18k BTU 20 SEER MrCool DIY Ductless Heat Pump Split System 3rd Generation - Wall Mounted

Item: HA20869
Models: DIY-18-HP-C-230B, DIY-18-HP-WMAH-230B
Condition: New
Looking for a mini split ductless HVAC system you can install yourself? The 3rd Generation MrCool DIY 18k BTU 20 SEER Ductless Heat Pump Mini Split System is the answer. You won't need any special training, tools, or equipment to set up this split system. It's a powerful mini split with a capacity of up to 18,000 BTU and can heat a space up to 750 square feet.

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This Bundle Includes

18k BTU MrCool DIY Ductless Wall Mounted Air Handler - 3rd Generation 18k BTU MrCool DIY Ductless Wall Mounted Air Handler - 3rd Generation Item: HA20865 Model: DIY-18-HP-WMAH-230B Qty: 1

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What customers are saying...



Looking for a mini split ductless HVAC system you can install yourself? The 3rd Generation MrCool DIY 18k BTU 20 SEER Ductless Heat Pump Mini Split System is the answer. You won't need any special training, tools, or equipment to set up this split system. It's a powerful mini split with a capacity of up to 18,000 BTU and can heat a space up to 750 square feet.

How simple is installation really? Crazy simple with the pre-charged Quick Connect line set, MrCool's cutting-edge technology that makes installation cost efficient, safe, and simple. And don't worry about space. The outdoor heat pump has many different installation location options. This option is a slim alternative at just 34 inches wide, 28 inches tall, and 15 inches deep, and it can be anchored to the ground or attached to a wall with a bracket. The indoor air handler is mounted to the wall and can seamlessly fit into your home to keep you comfortable year round.

The 3rd Generation MrCool DIY 18k BTU 20 SEER Ductless Heat Pump Mini Split System can operate in the winter in single digit temperatures, as low as 5°F, and its heating range indoors is from 32°F to 86°F. In the summer, keep your home cool to your liking with a cooling range of 63°F to 90°F. With this HVAC solution, you can stay comfortable year-round.

If you live on the coast and are concerned about salt water damaging your unit, the 3rd Generation MrCool DIY mini split comes with a Gold Fin Condenser that is built to withstand long-term exposure to salt in the air and resists corrosion. 3rd Generation MrCool DIY 18k BTU 20 SEER Ductless Heat Pump Mini Split System condensers are built to last with materials aimed at reducing repair calls.

The refrigerant in this 3rd Generation MrCool DIY mini split is R-410A, a more environmentally friendly option to the standard Freon. R410A is chlorine free and doesn't damage the ozone layer.

With MrCool, interruptions to your daily life are kept to a minimum. You can trust that your unit will run quietly and smoothly while it manages your home's temperature. The 3rd Generation MrCool DIY 18k BTU 20 SEER Ductless Heat Pump Mini Split System features an automatic horizontal louver. Set the louver so your home is evenly cooled or heated and the wall unit will automatically return it to that position once it begins its operation. Plus, in the event of a power outage, this mini split also automatically restarts as soon as power is restored, cooling or heating your home as quickly as possible.

The indoor air handler of this mini split system offers several modes so your HVAC can work according to your preferences. In AUTO mode, set a temperature and the unit will choose cooling, heating, or fan only based on the temperature in your room. In SLEEP mode, save money while you sleep as the MrCool reduces energy use through the night. You can also limit your energy use with the TIMER feature, which sets a timer for your heat or air conditioning.

The air handler features an Anti-Mildew Function that runs a low fan for 10 minutes after cutting off to dry out your unit. With this option, you can trust the air you breathe is clean and fresh.

The 3rd Generation MrCool DIY 18k BTU 20 SEER Ductless Heat Pump Mini Split System is smart and can be controlled wirelessly with the included remote, Google Assistant, Amazon Alexa, or from an app on your Apple or Android smartphone.

