If you're looking to add heating and cooling to a single room without tearing into your walls or hiring an HVAC crew, a 115V DIY mini split is the place to start, and the MRCOOL 115V DIY mini split, in its 9,000 BTU and 12,000 BTU DIY 5th Generation models, is the one most people look at first. Here's what you need to know about both: specs, sizing, installation, how to pick the right one, and how Zone Air's 115V units compare.
Quick Answer: 115V MRCOOL DIY Mini Split Options for 2026
A 115V DIY mini split usually comes in 9,000 BTU or 12,000 BTU, and MRCOOL's DIY 5th Generation has both sizes. These are single zone heat pump systems that have pre charged Quick Connect line sets, use R-454B refrigerant and run on 115V/60Hz single-phase power, so they run on a 115V circuit and you do not need 230V.
For small bedrooms, kids' rooms and home offices up to about 400 square feet, the 9,000 BTU unit is the one to look at. The 12,000 BTU unit is the one you would use for larger living rooms, bedroom suites and bonus rooms up to about 550 square feet. If you just want to control one room, a single zone system can be a good way to go.
There's a quick comparison from MRCOOL's catalog:
- 9K (DIY-09 115V): up to 400 sq ft, SEER2 23.6, HSPF2-4 11.5
- 12K (DIY-12 115V): up to 550 sq ft, SEER2 23.5, HSPF2-4 10.2, listed around $2,359 at a major home-improvement store (September 2026)
- Both are listed as ENERGY STAR V6.1, and that includes the Cold Climate label
- Both use pre charged line sets: no vacuuming, no gauges, no refrigerant handling
In the same two sizes, Zone Air also makes 115V DIY mini splits, and you can see how they compare section by section below.
MRCOOL DIY 5th Generation 115V Mini Splits Overview
The "MRCOOL DIY 5th Generation" label is the name MRCOOL uses for its current line of ductless systems that a homeowner can install.
MRCOOL DIY single zone systems range from 9,000 to 36,000 BTU, but the 9k and 12k models are the only 115V options. The 18K and up are 208/230V. These are inverter-driven ductless mini split heat pumps that can provide both heating and cooling without any ductwork.
With the core DIY features, you get a line set that is already pre charged and has Quick Connect fittings, so you don't need to use a vacuum pump or gauges. According to MRCOOL, "no special tools or training are necessary to install". However, the manual from MRCOOL says the electrical connections should be installed by a licensed electrician. Through a Wi-Fi dongle, the 5th Gen units have Wi-Fi app control, and through MRCOOL's smart thermostat they have voice control with Alexa and Google Assistant.
MRCOOL's 5th Gen uses R-454B refrigerant, and the 4th Gen that it replaces is being closed out.
MRCOOL DIY 5th Gen 9,000 BTU 115V Single Zone (DIY-09 115V)
The 9k is the entry-level 115V MRCOOL DIY mini split for a single room. It delivers 9,000 BTU of cooling and 10,000 BTU of heating, with a SEER2 of 23.6 and HSPF2-4 of 11.5 (catalog spec table). It covers up to 400 square feet, which is enough for a bedroom, office, nursery or workshop.
Each unit ships with a 25-foot pre charged line set as standard. You can buy other lengths separately. A genuine DIY system should have precharged refrigerant lines and manufacturer-approved fittings for installation. The 9k has both. Indoor noise drops as low as 18 dB(A) on the silent setting, so it won't disturb sleep or concentration.
Because the 9k uses an inverter-driven compressor, it can ramp down during mild weather rather than short cycling. But correct sizing still matters, because oversizing leads to poor humidity control and uneven temperature swings even with modulation. The 9k is listed as ENERGY STAR Cold Climate, and its high HSPF2 rating pays off most in cooler climates.
Before ordering, check your room size, insulation quality and climate zone. A sizing calculator is a quick way to confirm whether 9k is right for your space.
MRCOOL DIY 5th Gen 12,000 BTU 115V Single Zone (DIY-12 115V)
With a 12k 115V unit, you get the sweet spot for homeowners who need more capacity without upgrading to 230V power. It has 12,000 BTU of both cooling and heating, and it covers rooms up to about 550 square feet. That works for a primary bedroom suite, or a larger living room, or a basement conversion or a garage that you turned into living space.
