Is a variable capacity air conditioner worth the higher cost?
Yes, but only in very hot climates, especially where it is both hot and very humid.
That’s the short answer. For most homeowners, a variable speed AC is not worth the high cost unless you live in one of those really hot and humid regions of the country.
Most of us won’t get a great return in terms of:
1). Savings on your energy bill vs higher upfront cost – it will take at least 8 years to recover the higher cost through lower bills, and in moderate to cool climates, you will never be paid back.
2). Climate control – Yes, variable speed air conditioners offer better control of precise temperature balance and dehumidification, but not enough to make a noticeable difference in most homes.
If you want the details, they are discussed below.
What is a Variable Speed Air Conditioner?
And what is it not?
What It Is
A variable speed AC is also called a variable capacity and a modulating AC. It has a compressor that adjusts in small increments rather than having one speed like a single stage AC or two speeds like a two stage AC.
The compressor of any AC or heat pump – they make variable speed heat pumps too – pumps the refrigerant through the system, circulating it into your home where it picks up heat during an AC cycle.
The hot refrigerant cycles outside into the condensing unit where the compressor compresses it – hence the name – and “squeezes” the heat out of it, which is released through the radiator-like outdoor coil.
What It Is Not
The term does not refer to the variable speed blower motor in the air handler, though all variable capacity ACs are paired with a furnace or air handler with a variable speed blower.
How Many Speeds Does a Variable Speed Air Conditioner Have?
60 to 750!
What? Yes, that’s right. Variable capacity compressors modulate from 25% to 100% like the Trane XV20i and 40% to 100% like most other variable speed AC models including the new Lennox SL28XCV.
Trane says that it’s variable speed compressor adjusts to the demand for cooling in .1% increments – 75 divided by .1 = 750 speeds.
Lennox and most others adjust in about 1% increments, so from 40% to 100% is 60 stages.
Variable Speed Air Conditioner Pros and Cons
The advantages and disadvantages of variable capacity air conditioners are clear.
Higher efficiency – All major manufacturers make variable speed ACs, and those units are the most efficient from that brand. The most efficient models from Trane and Lennox are mentioned above.
The other top variable speed air conditioners are listed below along with their specs for comparison.
The most efficient variable capacity ACs are usually 2 SEER to 8 SEER more efficient than the most efficient two stage models the brands sell.
Balanced temperature – A single stage AC keeps the temperature in your home within 2-3 degrees of the thermostat setting. Two stage units keep it within 1-2 degrees of what the thermostat wants. Variable speed AC units hold the temperature within a half-degree or closer.
Better humidity control – The key to dehumidification is circulating the air in your home over the cold indoor coil. Moisture condenses on it and drains away, reducing the humidity in your home. A system running at 40% or 50% has longer cycles than one running at 70% (2 stage unit on low) or 100% (2 stage on high or single stage running any time).
Longer, slower cycles allow for more effective moisture removal – dehumidification of the muggy air.
Better air filtration – Those longer, slower cycles also allow the air filter in the system to more effectively remove pollutants, allergens and other debris from the air in your home, resulting in better indoor air quality (IAQ).
Better resale value – When homebuyers look at an HVAC system, they often consider the efficiency above all else. “Wow, 28 SEER and really low energy bills?” They love it, and the super-efficient AC might help you sell your home.
Higher equipment cost – According to one large Arizona HVAC contractor, the cost of variable speed equipment is “$4,000 to $8,000 more than other units.” That might be a little high, but it depends on which units you’re comparing a variable speed air conditioner to.
Generally, we agree. You’ll pay at least a couple thousand dollars more for the benefits listed above. It’s not just the AC unit – which is the bulk of the cost. You also need an advanced communicating thermostat like the Trane ComfortLink II thermostat at about $600 or the Carrier Infinity System control at $500+.
Higher repair cost – If a modulating compressor fails, you’re looking at a $2,000 – $3,000 repair bill versus maybe $800 to $1,500 for a single stage or 2 stage compressor.
Potentially bad installation and resulting problems – Your HVAC company won’t send the rookie out to install a variable capacity air conditioner. It takes a well-trained, experienced technician.
And if the installation isn’t done correctly, the “communicating” technology might fail to connect, and the system either won’t work or won’t work properly.
It takes doing it right for you to get the efficiency and climate control you expect from variable capacity equipment.
