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MRCOOL® DIY 5th Gen · Multi-zone · 3 rooms
3-Room DIY Mini Split System, 55,000 BTU Outdoor Unit
Price includes your line sets below
1. Pick a line set length for each room
How do I measure?
Measure along the wall from where the indoor unit will go to where the outdoor unit will sit, then add 3 ft. Pick the next length up. Extra line set coils behind the outdoor unit. It can’t be cut.
Want to mix wall units and ceiling cassettes? Build your own →
66 ft and 75 ft are two line sets joined with a coupler kit. The kit is included in that price.
2. Add what you’ll need to install it
Not in the box. Most installs add a line set cover, a disconnect, a whip and a pad.
Ships from Kentucky 2 to 4 business days after your order is verified,
then 3 to 7 business days by freight.
Sizing questions? Call +1 (844) 999-9725 Mon–Fri, 9–5 EST
You can install it yourselfPre-charged lines, no vacuum pump
Each room its own temperatureSet each room from the app
Heats down to −13°FCools in summer, heats in winter
5 yr parts, 7 yr compressorCovers a DIY install
Will it fit your home?
Each indoor unit is sized for one room. Check your rooms against these, length times width.
A room is bigger than its unit? Pick a system with a bigger unit for that room, or call us and we’ll find the right mix. Sizing guide
What’s in the box, and what isn’t
- 55K outdoor unit, factory charged with R-454B
- 3 wall units (18K, 18K, 18K), each with its mounting hardware and remote
- 3 pre-charged Quick Connect® line sets, the lengths you pick, sized to each unit
- Communication wire and drain hose for each room
- Install and owner’s manuals
Not in the box
Every multi-zone outdoor unit runs on 230V and needs these. Tick them in step 2 above.
- Disconnect switch, 60A, and an electrical whip
- Outdoor pad
- The 230V circuit and breaker from your panel
Can you install a 3-room system yourself?
Yes. It’s the same job as a single room, done 3 times, plus one outdoor unit. Plan a weekend or two.
“Easy install. Took me 2 full days to install 4 wall units.”Michael, Trustpilot
- Hang each indoor unitWall plate into studs, one hole through the wall per room.
- Run each line set to the outdoor unitEach room connects to its own port on the outdoor unit.
- Connect, power and testSnug the Quick Connect fittings, one 230V circuit with a disconnect, then check for leaks.
The part people ask us about
The electrical. The outdoor unit needs one dedicated 230V circuit and a disconnect within sight of it. The indoor units are powered through their communication wires, so no outlets are needed inside.
If you’ve never added a 230V circuit, have an electrician do just that part.
Line set limits from MRCOOL
From the 5th Gen multi-zone install manual. The picker above keeps you inside these.
Shipping and returns, in plain words
When it arrives
Business days, counted once your order is confirmed. Free shipping on kept orders in the 48 contiguous states. Hawaii and Alaska ship by quote.
How it’s delivered
Freight truck with a liftgate, set down at the curb. It may come in several boxes, so have someone help carry them in.
Box damaged? Refuse only the damaged item and keep the rest. We ship a replacement right away.
If you change your mind
Cancel before it ships and you get everything back except the 3% card processing fee. After it ships, email us first. The 3% fee, shipping both ways and MRCOOL’s 10% restocking fee come out of the refund. Return policy
MR COOL DIY IS THE BEST.
“I’ve had for about a year now and the performance has been flawless. It was a diy installation and I didn’t have any problems.”
Mr. BakerBest price and fast shipping
“Good experience, best price and fast shipping. Had a question and they got back to me quickly. I bought the Mr. Cool 36000 btu 3 zone mini split.”
Barry BowenGreat people
“Easy to talk with, made sure I was getting the right system for my needs, great price, and followed through with communications till delivered.”
Pete SwegerAs easy as they claim
“It was actually as easy to install as they claim it is… couldn’t be happier with the performance so far.”
JimPiece of ‘Cake’
“The rep on the phone was helpful with confirming that… I’m amazed at how straightforward the process is. Should be fun, and I’ll save a lot of money.”
Byron GabrielsenDIY 2 zones, 18k
“Packaging and shipping was great. Response time to questions was good. The two zones are performing nicely, and super quiet!”
K. WestfallDelivery handled
“Your help coordinating and managing the delivery was excellent. You have a great team.”
Andy ArenthVery helpful sales
“Cool-minisplits website beat everyone on price… I called and found out that they are very reliable… Items shipped out quickly and arrived in good condition.”
Robert JohnsonGreat customer support
“The order came quickly. One part was damaged by the carrier so I called and they immediately shipped a new part.”
Zac HGreat and honest business
“The 24k Mr Cool was a perfect solution for my garage… Easy install and the staff are always there to answer any questions.”
Todd BaileyEasy install
“Easy install. Took me 2 full days to install 4 wall units.”
MichaelMr. Cool as a DIY project
“I was very interested in the DIY portion of the product. It was involved, but I’m fairly handy and found it very doable and everything works fine.”
WaltGreat service
“Purchase went without a problem and all my questions were answered without delay. I was notified when the unit shipped.”
Scott IverslieAttention to detail
“I threw him so many curveballs and order changes and he still got it all correct… Appreciate all the personal attention to detail and following up.”
Tim HedrickTop notch
“Their customer service is too notch! The product is amazing!!!! … I recommend this to any Contractor any homeowner anyone who’s looking for a mini split system!”
Dean R Sun
Multi-zone questions
Can the rooms add up to more than the outdoor unit?
Yes. This system is 18K + 18K + 18K = 54K on a 55K outdoor unit. That leaves room to spare, so every room can run at full power at once.
Can I pick a different length for each room?
Yes. Each room gets its own line set, sized to its unit. Pick the shortest length that reaches.
My run is longer than 50 ft. What then?
Pick 66 or 75 ft. You get two line sets and a coupler kit to join them. 75 ft is the most MRCOOL allows for one room.
Can I add a room later?
This system uses 3 ports on the outdoor unit. If you might add a room, call us before you order and we’ll check which outdoor unit leaves a port free.
Do I need an HVAC technician?
Not for the refrigerant side: the line sets are pre-charged and connect with two wrenches. You may want an electrician for the 230V circuit.
Do you help with the install?
We don’t do installs or install support. Call before you buy and we’ll help you pick the right system. After that, the manuals and MRCOOL support are the place to go.
Full product description
The MrCool DIY 3 Zone Mini Split featuring a 18K-18K-18K configuration is a versatile system ideal for a master suite and 2 standard rooms. Featuring the maximum capacity 55k condenser, this industrial grade residential unit ensures peak performance even in extreme temperatures for large properties.
Optimized for single story homes or targeted floor coverage, this three zone system ensures you stop wasting energy on empty rooms. It grants independent control to your most used spaces, keeping living areas cool and bedrooms comfortable without the waste of a central unit.
Every home layout is different, which is why this system moves beyond standard piping. Select the exact pre charged Quick Connect line set length you need for each indoor unit directly from the menu above. Available in 16ft, 25ft, 35ft, 50ft, 66ft, and 75ft options, our custom selection ensures you do not pay for excess copper or struggle with lines that are too short.
What is Included:
- 1x 55k Outdoor Condenser
- 3x Indoor Air Handlers
- 3x Remote Controls and WiFi Dongles
- 3x Selected Line Sets (Your Custom Lengths)
- 3x Communication Wire & Drain Hose
Delivery Note: This item ships via LTL Freight. The carrier will call to schedule a curbside delivery appointment.
Ready to order?
3-room DIY 5th Gen system, 55K outdoor unit, free shipping to the 48 states.