MRCOOL got this model listed with ENERGY STAR. It uses R-454B refrigerant. Like the 9k, it comes with a 25-foot pre charged line set, so you need no vacuum pump and you do no refrigerant handling. It was listed around $2,359 at a major home-improvement store in September 2026.
When does stepping up to 230V make sense? The MRCOOL DIY 18k model covers up to 800 square feet. It needs a 208/230V circuit. If your room is under 550 square feet and your panel has room for the 115V circuit it needs, the 12k keeps the install easier and the budget lower. For this unit, MRCOOL lists a minimum circuit ampacity of 18A and a maximum fuse of 20A.
How Zone Air's 115V Units Compare
Zone Air has its own 115V DIY mini splits. They come in the same two sizes. Here's how they line up against MRCOOL's, and the Zone Air prices are as of November 2026:
- Price and coverage: the Zone Air 9K 115V is $1,899.99 and it covers up to 450 sq ft. The Zone Air 12K 115V is $1,999.99 and covers up to 600 sq ft.
- Efficiency: Zone Air's 115V units are 23 SEER2, which is slightly below MRCOOL's 23.5 and 23.6 at 115V. Zone Air's efficiency lead is at 230V. At 24 SEER2 on 230V, Zone Air is the highest-efficiency pre-charged quick-connect DIY system of the brands compared here, since MRCOOL's best single-zone is 23.6. See the spec sheets.
- Plug-in option: Zone Air's 115V models can plug into a dedicated 15A GFCI outlet with the optional 3-prong cord kit, where local electrical code allows a plug-in install (never an extension cord). MRCOOL's 115V units are hardwired.
- Line sets: a 16 ft pre-charged line set comes in the box. Of the brands compared here, Zone Air is the only one that cuts your pre-charged line set to the exact length you measure, any whole foot from 5 to 75, as of November 2026. MRCOOL sends fixed 11.5, 16, 25, 35 and 50 ft sets plus couplers and has you coil the excess. With a single factory-sealed run up to 75 ft and no field joint, Zone Air's longer sets are different from how MRCOOL connects two sets with a coupler beyond 50 ft.
- Cold and heat: Zone Air is rated to heat down to −13°F, the same floor as MRCOOL's standard DIY 5th Gen. Higher-tier MRCOOL DIY models are rated lower. With an outdoor cooling rating up to 131°F, Zone Air tops the 122°F that MRCOOL publishes.
- Warranty and returns: 5-year parts and 7-year compressor coverage with no registration deadline, and installing it yourself does not void it. Zone Air sells direct, with 30-day returns on uninstalled units and free shipping to the lower 48, 1–2 days to process and 2–5 in transit.
- More rooms later: for whole-home setups, Zone Air is the only DIY mini split that lets you mix wall-mount, ceiling cassette and concealed ducted units on one outdoor unit (as of November 2026). You can build a 2- or 3-zone system here.
Zone Air units get final assembly, testing, and inspection in the USA, from globally-sourced components, and come with live technical support 8 AM–6 PM MT.
MRCOOL 5th Gen DIY Pre-Charged Lines, R-454B and Smart Controls
Three features define the MRCOOL 5th generation.
Pre Charged Quick Connect Line Sets. The line set arrives factory-charged with R-454B and sealed. You connect, tighten to spec and open the valves: no vacuuming, no gauges, no hiring an HVAC technician for the refrigerant side. Pre-charged lines in DIY systems eliminate the need for HVAC technicians during installation.
R-454B Refrigerant. R-454B has a much lower global warming potential than R-410A and is replacing R-410A in new systems. It's an A2L mildly flammable refrigerant, so check the manual and local codes for any minimum room size or ventilation requirements.
Smart Comfort Controls. MRCOOL's 5th Gen units have smartphone app control over Wi-Fi, with Alexa and Google Assistant through its smart thermostat. Features include variable fan speeds, Follow Me temperature sensing, timers and auto/dry modes. These add up to year round comfort and long-term energy savings. For whole home climate management, MRCOOL's DIY multi zone condensers run up to 6 indoor units.
9K vs 12K 115V DIY Mini Split in 2026
Which capacity you need comes down to a few factors that are practical to think about.
- Square footage: MRCOOL's 9k can handle up to 400 sq ft and its 12k can handle up to 550 sq ft (Zone Air's 450 and 600).
- Ceiling height: Rooms with ceilings that are 9-foot or higher need more BTU for each square foot.