2 Stage vs Variable Speed Air Conditioner
A two stage AC has a low setting, which is 65% or 70% of capacity, and it runs on low whenever that capacity is sufficient to keep the thermostat satisfied. It runs on high – 100% – on really hot days or when you turn down the thermostat by more than a few degrees.
So, a two stage AC does a better job than a single stage AC of removing humidity and filtering the air.
But two stage air conditioners are not as efficient as most variable speed ACs:
Two stage efficiency range: 16-20 SEER
Variable speed efficiency range: 18-28 SEER
And they don’t have quite the same amount of airflow, so filtration isn’t as complete.
Because variable capacity ACs are more prone to installation errors, 2 stage units are considered more reliable. But again, most of the issues stem from installation. If you choose a variable speed AC, get written estimates from several local contractors, and choose one with experience and good reviews.
We’ll cover the cost difference next.
How Much Does a Variable Speed AC Unit Cost?
Expect to pay $8,500 to $11,500 for a 3 ton variable speed air conditioner. But the total cost range is wider, as shown below where we compare the cost of a two stage AC to a variable speed AC.
How much more expensive is variable speed air conditioner?
Here are cost averages for both types of air conditioner. These are installed costs.
Two stage: $4,600 – $9,000
Variable capacity: $6,800 – $13,000
Is a Variable Speed Air Conditioner Worth It
For $2,400 to $4,000 for most brands you can upgrade from a two stage to a variable speed AC. The jump in cost between a single stage AC and variable capacity air conditioner can be closer to $5,000 to $8,500.
Is it worth it?
It might be if:
Your climate is very hot – like Arizona hot – or super-hot and humid like many parts of the Southeast – think Atlanta – or South – all of Louisiana.
You value the greenest air conditioning available – the most environmentally friendly.
You place top priority on a very comfortable indoor climate.
Do the math – How much do you pay per month in electric costs? What might your cost savings be in terms of electrical costs by upgrading your AC’s efficiency by 20% to 50%?
Next, we break it down by state – Is a variable speed AC worth it where you live? Let’s find out.
|States||Worth it or Not (Yes, No, Possible)|
|Colorado||Yes - In southwest CO|
|California||Possibly in SoCal. Probably not in central and NoCal.|
|Illinois||Possibly in southern Illinois where it is hot and humid|
|Indiana||Possibly in southern IN|
|Kentucky||Yes, in non-mountainous parts of the state|
|Nevada||Yes, in the hotter parts of NV|
|Ohio||Possibly in southern OH|
|Kansas||Possibly during the hottest stretches|
|New Mexico||Yes in the hotter parts of NM|
|North Carolina||Yes - but probably not on the coast our in the mountains|
|Tennessee||Possibly in the warmest parts of TN|
Top Variable Speed Air Conditioner Units
Here are the best brands and their specs including the cost of a variable speed AC from each.
|Trane||XV20i||2-5 ton||21 seer||$9,400 - $12,000|
|Lennox||SL28XCV||2-5 ton||28 seer||$9,600 - $13,200|
|Carrier||24VNA6||2-5 ton||26 seer||$9,750 - $12,800|
|Goodman||GVXC20||2-5 ton||24.5 seer||$8,900 - $11,000|
|Rheem||RA20||2-5 ton||20.5 seer||$8,350 - $11,200|
|American Standard||Platinum 20||2-5 ton||22 seer||$9,550 - $12,250|
Note: The Goodman GVXC20 was recently upgraded from a 20 SEER unit to a 24.5 SEER model. You’ll find both versions for sale online at quite different costs, so be sure to know which one you are buying.
Does variable speed air conditioner make it quieter inside than a standard air conditioner?
Yes, definitely. Variable capacity ACs use an inverter-style compressor that runs in the mid-50s decibels. Standard single stage or two stage ACs have noise levels ranging from 65 to 78 decibels.
What type of furnace (single stage, two stage and variable speed) is needed for a variable speed air conditioner?
The key is the blower – you need a variable speed blower fan to get the best efficiency and indoor climate control from a variable speed air conditioner.
Variable speed blower motors are found in all variable capacity furnaces and many two stage furnaces.
What is communicating technology? Do I need a communicating thermostat?
It means that the thermostat, instead of just sending information to the AC about how fast to run, also takes data feedback from the AC. This allows it to make the necessary, precise adjustments to optimize temperature balance and dehumidification of humid air.
Yes – communicating thermostats are their own type. Each major manufacturer makes communicating thermostats to use with some two stage and all variable capacity air conditioners.