Before you replace
your heating, ventilation, and air conditioning (HVAC) system, there are some
things you should know. The first is that a quality installation begins with a
Most of us don’t think about “design” when we think of
heating and cooling, but it’s just as important as a solid architectural
design. A professional HVAC contractor won’t simply replace what you have now
with new equipment. It’s possible that your existing system wasn’t sized
properly to begin with!
To make sure your new HVAC system meets your needs for
comfort and energy efficiency, a quality contractor performs a series of
calculations that take into account the overall climate where you live; how
your home is sited (for example, if it faces south or north); the amount and
quality of insulation in walls, basement or crawl space, and attic; how many
windows the home has and how efficient they are; other sources of ambient heat,
such as kitchen appliances and lights; even landscaping near the house.
These are called “load calculations.” The formulas, which
are included in ACCA’s Manual J®, were developed by HVAC experts at
ACCA and are the industry standard, often incorporated into local building
Turn to the pros
Why should you care about load calculations? It’s simple: an
under-sized system can reduce the comfort of your home, use more energy, and
not last as long as a properly sized system. An over-sized system will cost
more than you need to spend and may contribute to moisture-related problems
down the line.
Any contractor who tells you a load calculation isn’t
important is not a professional. The professional understands that your
year-round comfort is the ultimate goal. In the summer, your air conditioning
system not only cools your home’s air (sensible cooling), it removes moisture
(latent cooling). In the winter, your heating system must keep you comfortable
without causing high utility bills.
Insist that the contractor uses the Manual J residential load
calculation procedure. He or she will produce a computerized analysis that
indicates just how much heating and cooling capacity your new system should
provide. After the installation of your new system is completed, you will
receive a copy of the load calculation for your records.
The right equipment
The load calculation also enables the contractor to select
the right kind of system. Heating and air conditioning equipment comes in many
capacities, configurations, and efficiencies. It’s important that your
contractor selects the equipment that will be compatible with your home’s
heating and cooling needs.
Ducts, grilles, and
A qualified contractor will make sure the duct work in your
home is the right size and insulated properly. Properly installed and
maintained duct work can last twenty years or more, but time, heat, and
humidity can degrade the ducts’ insulation. In addition, ducts may have
collected contaminates over the years and need to be cleaned out.
Tell your contractor if some of the rooms in your home have been
too hot or too cold, as this could be a sign that the ducts are the wrong size
or are dirty. The contractor will evaluate the amount of air each room should
get and verify that your duct system is clean and configured to deliver the
right air to the right rooms.
Your return air grilles and supply air registers play an
important role in providing heating and air conditioning comfort, too. There
are times when simply replacing one or more of these devices can cause a
noticeable improvement in your home’s thermal comfort.
Return grilles that are undersized can reduce the efficiency
of the air conditioning system as well as the comfort in your home. Your
contractor will verify that these devices are sized and operating properly and
may make suggestions for improved performance.
Select a professional
Buying a new comfort system is a major expense, and most
homeowners replace their heating and air conditioning systems only every ten or
twenty years. It just makes sense – and cents! – to choose a contractor who
knows how to design, install, and service the right equipment for you. Using a
professional contractor assures you that your home will be comfortable for many
years to come.