zone Carrier ductless outdoor systems
- Puron Advance (R-454B) refrigerant — lower global warming potential than older refrigerants, non-ozone-depleting
- Wireless temperature-sensing remote for direct comfort control
Technical Table
| Spec | Value | Unit |
|---|---|---|
| Model | 45MBDAQ24XH3 | — |
| Component Role | Indoor Slim-Duct Unit Only | — |
| Cooling Rated Capacity (DOE A2 - 95°F) | 24000 | BTU/h |
| Heating Rated Capacity (DOE H12 - 47°F) | 26000 | BTU/h |
| Power Supply | 208/230; 1; 60 | V;Ph;Hz |
| Refrigerant Type | R-454B (Puron Advance) | — |
| Refrigerant Oil | ESTER OIL | — |
| Liquid Pipe Size | 3/8 (9.52) | in (mm) |
| Suction Pipe Size | 5/8 (15.9) | in (mm) |
| Sound Level (family low end) | 22 | dBA |
| Fan Speeds | 4 | — |
| SEER2 / HSPF2 / EER2 | Dependent on paired outdoor unit | — |
| DIY Status | No — Professional Installation Required | — |
| Operating Temperature Range (Cooling) | [NEEDS VERIFICATION] | — |
| Breaker Size / MCA / MOP | [NEEDS VERIFICATION] | — |
Note: See "Resources (System Manuals and Warranty)" Tab above for full specifications.
Compatibility & Fitment
- Fits: Carrier 45MBDA family slim-duct installations designed for above-ceiling or underfloor concealed ductwork
- Requires an AHRI-matched Carrier outdoor unit — SEER2/HSPF2/EER2 performance is determined by that pairing, not the indoor unit alone
- Voltage: 208/230V; 1Ph; 60Hz — confirm your electrical circuit matches before ordering
- NOT a ceiling cassette or wall-mounted head — this is a concealed duct unit requiring ductwork and a plenum
- NOT compatible with 115V-only circuits
- Line set, outdoor condenser, grille, and mounting sleeve are NOT included with this listing
- Not a complete "system" — this SKU is the indoor unit component only
FAQ
Is professional installation required to keep the warranty valid, or is this a true DIY kit?
This is not a DIY kit. The 45MBDAQ24XH3 uses R-454B refrigerant (an A2L classification) and requires professional installation by a licensed HVAC technician to maintain the manufacturer warranty.
Is the line set included, and if not, what size do I need to buy?
The line set is sold separately. For the 24K size, the manufacturer data lists a 3/8 in (9.52mm) liquid line and a 5/8 in (15.9mm) suction line — confirm against your specific outdoor unit pairing before ordering.
Will the ceiling cassette fit between standard 16-inch on-center joists?
This is not a ceiling cassette — it is a concealed slim-duct unit designed for above-ceiling or underfloor installation with ductwork. Joist-bay fitment for cassette-style heads does not apply to this model.
Does this system work in cold climates (low-ambient heating)?
Low-ambient heating performance depends entirely on the outdoor unit this indoor unit is paired with. [NEEDS VERIFICATION] for this exact indoor/outdoor combination — check the outdoor unit's published heating capacity at 5°F and 17°F before purchase.
What breaker size do I need for this system?
Breaker sizing depends on the paired outdoor unit's MCA/MOP rating, not the indoor unit alone. [NEEDS VERIFICATION] — refer to the outdoor unit's nameplate and the system's Resources tab for exact circuit requirements.
Compliance & Warranty
Installation by a licensed HVAC professional is required to maintain warranty. This unit uses R-454B (A2L) refrigerant, which is subject to EPA Section 608 handling and certification requirements for anyone brazing, evacuating, or charging the system. Under Carrier's Consumer Choice Warranty, upon timely registration eligible equipment qualifies for either a 10-year parts-only limited warranty or a 5-year parts plus 3-year labor limited warranty. Confirm exact registration terms and eligibility in the manufacturer documentation referenced in the Resources tab.
