OLMO Sierra 42,000 BTU 3-Zone 12k+18k+18k Wall Mount, 230V, R454B - Ductless Mini Split Air Conditioner Heat Pump | No Kit No Kit No Kit
OLMO5-Yr Warranty
Product specifications
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| Voltage | |
| WiFi | |
| Zone | |
| Freon | |
| Compressor |
Please note that all delivery dates and estimated transit times are approximate and are not guaranteed. Delivery times may vary due to carrier delays, weather, holidays, peak shipping periods, or other circumstances beyond our control. How delivery dates are calculated
Pickup currently unavailable at Medley Warehouse
Questions about this system?
Answers in seconds — tap a question below
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Covers about 1800–2400 sq ft total, split across its indoor units — each head handles its own room, so you put the right capacity where you need it. Rule of thumb: ~20 BTU per sq ft, and 12,000 BTU = 1 ton (this system is 42,000 BTU (3.5-ton)). Want help splitting the zones? Our team can map it out.
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12,000 BTU = 1 ton — "tons" is just the older way of stating capacity. So 24,000 BTU = 2 tons, 36,000 = 3 tons, and so on. This system is 42,000 BTU (3.5-ton). BTU tells you the capacity; SEER2 tells you the efficiency.
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It uses R454B — the newest low-GWP eco refrigerant, so it's future-proof and efficient. The outdoor unit ships pre-charged for a standard line set, so most installs need no extra refrigerant; your licensed, EPA-608-certified installer verifies the charge and tops it off if your line set is longer.
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Needs a dedicated 230V circuit, like a large household appliance, so it can deliver full capacity to larger rooms and multi-zone setups. Your licensed HVAC installer or electrician sets up the correct breaker and disconnect to meet local electrical code.
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Yes — a big upgrade. It's far more efficient (inverter compressor) and much quieter, since the compressor sits outside instead of in your window or on the floor. It mounts permanently, doesn't block a window, and heats as well as cools year-round. Higher upfront cost, but lower bills and a longer lifespan.
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Yes to all three. It's an inverter heat pump — cools in summer, heats in winter (even in the cold), far more efficiently than electric heaters. A Dry mode also pulls out humidity, so rooms feel cooler and less muggy.
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Yes. Each indoor unit has its own remote/thermostat — set different temperatures or turn one off, so you only condition the rooms you use and save energy on the ones you're not. One outdoor unit powers them all, keeping install and running costs lower than separate systems per room.
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Yes — WiFi is included, so you can set schedules, change the temperature, and even turn it on before you get home, all from the mobile app (and pair it with voice assistants). A standard remote is included too.
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Ships as a complete set: OS-RMS42-230VO, OS-RM12SW-230VI, OS-RM18SW-230VI, OS-RM18SW-230VI. Everything arrives together — check the photos and specs for the full kit.
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It should be installed by a licensed, EPA-608-certified HVAC professional — we don't recommend DIY installation. Handling refrigerant requires EPA Section 608 certification under U.S. law, and professional installation keeps the system safe, code-compliant, and your manufacturer warranty valid.
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Yes — you get full inverter heat-pump technology and the same core features as premium brands without paying for the name, which is how we keep prices low. Shipping is free on U.S. orders over $300, and our team can help with sizing and support.
Why buy this mini split from MiniSplitsForLess
- Free Shipping over $300Ships free to the lower 48 states — flat rate, no surprises at checkout.
- USA-Based Expert SupportReal U.S. HVAC pros help with BTU sizing, refrigerant and install questions.
- Genuine Units & Full WarrantyBrand-new, authorized-dealer equipment backed by the full manufacturer warranty.
- Fast Nationwide ShippingIn stock and ready to ship from U.S. warehouses across all 48 states.
What Stands Out
Complete 3-Zone System
Heat or cool 3 rooms independently from one 42000 BTU outdoor unit (12K+18K+18K) — every zone sets its own temperature, delivered by wall mount indoor units.
Right-Sized Coverage
Engineered to heat & cool up to 1800–2400 sq ft across 3 zones — matched capacity so you never over- or under-size the space.
Year-Round Heat Pump
One system that cools in summer and heats in winter — reliable Olmo performance in every season.
