This is the indoor slim-duct (concealed duct) unit only β Carrier model 45MBDAQ48XH3, 48,000 BTU/h size class. It's built for installers and homeowners assembling a custom ducted mini split system, and it requires a matching Carrier outdoor condenser, line set, and duct accessories, all sold separately.
The 45MBDAQ48XH3 is a Carrier Performance Series concealed slim-duct indoor unit, part of the 45MBDA family, sized at 48,000 BTU/h. It is designed to sit above a ceiling or below a floor with ductwork run to one or more rooms, rather than mounting directly on a wall or in an open cassette bay. Carrier's manufacturer documentation covers ceiling, wall, and underfloor installation configurations for this platform. 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 (this listing): Carrier 45MBDAQ48XH3, 48K slim concealed-duct indoor unit, Puron Advance (R454B) refrigerant.
- Outdoor condenser: Not included with this listing β must be purchased separately and matched by Carrier's AHRI-certified pairing tables.
- Line set, grille/diffuser, mounting sleeve, and wireless remote: Not included β sold separately.
Installation Requirements & Accessories
- Voltage: 208/230V; 1-Phase; 60Hz.
- Refrigerant: R454B (A2L, mildly flammable classification) with ESTER OIL β requires EPA Section 608 certified handling.
- Line set sizing: 3/8 in (9.52 mm) liquid line, 3/4 in (19 mm) suction line β line set itself is sold separately.
- Not included: Outdoor condenser, line set, duct grille/diffuser, mounting sleeve, and remote accessories.
- Not compatible with: Any outdoor unit not listed on Carrier's AHRI-matched pairing chart for the 45MBDA family; do not treat this listing as a complete system or as a wall-mount or cassette unit.
- Professional installation required β this is not a pre-charged DIY quick-connect system.
Pro-Installer Tip
Flare connections on R454B systems demand the same discipline as R410A, but the A2L classification raises the stakes on leak prevention. Undertorqued or scored flares lead to slow refrigerant loss, which shows up later as reduced capacity or nuisance fault codes at the indoor board. Use a calibrated digital torque wrench set to the fitting manufacturer's spec, and inspect the flare surface with an eccentric flaring tool before final connection β don't reuse a flare that's been over-tightened once already. Because R454B is a mildly flammable A2L refrigerant, recovery, evacuation, and charging must be performed by an EPA Section 608 certified technician using leak-check procedures appropriate for A2L systems.
Key Benefits
- Concealed installation β ductwork routes conditioned air out of sight, above ceilings, below floors, or behind walls.
- Four fan-speed options for finer airflow control at the indoor coil.
- Rated sound level as low as 22 decibels at the indoor unit (lowest published figure for the platform).
- Compatible with Puron Advance (R454B) refrigerant, which Carrier states reduces global warming potential by 75% versus older refrigerants while remaining non-ozone-depleting.
- Works with both single-zone and multi-zone Carrier ductless outdoor systems, once matched correctly.
- Wireless, temperature-sensing handheld remote included for zone-level control.
Technical Table
| Spec | Value | Unit |
|---|---|---|
| Model | 45MBDAQ48XH3 | β |
| Family | 45MBDA | β |
| Component Role | Indoor Slim-Duct (Concealed Duct) Unit Only | β |
| Cooling Rated Capacity (DOE A2 - 95Β°F) | 48000 | Btu/h |
| Heating Rated Capacity (DOE H12 - 47Β°F) | 53000 | Btu/h |
| SEER2 / HSPF2 / EER2 | Depends on paired outdoor unit | β |
| Voltage | 208/230;1;60 | V;Ph;Hz |
| Refrigerant Type | R454B | β |
| Refrigerant Oil | ESTER OIL | β |
| Liquid Pipe Size | 3/8 (9.52) | in (mm) |
| Suction Pipe Size | 3/4 (19) | in (mm) |
| Operating Weight | 208.78 (94.7) | lb (kg) |
| Height | 52.48 (1333) | in (mm) |
| Width | 37.48 (952) | in (mm) |
| Depth | 16.34 (415) | in (mm) |
| Sound Level (Low) | 22 | dBA |
| Breaker Size (MCA/MOCP) | [NEEDS VERIFICATION] | β |
| Operating Temperature Range | [NEEDS VERIFICATION] | β |
Note: See "Resources (System Manuals and Warranty)" Tab above for full specifications.
Compatibility & Fitment
- Compatible with Carrier 45MBDA family outdoor pairings on the 208/230V; 1-Phase; 60Hz circuit only.
- Fits ceiling, wall, or underfloor duct installation configurations per Carrier's documentation for this platform.
- Not a complete system β outdoor condenser is not included and must be purchased and matched separately per Carrier's AHRI-certified combination charts.
- Not included: line set, duct grille/diffuser, mounting sleeve.
- Not a wall-mount or cassette unit β this is a concealed slim-duct chassis; do not install it in an open ceiling cassette bay.
- SEER2, HSPF2, and EER2 ratings are not assigned to this indoor unit in isolation β they are determined by the specific outdoor unit it is paired with.
FAQ
What breaker size do I need for this system?
[NEEDS VERIFICATION] β the manufacturer data provided for this indoor unit does not list a breaker size (MCA/MOCP) for 45MBDAQ48XH3. Breaker sizing depends on the paired outdoor condenser; refer to the outdoor unit's nameplate and installation instructions.
Is professional installation required to keep the warranty valid, or is this a true DIY kit?
This is not a DIY kit. It uses R-454B refrigerant and requires professional installation by a licensed HVAC technician, including proper refrigerant handling under EPA Section 608.
Is the line set included, and if not, what size do I need to buy?
The line set is not included and is sold separately. This indoor unit uses a 3/8 in (9.52 mm) liquid line and a 3/4 in (19 mm) suction line.
Will the ceiling cassette fit between standard 16-inch on-center joists?
This is a concealed slim-duct unit, not a ceiling cassette, so 16-inch joist-bay fitment does not apply. Its listed cabinet dimensions are 52.48 in height, 37.48 in width, and 16.34 in depth; confirm plenum and duct clearance with your installer.
Does this system work in cold climates (low-ambient heating)?
Cold-climate heating performance is a function of the paired outdoor unit, not this indoor coil alone. [NEEDS VERIFICATION] for this exact indoor/outdoor pairing β check the matched outdoor unit's low-ambient heating capacity data.
Compliance & Warranty
This unit uses R454B (A2L) refrigerant and must be installed, evacuated, and charged by a licensed HVAC professional certified under EPA Section 608. Installation by a licensed HVAC professional is required to maintain warranty. Carrier's Consumer Choice Warranty applies upon timely registration on eligible equipment: choose either a 10-year parts-only limited warranty or a 5-year parts plus 3-year labor limited warranty. Confirm current terms and registration requirements in the manufacturer documentation referenced above.