18k BTU 20 SEER MrCool DIY Ductless Heat Pump Condenser - 3rd Generation - DIY-18-HP-C-230B

MrCool HA20861

The only ductless air conditioning and heating unit that is easy to install for thousands less than a conventional HVAC system. Mr Cool DIY 18k Ductless Mini Split heat pump even adjusts the temperature to the perfect degree wherever you are in your room.

A MRCOOL DIY Series heat pump is the only ductless mini split system on the market explicitly designed for amateur installation. You don't need special tools or training to install this high efficiency heat pump. A line set precharged with R410A refrigerant, the quick hook-up electrical connections, and the quality engineering mean just about anyone can install a MRCOOL DIY in their home with no problem at all in only a few short hours. If you want great air comfort without paying an arm and a leg for installation, you want an easy-to-use MRCOOL DIY Series ductless heat pump.

Unlike any other ductless heat pump on the market, the MRCOOL DIY series is specifically designed for easy installation. The MRCOOL DIY series uses a precharged refrigerant line, alleviating one major obstacle to amateur installation in a single stroke.

MRCOOL ductless mini split air conditioners and heat pumps are the cutting edge of what modern, flexible fabrication can produce. These air conditioners rely on state-of-the-art manufacturing processes and advanced design to deliver high efficiency air comfort anywhere you need it.


  • EASY DIY INSTALLATION A pre-charged R410 quick connect DIY line set allows you to install this innovative ductless system without special tools, equipment, or training.
  • FOLLOW ME Personalized Performance for wherever you are in the room. Keep the remote close by, and MRCOOL DIY will track the air temperature around you to ensure you receive maximum comfort.
  • LOW AMBIENT COOLING Cool all the way down to 5°F. Maintain cooling even when the outside temperature reaches 5 degrees. This feature makes the MRCOOL DIY the ideal system for server rooms, greenhouses, and any other application that requires cooling all year.
  • AUTO RESTART Never lift a finger after a power outage. The MRCOOL DIY auto restart will have the unit running again in no time at all.
  • GOLD FIN CONDENSER Live on the coast? Don’t worry, our condenser is built to resist long term corrosion.
  • REMOTE APP WIFI CONTROL Control your DIY anywhere with your Apple or Android smart device and an internet connection.
  • TEMPERATURE COMPENSATION Our temperature compensation technology help keeps you comfortable in any weather conditions
  • LEAKAGE DETECTION When the MRCOOL DIY detects low coolant an alarm will sound to alert you to the problem. This will prevent damage to the compressor while you maintain high air comfort.
  • SLEEP MODE We made Sleep Mode easy to program to save money, and let you sleep a little easier.
  • LOUVER POSITION MEMORY The louver will automatically move to the same position as you set last time the unit was turned on.

Warranty Terms

For a full description of all warranties applicable to this product as well as individual manufacturer requirements, please review the manufacturer's consumer brochure and/or product warranty documents.  Online warranty registration must be completed within 60 days of installation.  Due to state laws, online registration is not required in California or Quebec. Call for warranty availability on scratch & dent and surplus items.

For additional warranty information, click here.


Model DIY-18-HP-230B25
UPC 810512033515
AHRI Number 204711123
Bundle Avg Coverage Area 750 - 900 Sq Ft
Bundle Cooling Capacity 1.5 Ton
Bundle Cooling Efficiency 19 SEER and Above
EER 12.5
Heat Pump Efficiency (HSPF) 10
Series DIY
Zones 1
Region Compatibility Nationwide
Popular Applications Game Room, Garage, Guest Room, Man Cave, Server Room, Sunroom
California Residents see Prop 65 WARNING

DIY-18-HP-C-230B Specifications:

Model DIY-18-HP-C-230B
UPC 810512033430
Avg Coverage Area 750 - 900 Sq Ft
Compressor Inverter
Cooling Capacity 1.5 Ton
Electrical Phase 1-Phase
Heat Pump Efficiency (HSPF) 10
Line Set Connection Type Quick Connect
Liquid Line Size 1/4 inch
Max Overcurrent Protection 20 amps
Primary Heating Capacity 15,001 - 20,000 BTU
Product Height (in) 27.64
Product Length (in) 14.29
Product Width (in) 33.27
Cooling Efficiency 19 SEER and Above
Series DIY
System Application Type Ductless Split Systems
Voltage 240
Warranty 5 Year Parts, 7 Year Compressor
Weight (lbs) 122.3600
Region Compatibility Nationwide

