our opinions: ADVICE FROM AN EXPERT
In The
Comfort
Zone
Size matters when installing a new A/C
Brett Hobson
By BRETT HOBSON
CEO Comfort Experts
W
80
hen you’re digging a hole to add a new plant to your
garden, you want to use the best tool for the job. You
wouldn’t use a backhoe to add some petunias to your land-
scape. In the same vein, you wouldn’t want to put in a 10-ton
air-conditioning unit when a two-ton unit is what your home
really needs.
One of the things we hear most when someone calls need-
ing a new unit is that “my current unit is not cooling my house,
so I need a bigger unit.” That may or may not be the case. An
improperly designed duct system, leaking ducts, loose or poorly
sealed registers, or missing insulation can all make your system
work harder than it should. If you’ve called a reliable company
and had everything on your system checked and the result is
that you need a new unit, this is the time to make sure that the
unit that the company is recommending is the best one for your
home.
I know it’s a big investment. A new unit can cost thousands,
even tens-of-thousands, depending on the size of your home.
And often homeowners want a larger unit than the one that they
are replacing, because the current unit is not cooling or heating
the house to their desired level of comfort.
It’s time to ask some questions of the installation company
when they tell you what size unit they recommend. The first
one is how they determined what size unit you need. Don’t be
afraid, there is math involved. The contractor should have used
something called the “Manual J Load Calculation.” Luckily,
as the homeowner you don’t have to do the math, but you
should make sure that your contractor has. It is less work for the
contractor to guess at the size of the equipment than it is to do
a proper load calculation, according to Ron Therethy, author of
This Old House Heating and Cooling. An oversized system will
heat and cool, although it is not as efficient as a correctly sized
one and will not last as long as its potential. It’s cheaper for the
contractor to buy a bigger unit and cut corners on the installa-
tion.
There’s a myth out there that a unit that runs for a longer
period of time costs more than one that cycles. For example, a
four-ton unit will consume twice the energy that a two-ton unit
will if both run the same length of time. But when you factor
the cycling effect on efficiency the four-ton will consume up
to 20-percent more electricity. Electrical usage (expense) is in
direct proportion to system size and efficiency, so you want to
make sure that you are using the correct size system for your
home. In fact, researchers at Texas A&M have determined that
slightly undersized units are more efficient and better at provid-
ing comfort.
After the correct size has been determined, ask if new duct-
work will need to be installed. Make sure if they are using the
current duct system that it is clean and in good repair. You don’t
want to install a new system into leaky ductwork.
Ask about any new technology that is on the market. There
are great new tools like digital or remote-operated thermostats
that can greatly improve the efficiency of your system by learn-
ing when you are away from the house, or you can turn on
remotely. Anything that saves a few dollars is worth looking
into. Do some research and know what is out there.
Make sure the system you are installing is the most efficient
one possible. Ask about the unit’s SEER rating. The Seasonal
Energy Efficiency Ratio (SEER) measures air conditioning and
heat pump cooling efficiency, which is calculated by the cool-
ing output for a typical cooling season divided by the total
electric energy input during the same time frame. A higher SEER
rating means greater energy efficiency. Ask about the differ-
ent brands the company offers. Ask why they recommend one
brand over another. Ask about tax credits, rebates and what
guarantees the company offers on the unit they are installing.
Talk about service contracts and make sure you understand
what is covered in the guarantee. Also, make sure that all appli-
cable permits and approvals will be filed by the company with
the city before work begins. As always, make sure any company
that you are using is bonded, insured and licensed. And make
sure you understand the timeline for installation.
You have your estimate in hand, and you’re ready to get
started. But there is one thing I recommend at this point. Just
like when you get a difficult diagnosis from your doctor, I
suggest getting a second opinion. And even a third one if it
makes you more comfortable. Most companies are happy to
provide a second opinion and it’s just good business from the
customer’s standpoint to make sure you are getting the unit,
size, brand and system that your home needs.
And lastly, I know it’s uncomfortable, but you have to talk
about money. Because it’s not a budgeted amount for most
families, there may be payment plans to help out. Is there
financing available either from their company or from the
manufacturer? This is a big expense and a big investment. Make
sure your questions are answered and you feel as comfortable as
you can before work begins. It’s already a hot summer, but with
a new system, exactly the right size for your home, you can
look forward to years of cool comfort inside.