⛔Wait! This is an Individual Component To build a working system, this unit must match your other equipment in two ways:
Same Brand Only: Only pair with other same Brand and Series.
Same Refrigerant: Both units must use the exact same gas type (R454B, R32, or R410A).
Mixing different brands or refrigerant types will cause the system to fail and void your warranty.
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Questions about this system?
Answers in seconds — tap a question below
Sized for about 500–800 sq ft. Rule of thumb: ~20 BTU per sq ft, and 12,000 BTU = 1 ton (this unit is 18,000 BTU (1.5-ton)). Ceiling height, insulation, sun and climate shift that — if you're between sizes, size up for hot/humid rooms. Not sure? We'll confirm the right BTU for your space.
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 R410A — a proven, widely serviced refrigerant. 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 23.4 — 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 23.4) 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 — WiFi is not 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-MSR18-230VO. 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.
R-410A
Hurry to buy! Get your mini-split system with R-410A refrigerant
(offer valid until November 27)
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Important info
R-410A is being phased down in favor of newer refrigerants; inventory is limited.
Existing R-410A systems remain serviceable; parts and qualified service are widely available.
Check local codes and rebates. Some incentives prioritize high-efficiency heat pumps (R-32/R-454B).
We stock both R-410A and next-gen options—choose what fits your timeline and budget.
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
Sleek Wall-Mount Design
A slim, quiet indoor head mounts high on the wall and delivers 18000 BTU of heating & cooling — modern looks with whisper-quiet operation.
Inverter Efficiency — SEER2 23.4
A variable-speed inverter compressor ramps to match the load instead of cycling on/off, holding SEER2 23.4 on 230V — steady comfort with noticeably lower energy bills.
Right-Sized Coverage
Engineered to heat & cool up to 500–800 sq ft — 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 designed to provide efficient heating and cooling for multiple rooms, equipped with advanced inverter technology for precise temperature control and significant energy savings. Using eco-friendly R410A refrigerant, the system ensures reliable performance with minimal environmental impact. Perfect for residential or commercial applications, the Sierra Series offers quiet operation, flexible installation, and user-friendly controls, making it an ideal 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.
OLMO's Multi-Zone Sierra Series delivers efficient multi-room comfort with advanced inverter technology for precise temperature control. Its eco-friendly R410A 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.
Technical Specifications
Indoor Models
OS-M09SRW-230VI
OS-M12SRW-230VI
OS-M18SRW-230VI
OS-M24SRW-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-MSR18-230VO
OS-MSR24-230VO
OS-MSR36-230VO
OS-MSR42-230VO
Power Supply V-Ph-Hz
208/230V-1Ph-60
208/230V-1Ph-60
208/230V-1Ph-60
208/230V-1Ph-60
Capacity Btu/h
18000
24000
32000
42000
Cooling
EER2 Btu/h
12.5
12.5
12.5
10.5
SEER2 Btu/h
21.0
22.0
21.0
20.0
Heating
Rated Capacity Btu/h
18000
24000
36000
42000
HSPF2 Btu/h
9.50
9.05
9.00
8.95
COP2 W/W
3.45
3.66
3.37
3.17
Minimum Circuit Ampacity A
23
25
32.2
35
Max Fuse A
30
30
50
50
Outdoor Air Flow (Hi) CFM
1850
2350
3411
3411
Outdoor Side Noise Level dB(A)
55
55
59
63
Dimensions (WxHxD) in
33.88×26.38×12.25
37.38×33×13.38
37.38×41.38×13.38
37.38×41.38×13.38
Outdoor Unit Packing (WxHxD) in
39×17.75×28.75
43.75×18.13×36.25
43.75×18.13×47.25
43.75×18.13×47.25
Net/Gross Weight lbs
116.8/125.6
158.7/169.5
188.5/220.5
198.4/224.5
Refrigerant
Refrigerant Type/Quantity oz
R410A/63.49
R410A/81.13
R410A/105.82
R410A/120
Refrigerant Precharge ft
50
75
98
98
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
66/197
66/246
66/262
Ambient Temperature
Outdoor (Cooling) °F
14~114.8
14~114.8
14~114.8
14~114.8
Outdoor (Heating) °F
-13~75.2
-13~75.2
-13~75.2
-4~75.2
Multiple Control
Methods
Olmo’s can be managed with a user-friendly remote control. 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 room?
For spaces up to 850 sq ft, the Olmo Sierra 18,000 BTU outdoor condenser is an excellent choice. This unit provides sufficient cooling and heating capacity for medium to large-sized rooms.
How much does a mini split system like the Olmo Sierra cost?
The price of the Olmo Sierra 18,000 BTU mini split system can vary based on installation kits and local labor costs. Typically, you can expect to invest in the range of $1,500 to $3,000, depending on the complexity of installation.
Can I install the Olmo mini split myself?
While it is possible to install the Olmo Sierra mini split system yourself, it requires knowledge of HVAC systems, especially since it operates on 230V. For optimal performance and warranty coverage, professional installation is recommended.
Does the Olmo Sierra mini split come pre-charged with refrigerant?
Yes, the Olmo Sierra mini split system comes pre-charged with R410A refrigerant for up to 25 ft of line set, making installation easier. Ensure that you follow the manufacturer’s guidelines during installation for optimal performance.
What is the warranty on the Olmo Sierra mini split system?
The Olmo Sierra mini split system is backed by a 5-year parts and compressor warranty, providing peace of mind for your investment. Make sure to register your product to take full advantage of the warranty coverage.
What does the SEER rating of 23.4 mean for the Olmo Sierra?
The Olmo Sierra mini split system boasts a high SEER rating of 23.4, indicating excellent energy efficiency. This means lower energy bills and a smaller carbon footprint while providing effective cooling and heating.
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