DIY-18-HP-WMAH-230B Specifications:

Model DIY-18-HP-WMAH-230B
UPC 810512033478
Air Flow Direction Horizontal
Configuration Wall Mounted
Blower Motor Variable Speed
Cooling Capacity 1.5 Ton
Electrical Phase 1-Phase
Line Set Connection Type Quick Connect
Liquid Line Size 1/4 inch
Max Overcurrent Protection 20 amps
Product Height (in) 13.19
Product Length (in) 8.9
Product Width (in) 42.52
Series DIY
Special Features WiFi Capable
Suction Line Size 1/2 inch
System Application Type Ductless Split Systems
Voltage 240
Warranty 5 Year Parts, 7 Year Compressor
Weight (lbs) 54.0100


Q & A

Do you have questions about this product?

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Can the MrCool DIY be ordered with a shorter line set?
What does it need for electrical connections
How close to the ceiling can this be mounted. The only spot I can put the unit is above a sliding door.
can I order a shorter lineset? 15 feet or ????
Are line sets (precharged) available in shorter or longer lengths?
Hi ,the electricity I have is 208/230 volt and McCool unit is 240 volt , Can I get any problems with the electricity if I do the connection? Or it will be okay
The installation manual states not to install in areas of prolonged sun. I need to install on the south side of my house( south central Kentucky), how would I be able to protect the outside unit? Thanks
A 15’ pre-charged line set is all I need , do you sell 15’ pre-charged line set with the mr cool diy kit
25’ is to much my job
does it come with the drain hose and the outside lines cover?
Can I order this with the shorter line set?
What is the minimum outside temperature that the unit will heat at 100% efficiency?
I’m doing a new construction man cave and haven’t run the wire for heating yet. What size wire do I need for the 18k unit? The room is 640 sf.
What size breaker does this require
I understand MrCool offers there DIY pre-charged units with 15' lines instead of 25' are you stocking them? looking at the 18K unit
I would like to substitute a 16' line set for the included 25' set. I presume this is possible? Thanks, Guy
is the unit complete with everything needed for a complete installation
What is the shipping cost to Florence MS 39073?
Since this bundle comes with a 25' lineset, can a 16' lineset be purchased separately and the 25' one included re-used for a different DIY set (combined with the required coupler?) Or does it come pre-connected in any way that would force it to be used with this bundle/kit.
I live in siuth-central Minnesota where winter temperatures cabnreach to well below zero. Will this unit operate in those conditions?
does this unit have a dehumidifier function?
Hi , I will like to know the measurements of the inside unit please
I have a room about 400 sq. foot, would the 12 seer work or would it be better to get the 18 seer?? it would be installed in a bonus room in north Georgia . it will be well insulated. thanks
how big should i make the footing for the outside unit?
is this precharged
Can you use two wall mounted internal units, with one outdoor condenser. I need to cool two separate rooms.
I see the heat pump condenser for the 12K is backordered. Is there any idea on when it will be available?
Does it require 220 electric ? I need dual zone 2 heads. Can u send me information on those?
What is the difference between 16 and 20 seer units?
I want to purchase but I see item is on backorder. Any idea about availability? Waiting lists?
Can I use a coupler with the supplied 25 ft line set and an additional 16 ft line set on the 18k 3rd Gen Ductless Heat Pump Condenser Model # DIY-18-HP-C-230B?
If I extend the line set does the system have to be charged?
Do you offer a dual zone DIY 18,000 BTU mini split system?
Where does the extra line go. I only have about an 8’ drop down the wall to the unit.
Is there a recommend condenser location for best operation? North side in the shade or south in full sun? That will determine my length of cooling lines
I'm going to be mounting this on an interior wall and while I have a path to an exterior wall/outside, I can't have enough of a slope to rely on gravity. What brand/model of condensate pump do you recommend for this unit (MrCool DIY 3rd Gen 18k BTU 20 SEER)? I'm ok spending more for a better pump that won't fail!
Is shipping included in the price of the 18K DIY unit?
I'm looking to get a 18K unit and would need a line set at least 40 feet long. Is there an option for that?
Although it's been previously asked, I would like to verify the indoor 18K unit dimensions as there appears to be conflicting information. The model line customer brochure states the 18K and 24K units are identical (42.52x8.90x13.19). While page 17 of the installation manual does have these dimensions for the 24K unit (in the schematic of the mounting plate). The dimensions for the 18K are listed as 38.0x?x12.55. My question is which is the correct dimensions? If the installation manual is correct, what is the depth of the unit? Thank you ahead of time.
18k BTU 20 SEER MrCool DIY Ductless Heat Pump Split System 3rd Generation - Wall Mounted

