Customer Reviews

3 Ton 18 SEER MRCOOL Universal Series Heat Pump System



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AHRI Certified

AHRI Number:204117201

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The MRCOOL Universal Unitary Heat Pump system is an easy to install, full size air handler with a slim condenser, suitable for most 2-3 ton applications. This system is incredibly flexible, combining the ultimate in ducted comfort and easy installation. The 3 ton condenser can be field converted to a 2 ton with a different dip switch setting. The quick connect fittings on the condenser and air handler allow for an easy installation processes with MRCOOL's pre-charged lines, available as an accessory up to 50 feet in length. Using the same inverter technology used by the MRCOOL mini splits, the system can run at different speeds to optimize comfort and efficiency.


  • Comes with quick connect fittings for easy installations
  • 2 ton or 3 ton setting
  • 80% BTU output at -4°F oudside temperature
  • Fireproof electrical box
  • Upflow and horizontal installation only


  • No gas required; all electric system
  • Compatible with 3rd party thermostats; use your favorite or upgrade to a smart thermostat
  • No specialized tools required for installing the line sets
  • MRCOOL temperature compensation technology helps keep you comfortable in any weather condition

MDU18024036 System

  • MDUI18036 Indoor Unit
  • MDUO18036 Outdoor Unit

Product Specifications

More Information
3 Ton 18 SEER MRCOOL Universal Series Heat Pump System
SKU MDU18036
Weight (in lbs) 410.000000
AHRI Certificate Number 204117201
Brand/Manufacturer MRCOOL
Controller Not Included
HSPF 10.0
Cooling BTU 36,000 BTU
Heating BTU 36,000 BTU
Maximum CFM 1000
Decibel Level (dBA) Indoor Unit: 49 | Outdoor Unit: 60
Electric Heat Heat Pump
Electric Backup Heat Capabilities (Optional) 5 Kilowatts, 8 Kilowatts, 10 Kilowatts
Energy Star No
Refrigerant R410A
System SEER 18+
SEER (Efficiency) 18-20
EER 10.91
Condenser Stages Variable Speed
Compressor Type Rotary
Liquid Line 3/8"
Suction Line 3/4"
Electrical 230 V. 1 Phase 60 Hz
Max Breaker Size Indoor Unit: 15A | Outdoor Unit: 35A
Tonnage 3 Ton
System Tonnage 3 Ton
BTU/Tonnage 36,000 BTU/3 Ton
Mini-Split Type Multi-Positional
Min/Max Outdoor Temp for Heating -22°F-75°F
Min/Max Outdoor Temp for Cooling 5°F-129°F
Zone Compatibility Single Zone
Height Indoor Unit: 48.2" | Outdoor Unit: 32.3"
Width Indoor Unit: 21.3" | Outdoor Unit: 37"
Depth Indoor Unit: 21.3" | Outdoor Unit: 18.1"
Additional Info Indoor Unit: 217 lbs | Outdoor Unit: 156 lbs
Warranty 10 Years with Online Registration
Resources You will need Adobe® Acrobat® Reader to view PDF documents.
Safety Information PROPOSITION 65 WARNING

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Questions and Answers

Customer Questions
How to I determine what size of split system I need?
Hi, please give us a call and we can help you determine exactly what system and parts you'll need. We can also answer any other questions you may have during the searching and purchase process! Thanks
I was quoted that I need a 16 seer conventional ac what size would I need for a mini split
The tonnage you were quoted for the traditional AC would be the same tonnage you need for a mini-split system.
Can this unit be installed in the attic of a ranch style house?
Thank you for your question. The indoor air handler unit could be installed in your attic, however, it can only be installed in the up-flow position. Also when considering an attic installation, the quality of insulation plays a factor in the efficiency of your system. For more assistance, please give us a call at 1-888-377-2850.
Do you sell a top and bottom plenum? Can you give me a size for 3 Ton 18 SEER MRCOOL Universal Series Heat?
Thank you for your question. You will need bottom plenum that will match the dimensions of the furnace which are the following: 21-1/4" x 21-1/4" x 48-1/4". For the top you will need 11-5/8" x 20". We do have plenum options available. For assistance in finding exactly what you need, please give us a call at 1-888-376-5487.
Are there mounting sizes available for the condenser unit?
For mounting the condenser on the wall, we recommend this Diversitech mounting bracket for condensers. For more assistance, please give us a call at 1-888-377-2850.
My unit is gas furnace, so if I purchased this, it can be converted using only electricity?
Yes, you would use the air handler as heat, with the back up heat kit if needed. If you have any further questions, please call us and we will be happy to assist you.
Is 4 ton 18 seer Mr. Cool enough for 2000 sq.ft?
It very well may be but there are many other factors that can play into it such as location, insulation quality, etc... Please reference our sizing guide which can help you pinpoint the type of unit you need for your exact situation. Or you can always give us a call and we will be happy to further assist you. Thanks!
Downflow conversion?
Thank you for your question. This unit is specifically designed as an up flow system. However, you may want to check with the manufacturer or for assistance in finding a system that will work from a down flow installation, please give us a call at 1-888-376-7450.
Where are they manufactured?
MRCOOL is based out of Kentucky however most of their mini-splits are manufactured in China.
Do you carry a DIY mini split that would work for my shop? 30x45 with 14’ walls and 16’ total height at center.
Thank you for your question. Yes, we have several options that would be great for your needed application. However, the size of mini split that you will need is dependent upon your climate zone and the quality of your shop's insulation. Please reference our Sizing Guide to help you determine what kind of unit you'll be needing. If you have any further questions please feel free to give us a call.
Three rooms required. How many units needed?
Please reference our Sizing Guide that will allow you to know exactly what kind of unit you'll be needing as there are many determining factors such as insulation quality, location, etc... If you have any further questions please feel free to give us a call! Thanks.
I need a 3 ton heat pump with oil furnace back up 95kbtu?
We recommend that you give us a call so that we can get the right unit for you efficiently and answer any further questions you may have. Thanks!
Do you have a 2-ton 18 SEER unit ?
We currently have the 2-ton 20 SEER Heat Pump system by MRCOOL. If you have any further questions please feel free to give us a call! Thanks.
If the homeowner buys the equipment and puts it in their self can they get the 10 year warranty
The MRCOOL Universal products are not considered to be "DIY" like many of their mini split products. In order to receive the 10 year warranty for this product MRCOOL states that it must be installed by a professional installer. If you have any further questions please feel free to give us a call! Thanks.
Can I use my existing 3 ton evaporator coil and furnace?
You are able to do so as long as the tonnage stays the same and the same refrigerant is being used. However, you are not able to swap out a Goodman condenser with a MRCOOL condenser. MRCOOL cannot work with existing furnaces and coils; you would need to do a full system swap and get the MRCOOL air handler as well. Their air handler has an integrated coil inside as well as a blower motor, which requires a MRCOOL condenser to be matched with it. If you have any further questions, please call us and we will be happy to assist you.
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