Ductless Air Conditioners vs Central Air
Ductless Air Conditioners vs Central Air Conditioners which is better?
If you don’t yet know what a ductless air conditioner is, you will soon because they are the fastest growing segment of new AC units being sold and installed in the USA. Sometimes called mini-split air conditioners, ductless units are available in both cooling only and cooling and heating units.
Many ductless heat pump models can operate in extremely cold weather and provide heat in temperatures as low as -13°F, as well as providing cooling in extremely hot weather as high as 115°F. Many central air conditioning and heating systems a.k.a. ducted heat pumps do not operate well in these extreme temperatures.
In this article we’re going to focus on comparing the two types of air conditioner and heat pump technologies and the pros and cons of each so you can decide what’s the right choice for you and your home or commercial building.
Occupant Comfort: Uneven Room Temperatures – Hot Spots / Cold Spots
Recently my wife, sister-in-law, and I rented an AirBnB home in California while attending a family reunion. We were the hosts first guests since they did a complete remodel. Being an air conditioning and heating contractor for over 20-years, and an HVAC Technician for over 30, I just couldn’t help myself but to go look what brand and model AC units they installed.
They were American Standard 2-stage compressor units with variable speed indoor blower motors…pretty good stuff!
We used three bedrooms all next to each other (they were full-sized beds – the marriage is fine LOL) and they were all controlled by the same AC/Heat System. The nighttime temps were in the mid 50’s and the girls were cold so they turned the heat up to 72°. Both bedrooms they were staying in were at least 5°colder than mine, and I was cooking like a strip of bacon while they were still cold.
I had to open my windows in an effort to stay comfortable – not a very efficient option but clearly the duct design wasn’t great or the room to room temperatures would have been closer than they were.
As the name implies, mini split ductless systems do not utilize central air ducts, each room gets its own air handler. In this scenario each of us could have had the exact temperature we wanted had it been a ductless system. EX. I could have had my unit off, my wife could’ve had hers at 70°, and my sister-in-law (who’s always cold) could’ve had hers at 75°.
Not only would we have all been more comfortable, it would have saved the host more money on his utility bill….and I wouldn’t have had to leave my windows open while the heat was running!
Occupant Comfort
Central AC / Heating: Loser
Ductless AC / Heating: Winner
Which is More Efficient, Central Air or Ductless Air?
When it comes to air conditioner and heater efficiency ratings, get ready for acronym alphabet soup! There are several ways they are measured and these are some of the most common ones and what they mean:
SEER – Seasonal Energy Efficiency Ratio (or Rating)
Think of SEER like miles per gallon, the higher the number the better. SEER considers how efficient an AC unit is over the entire cooling season and the range of outdoor temperatures over the whole summer. The minimum efficiency allowed to be installed in Arizona, where my company, Magic Touch Mechanical is located is 14 SEER.
Central Air Conditioners typically range from 14 SEER to up to 23+ SEER. However, most brands and sizes top out in the 18-20 SEER range with only a few models and specific sizes that hit 23+.
Ductless Air Conditioners typically range from 16+ SEER to up to 30+ SEER. However, most brands and sizes start at 16 SEER and commonly are in the mid to upper 20’s.
EER – Energy Efficiency Ration (or Rating)
Think of EER like miles per gallon as well. The higher the number the better. EER considers how efficient an AC unit is at a fixed temperature (usually 95°).
This is another metric where ductless units typically rise above central systems. EER ratings are usually much higher in ductless units.
HSPF – Heating Season Performance Factor
HSPF is to the heating season what SEER is to the cooling season. This rating is used to measure the efficiency of heat pumps (gas furnaces use another metric known as AFUE).
As with the other two ratings we discussed, ductless heat pumps typically have higher HSPF ratings than their ducted counterparts.
Efficiency Ratings
Central AC / Heating: Loser
Ductless AC / Heating: Winner
Additional Ducted Central Air vs. Ductless AC Factors to Consider
Zoned Ductwork vs. Ductless AC Units – Zoning by Design
In the case of the AirBnB rental, there would have been more even temperatures room to room had the ductwork been designed better and had they installed an electronic zoning system with connected air dampers in the ductwork.
Electronic zone systems use multiple temperature sensors that work in conjunction with the dampers that open or close to deliver more or less conditioned air into individual areas of the home. While zone systems serve a roll and help increase comfort, they do not save energy – in fact they can be wasteful. Typically, zone systems control a group of rooms or an “area”, not each room individually.
Think about it this way; if the system’s total capacity is 3-tons, it’s always using all the energy it takes to run a 3-ton machine just to cool or heat one or two rooms. The rest of the unneeded “energy” that was already used (and you paid for) is wasted.
However, ductless air conditioners offer extremely precise zoning (per room) with zero waste. In the case of the rental, if the systems total capacity was 3-tons, and the two running air handlers (one in each room) were say ¾ of a ton each, the ductless unit would only use the energy needed to run 1.5 tons…a 50% decrease in energy consumed.
Zoning
Central AC / Heating: Loser
Ductless AC / Heating: Winner
How “Duct Loss” Impacts the Size of an Air Conditioner
If you’re researching air conditioners, you probably already know bigger is not betterwhen it comes to HVAC (Heating, Ventilation, and Air Conditioning). Installing a 5-ton air conditioner where a 3-ton air conditioner is needed thinking it will blow harder or colder air will produce the opposite results. Oversized air conditioners actually cause more problems and make people less comfortable than undersized air conditioners.