Question: Can you add a second Ductless Wall Mounted Air Handler to this unit in the future?
If so, what would be the item No. and cost?

Can you use the remote control and app interchangeably? For example, can I turn on unit with the remote and then turn off the unit with the app? Can I turn unit on with the app and change temperature with the remote?
How long is the line set that comes with this unit?
How many square feet will your 18K BTU 20SEER unit cool.
Could you tell me what the difference is between models HA20869 and HA18429 Thanks
Is this unit in YOUR stock? The reason I ask is, I ordered this unit from Lowe's, said it was in stock. Ordered on Jun 12th and it just arrived today, jul 7th. Come to find out it was a special from Mr Cool and they are in a three week back log.

I'm thinking of ordering another unit.

Thank you

I dont know how to formulate the question, but in case I need to buy just a piece or something in spefic like the control or the filter, can I just buy it with this company?
Do you have any units for more than one room?
18k BTU 20 SEER MrCool DIY Ductless Heat Pump Split System 3rd Generation: the distance from the inside wall location to the outside unit is only about 15 feet. What happens to the excess lines that run to the unit? Or would you suggest I buy the unit with shorter line lengths?
Thank you.
is shipping free like the other manufactures?
Can the line go up 3 ft into attic then back to ground level on Mr Cool DIY system?
can you getg this is 115v?
Will this product work if temperatures are below zero for extended periods of time?
Looking at the Mr Cool DIY 1.5 Ton system I noticed that it's listed with three parts - Heat pump condenser, wall mounted air handler and 25' line set. I notice that on the web site a 16' line set is available for the Mr Cool DIY. Can the 16' line set be substituted for the 25' line set and if so what would be the resultant system price?
How many square feet will the 18k unit handle ? Thanks
I am interested in purchasing a Mr Cool DIY 18000 BTU 20 seer 3rd Generation Heat Pump unit. Does the unit ship free?

HSPF? Utility Company wants to know?
Do the diy mr cool units come with the communication wire?
What do you do with the excess length of a line set?
could I see an installation guide 18k btu 20 seer diy mr. cool before I purchase? I would feel more comfotable knowing what I will be doing to get this installed.
In all of the videos that I have watched, the inside unit was high on the wall and the outside unit was on the ground. My installation will be the opposite. My outside unit will be on the roof, quite a bit higher than the inside unit. Is this going to make any difference?
What is the length of the lines attached to the inside air handler of the HA20869 unit?
Does this include the air conditioning?
I want to mount the air handler on the front wall of my house. Can i pipe the line set out the side of the unit instead of directly out the back?
Does it require 220v 3 prong or 4 prong plug and receptacle?
This unit comes pre-charged? So no HVAC Tech needed to pull a vacuum on lines and put a charge in?
I am wanting to install the MR Cool DIY 18K in my room-over-garage above a window on an outside 2x4 wall. Rather than drill though the outside wall for the inside unit, would I be able to come straight down so that I can then make a bend to go horizontal routing the line set through the internal wall then through a knee wall before exiting to the outside through the soffit down to the external unit.

