Mitsubishi 15,000 BTU R454B Ceiling Cassette Heat Pump System
At 15,000 BTU/h cooling and 18,000 BTU/h heating at 47°F, the SUZ-AA15NL-U1 paired with the SLZ-AF15NL-U1 cassette is the largest capacity Mitsubishi builds on the compact 31-1/2 in. outdoor chassis. That is the practical story of this size: it delivers a quarter more cooling than the one-ton unit while still weighing 81 lb. and mounting in the same footprint, and it does so at 20.6 SEER2 with a 10.1 HSPF2. The step up shows in the airflow — 405 CFM at high fan versus 335 on the 12,000 BTU cassette — and in the gas line, which moves to 1/2 in. Both the SLP-18FAU grille and the MHK2 kumo touch wireless thermostat are included, so the package installs and commissions without a supplemental accessory order.
Is a 15,000 BTU Ceiling Cassette System the Right Size?
This capacity typically serves conditioned areas around 600 to 750 square feet, or smaller rooms carrying loads well above what their footprint suggests. It is frequently the correct pick where a one-ton unit runs at full speed through the afternoon and never quite catches up — a sunroom with three exposures, a training room that fills to capacity, a west-facing showroom, or an open bay with roll-up door infiltration. The extra 405 CFM at high fan is what gets air across a wider room from a single ceiling location.
Working out the real load still matters. Two rooms of the same size perform very differently depending on glazing, roof exposure, equipment plug load, and how many people occupy them at once. Cassettes are also sensitive to ceiling height and obstructions: beams, soffits, and tall shelving interrupt the four-way throw and can leave the far corner of a long room warm even when nominal capacity is adequate. In heating, this pairing produces 11,300 BTU/h at 17°F, so a cold-climate application should be checked against that figure rather than the 18,000 BTU rating.
Ideal for: Sunrooms and Florida rooms, showrooms, training and continuing-education rooms, larger open offices, restaurant bar areas, gyms and fitness studios, church fellowship rooms, and workshops or garages with a finished ceiling.
Need more capacity? Step up to the 18,000 BTU Mitsubishi SUZAA18NL & SLZAF18NL Ceiling Cassette System, which also extends the maximum line set run to 100 ft.
Recommended applications are general guidelines only. Actual system requirements depend on insulation, window area, ceiling height, occupancy, internal heat gain, and local design temperatures. Request free sizing assistance, contact Budget Heating, or call 813-885-7999.
What's Included
| Outdoor Heat Pump | SUZ-AA15NL-U1 — 15,000 BTU/h Inverter Heat Pump Condenser |
|---|---|
| Indoor Unit | SLZ-AF15NL-U1 Four-Way Ceiling-Recessed Cassette |
| Cassette Grille | SLP-18FAU Architectural Grille — Included |
| Controller | MHK2 kumo touch RedLink Wireless Wall Thermostat — Included |
| Application | Single-Zone Ductless Ceiling Cassette Heat Pump System |
| Refrigerant | R454B (A2L, Low GWP) |
| Cooling / Heating | 15,000 BTU/h Cooling — 18,000 BTU/h Heating at 47°F |
| Efficiency | 20.6 SEER2 / 12.0 EER2 / 10.1 HSPF2 |
| Electrical | 208/230V, Single Phase, 60 Hz — MCA 17A, MOCP 29A |
| Line Set Connections | 1/4 in. Liquid × 1/2 in. Gas, Flared |
| Maximum Line Length | 65 ft. with 40 ft. Maximum Height Difference |
| Manufacturer Warranty | 10 Years |
Two details separate this package from the smaller sizes at quoting time. First, the gas line steps from 3/8 in. to 1/2 in., so a 3/8 in. line set carried over from a 9,000 or 12,000 BTU job will not serve this system — check the ductless mini split copper line sets for the correct 1/4 in. by 1/2 in. flare pairing. Second, minimum circuit ampacity climbs to 17A, which can change the breaker and conductor sizing on a retrofit. What does not change is the grille and control question: the SLP-18FAU and MHK2 are both included, so nothing is missing when the crew opens the crate. For overhead mounting hardware, the mini split ceiling cassette hanging kit is stocked separately. Installation and A2L refrigerant handling must be performed by an EPA 608 certified technician.