Don’t buy an undersized or oversized air conditioner, buy the right size air conditioner.
The onlyway to assure the “right” size air conditioner is by completing an ACCA Manual-J load calculationaka Heat Gain / Loss Analysis.
TIP: If you have the time and means, having a home energy audit conducted before the load calculation is completed is even better. That’s because adding the exact duct leakage, home leakage (building tightness), Insulation R-Values, etc. help make sure the results are as precise as possible, as opposed to using the “assumed” software defaults.
Here in the Phoenix, AZ area where most ductwork is located in the hot attic and walls, energy loss as the air passes through these ducts is tremendous and rapid. This is because the energy loss is multiplied by multiple factors.
By eliminating the duct work you eliminate the energy loss.
It is not unusual to run two side by side load calculations for the same home, one modeling a whole home ductless heat pump system and the other a conventional ducted central air and heating system and needing only 50-60% of the capacity with the ducted system.
In other words, needing a 5-ton system with the ducted unit but only needing a 2.5-ton to 3-ton unit with the ductless system. Equal performance and results, but a 40-50% energy reduction just by eliminating the duct loss…beforewe even consider the zoning factor!
Duct Loss
Central AC / Heating: Loser
Ductless AC / Heating: Winner
Cost to Install a New Ductless System vs a Ducted Central Heating and Cooling System
When comparing installation costs, I’m going to focus on replacing an existing air conditioning and heating system in a completed home. Our specialty at Magic Touch Mechanical is retrofit replacement in existing homes so we see the cost differences in many applications.
TIP: If having a new home built, it is worth asking your builder if whole-home ductless or a hybrid of ductless/ducted options are available. The cost difference between the two should be much narrower if planned before construction.
The reason it’s important to specify retrofitting existing homes is the ductwork, electrical wiring, refrigerant plumbing lines, low voltage wires, concrete slab, and many other things are already in place. Assuming all of those items are properly installed, are in good condition, and don’t need to be replaced, significantly lowers the cost of replacing a ducted system with another ducted system.
In the case of the ductless system (assuming it’s not replacing another ductless system) all of those ancillary items need to be installed for the first time, significantly raising the price of a ductless system over a ducted system. We often see the final costs to install a whole-home ductless system being between 2-4 times higher than central air.
If we were talking about replacing just the ductless equipment where a previous ductless system was already installed, it would be a much more equal match.
Installation/Replacement Cost
Central AC / Heating: Winner
Ductless AC / Heating: Loser
Comparing the Durability, Reliability, and Longevity of Ducted vs Ductless Heat Pumps
As the owner of an air conditioning and heating company, I have a love/hate relationship with ductless units.
I love them because they are more durable, reliable, and last a lot longerthan today’s conventional ducted central cooling and heating systems.
I hate them because they are more durable, reliable, and last a lot longer than today’s conventional ducted central cooling and heating systems.
I have many service technicians that rely on me to have enough repair calls to keep them earning a year-round, full-time living. The ductless units we mainly install (Mitsubishi Ductless AC) are tanks and have a very low failure rate as compared to traditional equipment. Less breakdowns equal less repair calls.
While that makes for a happy client and installers (both of which I rely on to earn a living myself), it makes for a less happy service technician whose main roll is fixing broken air conditioners!
The good news for our service technicians is although they break down less often, they require a highly-trained professional when they do…so, I guess I can change it from love/hate to just love!
Durability, Reliability, Longevity
Central AC / Heating: Loser
Ductless AC / Heating: Winner
Return on Investment and User Satisfaction
Comparing the ROI of ducted vs. ductless really boils down to the individual application, user settings, lifestyle, and the upfront costs of installation. All things being equal, the ductless system ROI would far outpace the ducted system ROI – but in a real-world scenario all things are rarely equal.
Yes, in most applications the ductless system is going to cost significantly less to operate, require less money spent on repairs over the years, and will last longer before requiring replacement again, but – some whole home ductless systems can cost 2-4 times a ducted system upfront.
My advice is to think more about comfort, low-noise, and reliability than energy savings and ROI when considering which type of system is right for you. Think about the additional efficiency savings as the icing on the cake, because…
Customers LOVE their ductless systems, the same can’t be said about customer satisfaction of ducted systems. Magic Touch Mechanical has tens of thousands of clients as we’ve been in business for over 20 years. For the life of me, I can’t think of one ductless client we have that doesn’t rave about how happy they are with it. I wish I could, but I can’t say the same about ducted systems.
ROI and User Satisfaction
Central AC / Heating: Loser
Ductless AC / Heating: Winner
Am I Biased?
HVAC Contracting pays my bills. My company has installed thousands upon thousands of ducted central air and heating systems over the last two decades. I suspect we will install thousands upon thousands more over the next two decades.
At the pace the interest in ductless equipment is growing, we have no reason to believe we will install more and more of them over the coming years as well.
I’m biased in favor of Magic Touch Mechanical! I just want people in the Phoenix area to choose us over our competitors – whether it be to install or service a ducted or ductless system.
That said, my opinion if money were no object – ductless over ducted hands down. Rarely is money no object however, so compare your application and then decide what’s most important to you!