Or, should I just abandon this idea and go straight though the outside wall and use the 4.5 in line set covers to keep from having to make the initial sharp bend and just keep all the line set outside?
Do you sell the cut off switch?
I am interested in ordering the Mr Cool DIY 18k Ductless Split System. The warranty states that it is only warranted if installed by a licensed HVAC contractor. If that is true, why is it sold and advertised as a DIY system? I will purchase and install the unit but not if the warranty is void by self installation.
do you guys take pay pal credit.?
Dear Sir, What is roughly your shipping time of two these units to California 95982 zip code. Are they in stock?
do you have lineset covers in stock? I just bought a MRCOOL 18K mini split and looking to buy the cover. Site mentions it is out of stock. Do i really need 4.5 inch? I have seen 4 inch covers on amazon. I don't want to force fit it in thought.


R/ Mike
Is 25' the longest lineset you offer with the 18k btu system? If not, what is the longest available single lineset without a coupler?
How quiet is this mini split?
Can this be ordered with a condensate pump?
Can you order longer Freon hoses?
Does the MrCool 18k unit have a dry mode or dehumidification mode?
I live in Louisville KY where winters can be as low as 20 deg one year and then next year it could get as low as below zero. This states good for 5 deg. Will this still work in my state if temperatures did get below 5 deg, what happens when temperatures are below the 5 degrees?
I would like to install a DIY 18k 2 zone system, the two air handlers will be a common distance of 25 ft from the heat pump then the two handlers will be 10 and 20 ft further. Do I need to run both handlers refrig lines all the way to the heat pump or can they be split at the 25 ft mark and continue to each handler. All lines will enter the home 3 ft from the heat pump, then run inside the home.
Do you sell the wall hanger support for the external Mr Cool unit (18000 BTU)
Hello, I am in the process of building a detached garage that I would like to heat and cool. It's built with 2x6 walls which are still studded out. Can I run the lines inside the wall? If so, is there any disadvantage of doing this? Also, do you offer a line set longer than 25'? If so, is there a disadvantage of running longer lines? And lastly is there a dehumidifier mode? Thank you!
The MR Cool web site lists the 3rd gen DIY mini splits as available with 16’ or 25’ linesets (precharged). Your web site says only 25’... Are you up to date with this information??
Do you still have the18,000 btu unit 230A and what is the difference in the unit and price?
any scratch and dent 18000 btu inverter units?
Does this come with the electrical wire?
I am looking at the 18K DIY unit, does the line come with the unit or do you have to add to the order from the accessories list, I assume you need to add? also what is needed to have what you need to install?
For power supply from the breakers, is 2wg (2 hot wires and 1 ground) adequate, or do you recommend 2 hots and 2 neutrals plus ground?
Can the power supply line be installed inside the protective cover, or would it interfere with the communication line?
I am installing the head on an inside wall. I think I read that ready access should be provided to the line set. I could do that with extra framing and a removable panel, but it would look a little weird inside the bedroom where it would be located. Your recommendation?
What are the measurements for attaching the 18K and 24K outside units to a concrete pad. Want to pour before I order. Would be nice to be able to preview installation instructions like some other brands I have looked at.
How noisy is it? Can I put the outside unit in the garage on the wall?
My whole house is 800 sqft how would this cool/heat my whole house when there are different rooms in my house?
I just asked a few questions but i thought of another one. How long is the line set that comes attached to the indoor unit?
Does your scratch and dent category mean that it is still new and totally functional? I am having an HVAC system installed in a small retail space ( a little less than 1,000 sq. ft.). But splint into two businesses. I am working with energy trust, and if this system qualifies, I am eligible for a rebate.
What's the difference between the diy version and the other? besides price?
18k but is it 120 volt or 220 volt?
For 18000 McCool unit do i need 10-2 or 10-3 wire to the condenser unit?
Can a condensate pump be used with this model?
Two questions: 1) if I wanted to cool/heat an additional room in the future, can I add that to this unit or do I need to purchase a different unit that allows that expansion? 2) My existing a/c is plugged into socket that has a dedicated line with 2-15amp breakers joined, with 240V rating. Will that work for this unit? Thank your.
Is this unit energy star rated?
I would like to purchase an 18k diy unit for my workshop, but I’m not sure about the line routing. I would need the lines to exit the left side, travel on the inside wall about 10 feet, and penetrate the adjacent wall to get to the outside. Going through the wall the head unit is mounted on is not possible. Can this be done?
I am looking at purchasing a 18k McCool ductless heat pump. I want to mount it over a set of windows but I only have 18”. I noticed in your specs that the wall mount unit is 13” and you recommend having 8-9” clearance to the ceiling which leaves me with only 5” of clearance. Is it possible my 5” clearance would be enough?
I need 50ft lineset and power lines. Can I get 50ft lines and pay the difference?
do you offer brackets for condenser unit to be attached to concrete foundation of house?
Is this Item in stock and how long does it take to be delivered :
Mr.cool diy 3rd generation 18000 btu spilt unit
Thank you for your assistance
Joe varro
does it come with the outside hose cover? is the 16 or 20 seer unit better?
Hello, I'm ready to buy a 18K Mini Split heat pump ITEM: HA20869. But I need a 30 foot long line set. At least that is my estimate of the existing line set length. I would even go for 35 feet line set to be safe. Is it possible to get a longer line set for this unit?
i live in the northeast. How do I know which units will heat to below 0 degrees
Is everything included for install?
I'm looking into getting the 18k btu unit for a poorly insulated room that im turning into a nursery. It gets hot in the summer and cold in the winter, my question is does this unit do both "heatin and cooling"?