Sierra Wall Mount
OLMO's Multi-Zone Sierra Series is a versatile HVAC solution that provides efficient heating and cooling for multiple rooms, featuring advanced inverter technology for precise temperature control and significant energy savings. Using eco-friendly R410A refrigerant, the system delivers reliable performance with minimal environmental impact. Ideal for both residential and commercial applications, the Sierra Series combines quiet operation, flexible installation, and user-friendly controls, making it a perfect choice for maintaining year-round comfort across multiple zones with one efficient system.
Warranty and Tech Support Info
By selecting OLMO products for your home or business, you’ll receive expert technical support from heating and cooling specialist, including access to product manuals, troubleshooting guides and warranty information.
The manufacturer provides a Limited Warranty of 5 years for the compressor and 2 years for parts.
Warranty terms
Main Features
OLMO's Multi-Zone Sierra Series delivers efficient multi-room comfort with advanced inverter technology for precise temperature control. Its eco-friendly R454B refrigerant reduces environmental impact, while quiet operation ensures minimal disruption. With flexible installation options, sleek design, and reliable heating and cooling, it’s the perfect solution for modern multi-zone climate control needs.
All Accessories Included
With your purchase, you receive a comprehensive MiniSplit system. MiniSplits4Less ensures you have everything needed for a seamless installation. Your package includes an Indoor Unit, Outdoor Unit, Remote Control, Manuals, optional LineSet, and a Smartkit (WIFI). We've meticulously thought of every detail to provide you with all the essentials for your installation.
Technical Specifications
Outdoor Unit Specs
| Model | OS-RMS42-230VO |
|---|---|
| Net/Gross Weight | 172/194 lb |
| Power Supply | 208-230V, 1Ph, 60Hz |
| Maximum Fuse Size | 60 A |
| Min. Circuit Ampacity | 36 A |
System Specs
| Cooling Capacity | 42,000 BTU |
|---|---|
| Zones | 3 |
| Voltage | 230V |
| Refrigerant Type | R454B |
| Compressor | Inverter |
| WiFi | Included |
Series Comparison Table
Technical specifications for every model in the Sierra series — this product is one of them.
| Indoor Models | OS-RM09SW-230VI | OS-RM12SW-230VI | OS-RM18SW-230VI | OS-RM24SW-230VI |
|---|---|---|---|---|
| Power Supply (V-Ph-Hz) | 208/230V-1Ph-60 | 208/230V-1Ph-60 | 208/230V-1Ph-60 | 208/230V-1Ph-60 |
| Cooling Capacity (Btu/h) | 9000 | 12000 | 18000 | 23400 |
| Heating Rated Capacity (Btu/h) | 9500 | 13000 | 19000 | 26000 |
| Output Power (W) | 25 | 25 | 35 | 35 |
| Rated Current (A) | 0.11 | 0.11 | 0.17 | 0.17 |
| Indoor Air Flow (CFM) | 341 | 365 | 647 | 706 |
| Indoor Noise Level (Hi/Mi/Lo) (dB(A)) | 39/35/30 | 39/35/30 | 45/41/37 | 47/45/42 |
| Net Dimensions (WxHxD) (in) | 32.02x10.75x8.13 | 37.38x10.75x8.13 | 48x12.63x9.25 | 48x12.63x9.25 |
| Packing (WxHxD) (in) | 39.38x13.19x6.38 | 39.38x13.19x6.38 | 51.75x15.44x12.50 | 51.75x15.44x12.50 |
| Net/Gross Weight (lbs) | 19.84 / 24.25 | 19.84 / 24.25 | 31.97 / 37.48 | 31.97 / 37.48 |
| Refrigerant Piping (Liquid Side / Gas Side) (in) | 1/4" / 3/8" | 1/4" / 3/8" | 1/4" / 1/2" | 3/8" / 5/8" |
| Outdoor Models | OS-RMS18-230VO | OS-RMS24-230VO | OS-RMS36-230VO | OS-RMS42-230VO |
|---|---|---|---|---|
| Power Supply (V-Ph-Hz) | 208/230V-1Ph-60 | 208/230V-1Ph-60 | 208/230V-1Ph-60 | 208/230V-1Ph-60 |
| Cooling Capacity (Btu/h) | 18000 | 27000 | 36000 | 42000 |
| EER2 | 13.33 | 12.85 | 12.85 | 12.0 |
| SEER2 | 22.0 | 23.0 | 22.0 | 22.0 |
| Heating Rated Capacity (Btu/h) | 18000 | 27000 | 36000 | 36000 |
| HSPF2 | 10.0 | 10.0 | 10.0 | 9.5 |