Outdoor Unit & Ceiling Cassette Features
SUZ-AA15NL-U1 Outdoor Heat Pump
- 15,000 BTU/h rated cooling with a 3,600 BTU/h minimum for stable operation at light load
- 20.6 SEER2 and 12.0 EER2 — the highest seasonal rating available on the compact SUZ cabinet
- 18,000 BTU/h heating at 47°F with a 3.3 COP, rising to a 19,600 BTU/h maximum
- 11,300 BTU/h of heating capacity retained at 17°F outdoor ambient with a 2.7 COP
- Largest capacity offered in the 31-1/2 in. × 11-1/4 in. × 21-11/16 in., 81 lb. chassis
- 1/2 in. gas and 1/4 in. liquid flare connections sized for the higher mass flow of this capacity
- 49 dB(A) cooling and 51 dB(A) heating, unchanged from the 12,000 BTU unit despite more capacity
- Factory charged with 2 lb. 4 oz. of R454B, covering line sets up to 25 ft. without field addition
- MCA of 17A and MOCP of 29A on 208/230V single-phase supply
- Cooling to 23°F ambient, or 0°F with the optional wind baffle, and heating down to -4°F
SLZ-AF15NL-U1 Four-Way Ceiling Cassette
- 245, 315, and 405 CFM fan speeds — roughly 20 percent more top-end air than the 12,000 BTU cassette
- Wider effective throw from a single ceiling position, useful in long or irregularly shaped rooms
- 27 dB(A) on low speed and 39 dB(A) at high, keeping conversation-level noise in occupied spaces
- 72 airflow patterns from four independently controlled vanes, adjustable per side
- Same 22-7/16 in. square by 8-3/16 in. deep body as the smaller cassettes for a 2 ft. × 2 ft. grid
- Included SLP-18FAU grille completes the flush ceiling installation with no separate order
- Included MHK2 wireless wall thermostat with RedLink communication and programmable scheduling
- Built-in condensate lift pump with 33 in. of head for routing drainage above the ceiling
- Optional 3D i-see Sensor for occupancy-driven airflow and setback control
- 31 lb. installed weight with a washable filter serviced from below through the grille
Specifications & Manuals
Confirm the 1/2 in. gas line requirement and the 17A minimum circuit ampacity in the SUZ technical specifications before ordering line sets or sizing the circuit. The SLZ documentation covers ceiling opening dimensions, grille attachment, drain lift routing, and component identification.
Frequently Asked Questions
Why does this model use a 1/2 in. gas line when the 12,000 BTU does not?
Higher capacity means higher refrigerant mass flow. Mitsubishi steps the SUZ-AA15NL-U1 up to a 1/2 in. gas connection to keep suction line velocity and pressure drop in range. A 3/8 in. line set from a smaller job cannot be reused here.
How much more air does the 15,000 BTU cassette move?
405 CFM at high fan versus 335 CFM on the 12,000 BTU cassette, with low and medium speeds at 245 and 315 CFM. That extra throw is often the reason this size is chosen for long or wide rooms.
Is the outdoor unit physically larger than the 9,000 and 12,000 BTU models?
No. The SUZ-AA15NL-U1 uses the same 31-1/2 in. wide by 11-1/4 in. deep by 21-11/16 in. high cabinet at 81 lb. It is the highest capacity Mitsubishi offers on that compact chassis.
What electrical circuit does this system need?
208/230V single-phase, 60 Hz, with a 17A minimum circuit ampacity and 29A maximum overcurrent protection. Size conductors and the disconnect to the submittal and to local code.
Does the system come with anything to hang the cassette?
The package includes the cassette, outdoor unit, SLP-18FAU grille, and MHK2 thermostat. Suspension rods and anchors are field-supplied; a ceiling cassette hanging kit is available separately.
What heating output can I count on in a cold snap?
18,000 BTU/h at 47°F and 11,300 BTU/h at 17°F, with operation continuing down to -4°F. Size cold-climate applications against the 17°F figure rather than the nameplate rating.
SUZ Technical SpecificationsSUZ Service ManualSUZ Parts ListSUZ Installation ManualSLZ Technical SpecificationsSLZ Installation InstructionsSLZ Service ManualSLZ Parts List