When are you expecting for this item (ITEM: HA20869 MODELS: DIY-18-HP-C-230B, DIY-18-HP-WMAH-230B, DIY25-141) be available for order without being on back order? Same question for Model DIY-12-HP-C-115B?

I noticed you have these units as "scratch and dent items", are these truly cosmetic damage? The fin damage is concerning to me. Should I be concerned?
What's the longest line set if I get a 3 zone mini ssplit
Can unit be ordered with a shorter line set.
Do you have a ductless system that will work in below zero temperatures
Interested in 18K DIY Spit Ductless sys with 16' lines.
Is that available? OR...
Do I have to order the unit with 25' lines (throw them away) and order a separate 16' line set?
What is the difference between these two units? Other than the hose length. And seer rating?


my area I want to heat/cool is 9' tall x 14' wide x 50' long, what size of unit do I need ?
Can complete unit be mounted indoors?
Can the outside unit be mounted horizontally
We have the option to select 16' or 25' liner, but in some video Mr Cool 18K DIY only support 25' Liner, is the Mr Cool 16' liner option is also designed to work the same as 25' liner for pre-charged DIY?
Can i order your "18k BTU 20 SEER MrCool DIY Ductless Heat Pump Split System 3rd Generation - Wall Mounted" kit with a 50' line set instead of a 25' I saw you sell a union and 25' extension hose but the 25' extension is not in stock.

Can i install the "outdoor" unit in my mechanical room instead of outdoors? The room is approx 700 sq ft and has fresh air intakes from outdoors and is sealed from the rest of the house.
I purchased a Gobi II condensate pump from your website and have a question about installation with my MrCool DIY 18K. In order to connect the "Alarm" relay lines from the pump to the the MrCool air handler, I need to know the function of the "1" "2" "3" control lines on the Mr Cool unit. Are "1" and "2" power/common and "3" is the data line? I can't find this information anywhere online. Thanks!
I need a 35' line set , is that something i can buy ?? could i buy a 10 or 15' set and slpice them together ??
How long is the line that connects the outside unit to the inside air handler for this DIY Mini split ductless heat pump?
I live in Austin Texas and am looking to put a mini split in my garage to cool it down, since my wife uses it for a workshop.
Would the 18BTU McCool system be sufficient for this job? Dimensions: 25X22X8 and my house faces NE putting the garage at the NE corner.
Thanks for your help.

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