If you’ve been shopping for a new central air system lately, you’ve
likely come across the term variable-speed compressor. Let’s break
down what that means exactly.
Single-Stage Air Conditioner
Many residential homes rely on central air conditioners that house single-stage
compressors. The reason for this is simple: single-stage or fixed-speed
technology was the standard in HVAC systems for many years and still operates
in many homes.
The way a single-stage air conditioner works is simple: When it kicks on,
it runs at full capacity until the temperature in the room reaches the
desired setpoint. Then it abruptly shuts down. It’s either on or
off. There is no in-between.
Imagine sprinting as fast as you can in short spurts. It’s more exhausting
than running at a slower speed for a longer distance. That’s because
sprinting requires more energy. That’s basically how your single-stage
AC unit operates. It’s inefficient and you’re utility bills
will reflect that.
Variable-Speed Air Conditioner
Air conditioners with variable-speed technology are more efficient because
they adjust their output based on fluctuating temperatures outside. For
example, if it’s 80 degrees outside and the thermostat is set to
76 degrees, your AC system will operate at less than half of its capacity
to regulate the temperature inside. That’s where the real energy
savings happen. Conversely, on hot days, the unit will ramp up capacity.
Variable-capacity systems will have a high SEER rating. That’s the
Seasonal Energy Efficiency Ratio. SEER is calculated by dividing the AC
system’s output over a cooling season by the energy it uses in Watt-Hours.
The most efficient systems will have a SEER of 21. The federal minimum is 13.
Variable-speed technology is also featured in most modern
furnaces. In this case, variable speed applies to the furnace’s indoor blower
motor. Because the fan moves at different speeds, it can more precisely
control flow to distribute warm air. For example, it can compensate for
factors such as a dirty or clogged air filter, increasing speed to push
out more air, ensuring consistent comfort. Additionally, the variable-speed
fan increases speed gradually, eliminating sudden and noisy starts to
a heating cycle.
But What About Two-Stage Heating?
In your search for a new central air system, you might find some furnaces
described “two-stage.” This has to do with the operation of
the burner inside the unit. On mild days, the burner will operate on partial
capacity. On colder days, it will open the throttle, so to speak, to deliver
more warmth. It’s another energy-saving feature and one worth considering
if you intend to slash your heating costs this winter.
More Benefits of the Variable Speed HVAC
Quieter: The lower, slower distribution of air means near whisper quiet operation
compared to the full-blast jet turbine of the fixed-speed system.
More comfortable: A variable-speed system runs for longer periods, delivering more consistent
temperature control and more even distribution of cool or warm air throughout the home.
More humidity control: Humidity can make a room feel warmer than it actually is. A longer run
cycle removes more humidity.
Cleaner air: Even without temperature control, you can keep the fan in constant operation
to circulate air, allowing the filter to capture more airborne particles.
Bottom line: When looking at a variable-speed furnace and air conditioner for your home,
you can expect the very best in both quality and performance. Both offer
superior comfort that helps your wallet and the environment. While they
are pricier initially, lower monthly energy bills will benefit you in
the long run. Tom’s Mechanical has more than half a century providing
quality HVAC installations throughout Arlington and surrounding communities.
To schedule an appointment, call (972) 954-2635.