MRCOOL Olympus Multi-Zone 4th Gen — Mini Split Heat Pump System (Professional Installation)
MRCOOL Olympus 4th Generation 2-Zone Ductless Mini Split AC & Heat Pump 18000 BTU (12K+12K), Wall Mount Units, 230V
Premium performance for up to six zones with advanced inverter efficiency, SmartHVAC control, and durable Gold Fin® protection.
Overview
18000 BTU
2 Zones
25.1 SEER2
Operates to -13°F
R-454B
SmartHVAC App
Alexa & Google
Wall Mount Air Handlers
The Olympus Multi-Zone 4th Gen is built for whole-home flexibility—one outdoor condenser can support multiple indoor zones for independent room comfort. Note: multi-zone systems run in one mode at a time (the system heats or cools as a whole).
System Combination
MULTI3-18HP230C-O + 2X O-12-HP-WMAH-230C-O
MULTI3-18HP230C-O + 2X O-12-HP-WMAH-230C-O
Outdoor Model
MULTI3-18HP230C-O
MULTI3-18HP230C-O
Min Circuit Ampacity
16.0
16.0
Max Fuse / Breaker
20
20
Why Homeowners Love It
- Your comfort, multiplied: Multi-zone technology gives room-by-room temperature control in up to six zones.
- Premium efficiency: Advanced inverter performance helps reduce monthly heating and cooling costs.
- All-season reliability: Dependable low-ambient operation and stable comfort in changing outdoor conditions.
- Smart control: Set schedules, adjust setpoints, and manage zones from the SmartHVAC app (plus Alexa/Google voice).
- Built to last: Gold Fin® condenser protection improves corrosion resistance—ideal for harsh or coastal regions.
Important: This system is not marketed as DIY—professional installation is required.
What’s Included
- (1) Outdoor condenser: MULTI3-18HP230C-O
- Indoor wall mounts:
- 12,000 BTU (x2) — Model: O-12-HP-WMAH-230C-O
- Zone remotes/controllers (model-specific)
- Refrigerant line sets & interconnect/communication wiring (must be selected in the options to be included; choose the appropriate length for each indoor unit based on your layout)
- Mounting hardware for indoor units
- Installation documentation (see Documents & Downloads)
Mrcool DIY Multi-Zones
Key Features
- Advanced inverter technology: High efficiency and stable comfort with variable-speed performance.
- Low-ambient cooling: Designed for applications that may require cooling in colder weather (e.g., server rooms / greenhouses).
- Refrigerant leak detection: Built-in monitoring with fault indication to help protect the system.
- Gold Fin® condenser: Added corrosion resistance for long-term durability.
- SmartHVAC control: App scheduling + remote access, plus Alexa/Google voice integration.
- Comfort features: Sleep mode, auto restart, and diagnostic codes (model-specific).
R-454B is an A2L refrigerant. Installation/service must follow the manufacturer manual and applicable codes.
Comfort Modes
- Auto: Automatically selects heating or cooling to maintain setpoint.
- Cool / Heat: Dedicated modes for seasonal comfort.
- Dry: Dehumidifies while maintaining comfort.
- Sleep: Energy-saving overnight profile.
- Timer: Scheduled on/off for efficiency.
Multi-zone systems operate in one mode at a time—you can’t heat one room while cooling another.
Warranty
Standard coverage commonly includes a 7-year compressor warranty and a 5-year parts warranty (registration requirements apply).
Extended limited lifetime replacement coverage may require enrollment in the MRCOOL® Care Kit program and additional conditions/fees.
