OLMO Sierra 42,000 BTU Outdoor Condenser, 230V, R410A - Mini Split Air Conditioner Heat Pump

OLMO5-Yr Warranty
Product specifications
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| Compressor | |
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| Freon |
⛔ 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.
Availability
Out of stock right now
For the next arrival, call (855) 775-4822.
— we’ll fill in your ZIP. Used only for delivery dates and pickup.
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Delivery dates are estimates
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
Questions about this system?
Answers in seconds — tap a question below
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It depends on the indoor units you connect: each one is sized for its own room, at about 22 BTU per sq ft at average conditions (a 9,000 BTU indoor unit covers a room up to about 400 sq ft). This 42,000 BTU outdoor unit is the limit for all rooms together: up to about 1,900 sq ft. For a room-by-room load calculation, ask your installer for an ACCA Manual J. Not sure? Call (855) 775-4822 and we'll confirm the right size for your space.
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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 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.
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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.
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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, 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.
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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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Ships as a complete set: OS-MSR42-230VO. 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 items over $300 within the U.S., and our team can help with sizing and support.
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.
Browse: R-410A systems · R-32 · R-454B
Why buy this mini split from MiniSplitsForLess
- Free Shipping on items 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 42000 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.
Next-Gen R410A Refrigerant
Runs on R410A, a low-GWP refrigerant aligned with current U.S. efficiency regulations — future-ready and eco-friendlier.
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.
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 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
Outdoor Unit Specs
| Model | OS-MSR42-230VO |
|---|---|
| Net/Gross Weight | 198.4/224.5 lb |
| Power Supply | 208-230V, 1Ph, 60Hz |
| Maximum Fuse Size | 50 A |
| Min. Circuit Ampacity | 35 A |
| Noise Level | 63 dB |
System Specs
| Cooling Capacity | 42,000 BTU |
|---|---|
| SEER2 | 23.4 |
| Voltage | 230V |
| Refrigerant Type | R410A |
| Compressor | Inverter |
| Heating Capacity | 42,000 BTU/h |
| Cooling Capacity Range | 42,000 BTU/h |
| COP | 3.17 |
Series Comparison Table
Technical specifications for every model in the Sierra series — this product is one of them.
| 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 |
What’s Included
| Outdoor condenser | OS-MSR42-230VO |
|---|
Installation kit is not included in the selected option — pick 16ft, 25ft or 50ft above to add one.
Shipping & Returns
- Free shipping on every item 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 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 space?
The Olmo Sierra 42,000 BTU model is designed to cover a substantial area, making it suitable for larger spaces. Depending on your specific layout and insulation, this unit can effectively cool or heat rooms of varying sizes.
Can I install the Olmo mini split myself?
While it is possible to install the Olmo Sierra ductless mini split yourself, professional installation is recommended for optimal performance. If you opt for a DIY approach, ensure you have the necessary tools and skills to handle the refrigerant lines and electrical connections safely.
Does the Olmo mini split come pre-charged with refrigerant?
Yes, the Olmo Sierra mini split comes pre-charged with R410A refrigerant for up to 25 ft of line set, simplifying installation. This feature ensures that you have the right amount of refrigerant for efficient operation right out of the box.
What voltage does the Olmo mini split require?
The Olmo Sierra unit operates on a 230V power supply, making it compatible with standard residential electrical systems in many areas. Ensure your electrical setup can accommodate this voltage for optimal performance.
What warranty does the Olmo Sierra mini split offer?
The Olmo Sierra comes with an impressive 5-year parts and compressor warranty, providing peace of mind regarding the unit's durability and reliability. This warranty covers essential components, ensuring that you are protected against manufacturing defects.
What SEER rating does the Olmo Sierra have and is it efficient?
The Olmo Sierra boasts a high SEER rating of 23.4, indicating its excellent energy efficiency. This level of efficiency can lead to lower energy bills and a reduced environmental impact when cooling or heating your space.
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