Key Takeaways
- First Mini-Split: The Comfort-Aire Twin Pac, developed by Heat Controller in 1969, was North America’s first true mini-split air conditioner
- Evolution of Efficiency: Mini-splits evolved from sub-8 EER ratings in the 1980s to modern units achieving 30+ SEER and 15+ EER ratings
- Lineset Capabilities: Maximum refrigerant line lengths increased from 19 feet in early models to over 160 feet in modern systems
- Market Impact: The original Twin Pac won Michigan’s Product of the Year in 1974, beating the Ford Mustang in the automotive capital
The Past: Birth of the Mini-Split Revolution
Prior to my time at Bathica TOSOT, I did some contract work for Heat Controller, Inc. out of Jackson, MI. You know them by the brand name Comfort-Aire.
I had the pleasure of learning the history of the mini split from a man who lived it, Mr. Don Peck, the CEO of Heat Controller at that time and an employee there for over 50 years.
Why Were Split Systems Developed?
Don was always proud to tell me that the FIRST mini split was developed by Heat Controller. Here are his exact words:
“The first introduction in 1965 was the Comfort-Aire Twin which was a window air conditioner with a split cabinet design that allowed the window to close into the center of the unit with the compressor and the condenser fan on the outside of the window and the indoor fan on the inside making for a very quiet application.”
The Revolutionary Twin Pac System
The Twin Pac, the first true mini split, was an offshoot of the Twin and was originally developed for Sears in 1969. It went by the name “Sears Modular Central Air Conditioning System” and offered two sizes: a 6000 BTU (115V) and 16000 BTU (230V) model.
The original units featured only 8 feet of refrigerant lines with quick-connect fittings and included a double wrench kit for making the connection. This was revolutionary for the time, as it allowed for easier installation compared to traditional window units or central systems.
In 1971, the Twin Pac became available under the Comfort-Aire label. Three sizes were then offered (6000 BTU, 11000 BTU, and 16000 BTU), and the line set accessories were upgraded to allow for up to 19 feet between the indoor and outdoor units. WW Grainger and Harry Alter Co. were probably the largest wholesale customers.
The product eventually left the market when the federal government instituted the first EER rating requirement of 8.0 in the late 1980s, as the product was classified as a split system rather than a room unit. Understanding how refrigerant works in these early systems helps explain why efficiency improvements were so challenging.
A Piece of History
Here is an actual piece of literature for the Comfort-Aire Twin Pac:
Look at the indoor unit – seems like EVERYTHING was wood grain back in the 70’s!
Don always made a point to say that in 1974, the Comfort-Aire Twin Pac won the Product of the Year award in the state of Michigan. It beat out the 1974 Ford Mustang, which was quite an achievement.
Now, you might say that just about anything should have beaten this particular car model…
But those of us who are old enough to remember know that Ford sold a bunch of these cars, and for any non-automotive product to win in Michigan was unheard of at the time!
The Present: Modern Mini-Split Technology
Now, let’s climb into the 1982 DeLorean DMC-12 and set the flux capacitor to 2021. That’s fifty-two years forward from the introduction of the first mini-split in North America.
In those fifty-two years, we went from the lunar module to the space shuttle to SpaceX. We went from the 1969 Ford Mustang with a 390 cubic inch, 6.4-liter V8 motor to the 1974 Mustang II with a 2.3-liter 4-cylinder motor to the 2021 Mustang Shelby GT500 with a supercharged 5.2-liter V8 producing 760 HP.
And we went from the Comfort-Aire Twin Pac in 1969 with an EER of something less than 8 to the TOSOT LOMOPLUS…
Comparing Yesterday and Today
A 12K LOMOPLUS indoor unit measures just 39.9″ long × 12.1″ high × 8.7″ deep. No funky wood grain, but rather a simple, discrete, clean appearance that blends with modern interiors.
The Comfort-Aire Twin Pac of the early 1980s left the market because it couldn’t meet an EER of 8 required back in the day. The LOMOPLUS? The 12K LOMOPLUS achieves an EER of 15.3 and a SEER of 30.5 (the 9K LOMOPLUS has an EER of 16.5 and a SEER of 38).
The Comfort-Aire Twin Pac had a maximum lineset length of 19 feet. The TOSOT LOMOPLUS TW24HQ3D6D has a maximum lineset length of 164 feet – now that’s progress!
These efficiency improvements are crucial when calculating proper heat loads for modern installations, as oversizing based on old efficiency standards can lead to comfort and humidity issues.
Just as mini-split technology has evolved dramatically over five decades, so have the tools available to HVAC professionals. Property.com’s ‘Know Before You Go‘ tool helps contractors leverage modern technology by providing detailed homeowner insights, including permit history and potential efficiency upgrade opportunities – perfect for recommending high-efficiency mini-split systems to customers still using outdated equipment. Join the exclusive network of certified contractors who are using data-driven insights to grow their business.
Learn More with HVAC Know It All
The evolution from the Comfort-Aire Twin Pac to today’s ultra-efficient mini-splits represents one of the most dramatic improvements in HVAC technology. Understanding this history helps technicians appreciate the engineering advances that make modern heat pump systems so effective.
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