- Insulation quality: Poorly insulated spaces push you toward the higher capacity.
- Climate zone: In colder regions, how the mini split does in cold weather matters a lot if you plan to use it as your main way to heat the home. MRCOOL's 5th Gen DIY systems can run in heating mode down to about −13°F (manual operating range), though the amount of heat they put out drops as the temperature gets colder.
Scenario examples:
- A 12×12 bedroom (~144 sq ft) in a mild climate with good insulation: the 9k is more than enough and it runs at a higher level of efficiency.
- A 20×22 living room (~440 sq ft) in a colder region with high ceilings: the 12k is the better choice, since the 9k would run near capacity too much of the time.
- A 500 sq ft garage conversion in a cold climate: the 12k is the minimum. Extremely harsh winters may call for a 230V cold-climate model.
Electrical considerations: a 115V mini split needs its own dedicated circuit. If your home has limited panel capacity, 115V lets you skip a 230V circuit upgrade, which makes the install faster and cheaper.
Installing a 115V MRCOOL DIY Mini Split
This is a high-level walk-through. Always follow the official MRCOOL install manual for your specific unit. Here's the general order of work.
- Plan and mount the bracket for the indoor air handler, making sure there is proper clearance on all sides
- Drill the core hole through the wall so the line set and the condensate drain can pass through
- Place the outdoor condenser on a pad or mount it on a wall
- Route the pre charged line set and connect it with Quick Connect fittings
- Set up condensate drainage
MRCOOL's manual says the electrical work has to be done by a licensed electrician. That covers the breaker, the whip, the disconnect and the final connections.
Common accessories to plan for:
- Condenser mounting pad or wall bracket
- A cover for the line set so the outside of your home looks clean
- Exterior-grade disconnect switch
- Surge protection
Quick Connect fittings must be tightened to the torque values in the manual. Under-tightened fittings leak, and over-tightened ones can be damaged. Once power is connected and the line set valves are opened per MRCOOL's directions, test the system in both cooling and heating modes.
Order your accessories with the unit so everything arrives at the same time.
FAQ 115V DIY 5th Gen MRCOOL Systems
What does "single zone" mean?
One outdoor condenser paired with one indoor air handler, conditioning a single defined space. It's ideal for a bedroom, office or garage where you want independent climate control.
Can homeowners truly install these themselves?
Yes. Mounting, line set routing and condensate drainage are designed for DIY, and MRCOOL says no special tools or training are needed. MRCOOL's manual calls for a licensed electrician for the electrical connections, and structural changes may need a professional.
How cold can these operate?
MRCOOL's standard 5th Gen models heat down to about −13°F. Higher-tier MRCOOL DIY models are rated lower, but those are 230V.
What line set lengths are available?
The 25-foot pre charged line set is included. MRCOOL also sells 11.5, 16, 35 and 50 ft sets in the same Quick Connect format, plus couplers for runs up to 75 ft. Check the maximum length and elevation in the manual for your unit. Zone Air cuts pre-charged sets to any whole foot from 5 to 75 ft.
What about warranty?
MRCOOL's DIY 5th Gen carries a 5-year parts and 7-year compressor warranty with no registration required. MRCOOL's paid Care Program is a separate monthly subscription. Zone Air's 115V units carry the same 5-year parts / 7-year compressor terms, and DIY installation does not void them.
Where should I buy?
MRCOOL sells through dealers and retailers. Zone Air sells its own units direct, and its shipping and return terms are among the best a customer gets in this category: 30-day returns on uninstalled units and free shipping to the lower 48. A reseller may not take a return at all and send you to the brand instead. Compare the specs above against your room size and electrical setup before you order.
Related guides
- 9,000–12,000 BTU 115V DIY mini split with pre-charged line set - the full install guide for a 9K or 12K system
- Best 115V DIY mini split: our ranked picks - Zone Air vs MRCOOL, Pioneer and Senville on 115V
- MRCOOL vs Zone Air - the two quick-connect systems side by side
- DIY mini split that plugs into an outlet - the 115V plug-in guide
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Specs and warranty terms are manufacturer-published as of November 2026, subject to change; verify before purchase. MRCOOL® and DIY 5th Gen are trademarks of their owner; Zone Air is a trademark of its owner. HVAC On Sale is not affiliated with or endorsed by MRCOOL.