Indoor Specs
Indoor Unit Specifications — O-12-HP-WMAH-230C-O
| brand name | MRCOOL |
|---|---|
| series | Olympus 4th Gen Air Handlers |
| model | O-12-HP-WMAH-230C-O |
| unit type | Mini-Split |
| short description | Olympus 12,000 BTU 1 Ton Ductless Mini-Split Wall Mounted Air Handler - 230V/60Hz |
| long description | Experience dependable heating and cooling with the MRCOOL® OLYMPUS ESTAR® 12k Series air handler, designed for spaces up to 550 square feet—perfect for bedrooms, home offices, garages, and more. Its compact design makes installation quick and hassle-free for your technician. Stay in control from anywhere with the MRCOOL® Smart HVAC app, which connects via Wi-Fi to your smartphone or tablet. Prefer a more hands-on approach? Use the included remote control for simple and convenient operation. Engineered for energy efficiency, this unit delivers strong performance with a SEER2 rating of 25.5, EER2 of 13, and HSPF2-4 of 10.6—helping you reduce energy consumption and save on utility costs. A variety of indoor fan speeds ensures optimal comfort, while its whisper-quiet operation at just 46 dB keeps noise to a minimum. Now using R-454B refrigerant, an environmentally friendly option, this system supports a greener future without compromising performance. Enjoy multiple control options, including wireless remote access, the smartHVAC app, and voice control compatibility with Amazon Alexa and Google Assistant—giving you the flexibility to adjust your comfort your way. Backed by an industry-leading warranty, including a limited lifetime warranty, 7-year compressor coverage, and a 5-year parts warranty, the MRCOOL® OLYMPUS ESTAR® 12k Series offers advanced features, quiet operation, and year-round comfort you can count on. |
| works with | O-ES-12-HP-C-230C-O1 MULTI3-18HP230C-O MULTI4-27HP230C-O MULTI5-36HP230C-O MULTI6-48HP230C-O |
| tonnage | 1.0 |
| voltage (v) | 208/230 |
| phase | 1 |
| cycle (hz) | 60 |
| max fuse breaker (a) | 15 |
| min circuit ampacity (a) | 3.0 |
| mount type | Wall |
| color | White |
| max coverage area | Up to 550 |
| refrigerant type | R-454B |
| decibel rating (dba) | 47/36.5/32.5/22/19.5 |
| decibel rating low (dba) | 19.5 |
| decibel rating high (dba) | 47.0 |
| number of speeds | 5 (Variable) |
| oscillation | Yes |
| lineset fitting type | Flare |
| liquid line size | 1/4 |
| suction line size | 3/8 |
| blower motor speeds | 441.4/323.7/229.6/176.6/147.2 |
| blower motor rpm | 1100/850/700 |
| filter type | Reusable |
| auxiliary heater included | No |
| auxiliary heater available | No |
| fan only option | Yes |
| sleep mode | Yes |
| auto cool | Yes |
| wifi compatibility | Yes |
| app compatibility | Yes |
| works with ios | Yes |
| works with android | Yes |
| remote control included | Yes |
| ul listed | Yes |
| csa listed | Yes |
| etl listed | Yes |
| base warranty | 5-Year Parts |
| base parts warranty | 5-Year |
| base remote warranty | 5 Year |
| registered labor warranty | None |
| base labor warranty | None |
| has batteries | Yes |
| contains electronics | Yes |
| contains chemicals | Yes |
| contains compressed gas | Yes |
| proposition 65 warning | Yes |
| restricted states | GU, PR, VI |
| net depth (in) | 9.09 |
| net height (in) | 11.81 |
| net width (in) | 33.74 |
| net weight | 22.93 |
| gross depth (in) | 12.2 |
| gross height (in) | 14.57 |
| gross width (in) | 36.22 |
| gross weight (lbs) | 29.32 |
Manuals
- https://doxrepo.mrcool.com/mc-oly-sz-4g-im-um-en-01.pdf
- https://doxrepo.mrcool.com/mc-oly-sz-4g-sm-en-01.pdf
Submittals
Documents
Warranty
Outdoor Specs
Outdoor Unit Specifications — MULTI3-18HP230C-O
| brand name | MRCOOL |
|---|---|
| series | Olympus 4th Gen Multi-Zone Condensers |
| model | MULTI3-18HP230C-O |
| unit type | Mini-Split |
| short description | Olympus 18,000 BTU Mini-Split Condenser - 230V/60Hz |
