OLMO Sierra 18,000 BTU 2-Zone 12k+12k Wall Mount, 230V, R454B - Ductless Mini Split Air Conditioner Heat Pump | No Kit No Kit

OLMO5-Yr Warranty

OS-RMS18-230VOM12SRWM12SRW-NO/NO
Product specifications
Brand Olmo
Voltage 230V
SEER 21
WiFi Included
Zone Dual Zone
Type Wall Mount
Freon R454B
Compressor Inverter
$1,702.50 $1,532.25 Save 10%
Shipping Policy calculated at checkout.
12,000 Installation Kit: No Installation Kit
12,000 Installation Kit (2): No Installation Kit
Total BTU — combined coverage
✓ Selected18,000 BTUup to 850 ft²$1,702.50$1,532.25-10%27,000 BTUup to 1,300 ft²$2,229.00$2,006.10-10%

Pickup available at 3550 Northwest 113th Court

Usually ready in 2-4 days

Questions about this system?

Answers in seconds — tap a question below

  • Covers about 500–800 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 18,000 BTU (1.5-ton)). Want help splitting the zones? Our team can map it out.
  • 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 18,000 BTU (1.5-ton). BTU tells you the capacity; SEER2 tells you the efficiency.
  • 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.
  • Rated SEER2 21.0 — a strong efficiency number, and the higher it is the lower your energy bills. Its inverter compressor ramps up and down instead of cycling on/off, so it holds the temperature steadily, runs quietly, and uses less power than a standard AC or window unit.
  • 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.
  • Yes — a big upgrade. It's far more efficient (inverter, SEER2 21.0) 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.
  • 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.
  • 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.
  • 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.
  • Ships as a complete set: OS-RMS18-230VO, OS-RM12SW-230VI, OS-RM12SW-230VI. Everything arrives together — check the photos and specs for the full kit.
  • 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.
  • 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.
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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 2-Zone System

Heat or cool 2 rooms independently from one 18000 BTU outdoor unit (12K+12K) — every zone sets its own temperature, delivered by wall mount indoor units.

Inverter Efficiency — SEER2 21

A variable-speed inverter compressor ramps to match the load instead of cycling on/off, holding SEER2 21 on 230V — steady comfort with noticeably lower energy bills.

Right-Sized Coverage

Engineered to heat & cool up to 500–800 sq ft across 2 zones — matched capacity so you never over- or under-size the space.

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.

White multi-zone sierra air conditioner with shield logo and checkmark.

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
White wall-mounted air conditioner with sleek design and modern aesthetic.

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, a 16ft Line Set, and a Smartkit (WIFI). We've meticulously thought of every detail to provide you with all the essentials for your installation.

Technical Specifications

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

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.

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Frequently Asked Questions

What size mini split do I need for my space?

For spaces up to 850 sq ft, the Olmo 2 Zone 18,000 BTU mini split is an excellent choice. This unit provides sufficient cooling and heating capacity to maintain comfort in medium to large rooms.

Can I install a mini split myself?

While some homeowners may attempt a DIY installation, the Olmo mini split system, with its 18,000 BTU capacity and 230V voltage requirement, is best installed by a professional. Proper installation is crucial for optimal performance and efficiency.

Does the mini split come pre-charged with refrigerant?

Yes, the Olmo mini split system comes pre-charged with R454B refrigerant for up to 25 ft of line set. This feature simplifies installation, as you won’t need to worry about charging it yourself.

What warranty does the Olmo mini split offer?

The Olmo mini split system is backed by a 5-year parts and compressor warranty. This ensures you have peace of mind when investing in your heating and cooling solution.

What is the SEER rating of the Olmo mini split, and is it efficient?

The Olmo 2 Zone mini split boasts a SEER rating of 21.0, making it highly efficient for energy savings. This rating means you can expect lower energy bills while enjoying optimal comfort.

What voltage does the Olmo mini split require?

The Olmo 2 Zone mini split operates on a 230V voltage supply. Make sure your electrical system can accommodate this requirement to ensure proper function of the unit.