| COP2 (W/W) | 3.82 | 3.60 | 3.91 | 3.60 |
| Max Fuse (A) | 30 | 40 | 50 | 60 |
| Outdoor Air Flow (Hi) (CFM) | 1850 | 3357 | 3357 | 3357 |
| Outdoor Side Noise Level (dB(A)) | 55 | 62 | 64 | 64 |
| Dimensions (WxHxD) (in) | 33.88x26.38x12.25 | 38.38x32.88x14.12 | 38.38x32.88x14.12 | 38.38x32.88x14.12 |
| Outdoor Unit Packing (WxHxD) (in) | 39x28.75x17.75 | 43.75x37.75x18.12 | 43.75x37.75x18.12 | 43.75x37.75x18.12 |
| Net/Gross Weight (lbs) | 101.4/112.4 | 160.6/183.2 | 169.8/191.8 | 172/194 |
| Refrigerant Type/Quantity (oz) | R454B/51.15 | R454B/76.2 | R454B/105.8 | R454B/105.8 |
| Refrigerant Piping (Liquid Side / Gas Side) (in) | 1/4" / 3/8" | 1/4" / 3/8" | 1/4" / 3/8" | 1/4" / 3/8" |
| Max Refrigerant Pipe Length Each/Total (ft) | 82/164 | 82/230 | 82/230 | 82/262 |
| Ambient Outdoor (Cooling) (°F) | 5~125 | 5~125 | 5~125 | 5~125 |
| Ambient Outdoor (Heating) (°F) | -13~75 | -13~75 | -13~75 | 4~75 |
What’s Included
| Outdoor condenser | OS-RMS42-230VO |
|---|---|
| Indoor unit | OS-RM12SW-230VI |
| Indoor unit | OS-RM18SW-230VI |
| Indoor unit | OS-RM18SW-230VI |
Installation kit is not included in the selected option — pick 16ft, 25ft or 50ft above to add one.
Shipping & Returns
- Free shipping on every order over $300.
- Delivery estimate for your ZIP is shown in the buy box above.
- Returns accepted per our policy — unopened units in original packaging.
Warranty
5-year manufacturer warranty
- Limited manufacturer warranty on the compressor and sealed system components.
- Your order number is the proof of purchase — keep it for any claim.
Multiple Control Methods
Olmo’s Multi-Zone Sierra Series can be managed with a user-friendly remote control and the. This options offer precise temperature adjustments and optimal climate control for ultimate convenience.
Frequently Asked Questions
What size mini split do I need for my home?
To determine the appropriate size mini split for your space, consider that the Olmo 3 Zone 42,000 BTU system can effectively cover multiple rooms with varying square footage. Ideally, you should allocate 12,000 BTU for a small room and 18,000 BTU for larger spaces to ensure optimal cooling and heating.
Can I install a mini split myself?
While some homeowners may attempt a DIY installation, it's recommended to hire a professional for the Olmo 3 Zone 42,000 BTU system to ensure proper setup, especially given its use of R454B refrigerant. Additionally, the installation can be complex due to the included options for line sets ranging from 16ft to 50ft.
Does the mini split come pre-charged with refrigerant?
Yes, the Olmo 3 Zone 42,000 BTU mini split system is pre-charged with R454B refrigerant for up to 25 ft of line set, making installation more straightforward. However, if your line set exceeds this length, additional refrigerant may be required.
What voltage does the Olmo mini split require?
The Olmo 3 Zone 42,000 BTU mini split operates on a 230V power supply, making it compatible with standard residential electrical systems. Ensure your electrical setup meets this requirement for optimal performance.
What warranty does the Olmo mini split offer?
The Olmo 3 Zone 42,000 BTU mini split comes with a comprehensive 5-year parts and compressor warranty. This warranty provides peace of mind and coverage for essential components over an extended period.
What is the SEER rating of the Olmo mini split, and is it efficient?
The Olmo 3 Zone 42,000 BTU mini split boasts a SEER rating of 21+, which signifies excellent energy efficiency. A higher SEER rating means lower energy bills and reduced environmental impact, making it a smart choice for both heating and cooling.
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