| long description | The MRCOOL® Olympus MULTI3-18HP230C-O is a high-performance 18,000 BTU multi-zone heat pump condenser designed to power up to three indoor units simultaneously. Perfect for homeowners looking to efficiently manage temperatures in multiple spaces, this ductless system offers individualized climate control for each connected zone, making it a flexible solution for modern living environments. Built with advanced inverter technology, the unit delivers impressive efficiency, with SEER2 ratings up to 25.1 and HSPF2-4 up to 10. It performs reliably in diverse conditions, operating in outdoor temperatures as low as 5°F, ensuring comfort in both summer and winter months. This model is compatible with various MRCOOL indoor units, including wall-mounted, ceiling cassette, and concealed duct options, giving users the freedom to tailor the system to their home’s layout and aesthetics. Smart features elevate user convenience, with control options that include the MRCOOL SmartHVAC app, traditional remotes, or even voice commands via Amazon Alexa and Google Assistant. Additional functions such as sleep mode, auto restart, and refrigerant leak detection contribute to enhanced safety and comfort. Backed by a 7-year warranty on the compressor and 5 years on parts (with professional installation), the MRCOOL®Olympus MULTI3-18HP230C-O is a reliable and energy-efficient choice for those seeking customized, zone-specific heating and cooling. |
| works with | O-09-HP-WMAH-230C-O DUCT-09HP-230B-O CASSETTE09HP-230C-O O-12-HP-WMAH-230C-O DUCT-09HP-230B-O CASSETTE12HP-230C-O |
| feature list | Installation by a licensed professional required where applicable 7-Year Compresser, 5-Year Parts warranty when registered and installed by a licensed professional R-454B environmentally friendly refrigerant Energy Star Certified |
| seer2 | Up to 25.1 |
| eer2 | Up to 14 |
| hspf2-4 | 9.8 |
| hspf2-5 | 7.8 |
| tonnage | 1.5 |
| cooling capacity (btu) | 18000.0 |
| heating capacity (btu) | 19000.0 |
| voltage (v) | 208/230 |
| phase | 1 |
| cycle (hz) | 60 |
| max fuse breaker (a) | 20 |
| min circuit ampacity (a) | 16.0 |
| color | White |
| max coverage area | Up to 750 |
| zone capacity | 3.0 |
| refrigerant type | R-454B |
| refrigerant volume (oz) | 61.73 |
| decibel rating (dba) | 59.5 |
| inverter | DC |
| max lineset length (ft) | 196.8 total |
| lineset fitting type | Flare |
| compressor motor type | Twin-Rotary |
| condenser fan motor rpm | 750/600/500 |
| metering device | EXV + Capillary |
| ul listed | Yes |
| csa listed | Yes |
| etl listed | Yes |
| energy star certified | Yes |
| ahri certified | Yes |
| base warranty | 5-Year Parts/7-Year Compressor |
| base parts warranty | 5-Year |
| base compressor warranty | 7-Year |
| base remote warranty | 5 Year |
| registered labor warranty | None |
| base labor warranty | None |
| has batteries | Yes |
| contains electronics | Yes |
| contains chemicals | Yes |
| contains compressed gas | Yes |
| proposition 65 warning | Yes |
| restricted states | GU, PR, VI |
| net depth (in) | 13.46 |
| net height (in) | 26.5 |
| net width (in) | 35.04 |
| net weight | 100.53 |
| gross depth (in) | 17.24 |
| gross height (in) | 29.53 |
| gross width (in) | 40.55 |
| gross weight (lbs) | 109.35 |
Manuals
- https://doxrepo.mrcool.com/mc-oly-mz-4g-im-um-en-01.pdf
- https://doxrepo.mrcool.com/mc-oly-mz-4g-sm-en-01.pdf
Documents
Warranty
Helpful Notes
Professional installation required
Installation must be completed by a qualified HVAC professional. Improper installation can cause water leakage, electrical shock, or fire.
Mixing indoor unit types
Many Olympus multi-zone configurations allow mixing compatible indoor styles (wall mounts, ceiling cassettes, and concealed duct models). Confirm compatibility for your condenser model before ordering.
Line sets & wiring (options)
Line sets and communication wiring may be bundled depending on your selected options. If no installation kit is selected, they may not be included. Select the appropriate length for each indoor unit based on your layout.
Electrical & breaker sizing
Use MCA (16.0) and Max Fuse/Breaker (20) as starting points, then size per the installation manual and local code.
Line sizing
Indoor line sizes: 1/4 / 3/8. Confirm final line sizes, allowable lengths, and any additional charge requirements for your exact pairing before selecting line sets.
