Central Air Conditioning
What consumers should know before they install a central cooling systems.
With summer heat underway here are some heating and air conditioning tips to help you stay comfortable. Many central air conditioners units will be
repaired or replaced. Additionally, the rise of summer heat also means a rise in electric bills. One of the most expensive appliances you’ll purchase
for a home is a central cooling system (only to be rivaled by the heating system). Finding the right central cooling system for your home is largely
dependent on the contractor you choose.
The beauty of a central air conditioning system is that it can distribute cool air through the whole house as opposed to window units which are
generally designed to cool a single room. Despite the larger initial cost, a central cooling system can still save you money by reducing your monthly
utility bill. If new or modified duct work is required, then your initial investment will rise. Central air conditioning units also vary in size and efficiency.
A common, costly error is to install an over sized unit in your home.
Choosing the right unit for your home will largely depend on the contractor you choose because he will determine the capacity required. A good
contractor will estimate the cooling loads and duct requirements by collecting detailed information in your home and using industry calculations to
determine the correct size. (For more information on how to select a contractor, including what questions to ask him, see the article on choosing the
There are different models, sizes and efficiency’s available on the market. The type of unit, for example, a split system versus a single-packaged
unit, may depend on the region of the country you live in and the type of home you live in (e.g., basement house, slab foundation, crawl space, etc).
Regardless of the type of central air conditioner you install, the size and efficiency can have the most impact on your costs.
Air conditioner sizes, also referred to as cooling capacities, are measured in British thermal units per hour (Btuh). One ton is equal to 12,000 btuhs.
A unit that has too little capacity may not keep the whole house cold, while an over sized unit will cost more and be more expensive to run.
The most expensive part of an air conditioner to replace is the compressor. Air conditioners typically feature a scroll or reciprocating compressor,
depending on the unit size and efficiency. Check to see if the compressor has an additional warranty (e.g. 10 year compressor warranty), separate
from the standard cooling system warranty.
Finally, if you are gone during long periods of the day (or night) invest in a programmable thermostat. With a programmable thermostat, your cooling
system can use less energy while your gone and then adjust itself so the house temperature is comfortable when you arrive.
And if you are wondering whether you should turn off the air conditioner so you can open a window to enjoy a break in the warm weather, here is
some advice: do not continually turn on and off your air conditioner to adjust to the changing warm weather patterns outside. If you want to open a
window to get some fresh air, it is better to leave your air conditioner on rather than turning it off. If the inside of the house gets hot and you have to
turn the air conditioner back on then your air conditioner has to work harder to cool down your house and everything in it.
Professional cooling contractor tips to consider before you buy
What over 500 surveyed contractors say…
A top leading consumer magazine recently surveyed over 500 contractors and reported the following tips on purchasing a central air-cooling system.
Choose the right-sized air conditioning system. If it is too small, then it won’t cool properly; if it is too large, then it won’t dehumidify properly.
Beware of replacing only one of the two main components if shopping for a replacement system. Replacing only the indoor or the outdoor unit
of a system may result in a mismatch that compromises efficiency. Contractors also said these systems are more repair-prone than systems
where the two units have been bought and installed together.
Look for an experienced contractor. One-fifth of the contractors surveyed said the primary reason for their service calls was improper
application or incorrect installation.
Maintain your system properly. At least 40 percent of surveyed contractors said that service calls were primarily the result of improper
Seasonal Heating and Air Conditioning Tips
Help your heating and air conditioning products run smoothly during the seasons you need them most.
What you can do:
Follow the manufacturer’s maintenance instructions which generally include these instructions:
Keep air-supply outlets and return inlets clear of obstructions.
Clear leaves, brush, and dirt as they accumulate on the outside unit.
If there’s a pipe for draining condensate water, check it for blockage.
Check the air filter once a month during the operating season. Replace it if it looks dirty (some are washable).
Routinely have a professional contractor, such as our Service Pros, perform a pre-season check-up.
Consider purchasing a maintenance agreement, especially if it includes both cooling and heating systems. A plan may allow the contractor to
spot problems before they lead to a breakdown. You also may receive priority service, which is handy when you are living in the sweltering
heat. (See below for details of what the agreement should include)
Invest in a digital thermostat to program temperatures for your cooling system to follow throughout the day. For example, if no one is home
during the day, a programmable thermostat can run the air conditioner or furnace at a temperature that will require less energy, then the
program can adjust itself to a temperature to your liking one hour before you come home. Ask your contractor if a digital thermostat is right for
What a Maintenance Agreement should cover
A seasonal check-up should include the following items for Air Conditioning or Heat Pump:
Clean and adjust thermostat
Check voltage and amperage to all motors
Check air flow across the indoor cooling coil
Lubricate all moving parts (unless permanently sealed)
Check air filters
Check air flow across the outdoor coil
Check indoor fan relay
Check compressor contactor
Check electrical wiring and connections
Check that condensate drain is open
Check indoor coil
Check operating pressures
Check temperature drop across indoor coil
Check indoor coil super-heat
Check outdoor sub-cooling
Check reversing valve (heat pump only)
Check defrost control (heat pump only)
Check outdoor coil
The cold winter months can also be busy for professional heating contractors. Two very good reasons for having a professional check your unit before
the heating season is prevention of a breakdown and ensuring safety from harmful gases. A check-up can save you time, money and keep you
comfortable during the coldest days.
A seasonal check-up should include the following items for gas or heating unit:
Clean and adjust thermostat
Check voltage and amp draw
Check air filters
Check fan-limit switch
Check electrical wiring and connections
Check temperature rise across heat exchanger
Check firing rate
Check gas manifold pressure (gas only)
Check for leaks
Change nozzle (oil only)
Change filter (oil only)
Tips for selecting a contractor
The following tips can help you make an educated decision and receive quality service:
Ask for a certified HVAC technician. Keep in mind that not all states require certification.
Your contractor should be licensed, well trained, and experienced to provide quality installations. Ask your contractor about his or her training,
experience, and membership in contractor associations. Ask if he is insured and bonded.
Good contractors own and use refrigerant recovery equipment and are certified to handle refrigerant in cooling systems. Ask for proof of
certification if applicable to your state.
Contractors should know how to properly size your home heating and cooling system (e.g., determine whether you need a two-ton or three-
ton cooling system). Don’t use a contractor who wants to size your unit solely on the square footage of your house. Contractors should
calculate equipment size using computer software or professional guidelines such as the Air Conditioning Contractors of America’s “Manual J.”
To gather necessary information, the contractor should spend at least a half hour poking around your house, taking measurements, and asking
questions. He or she needs to measure ceilings, floors, windows, and walls, and check insulation throughout the home. Systems that have been
sized properly to fit your home provide better humidity control, cycle on and off less frequently, and cost less than oversized systems. Insist on
getting a copy of the load calculations (or computer printout). These can be useful for comparing bids.
Ask your contractor to inspect your ducts for leaks, incomplete connections, and compatibility with the rest of your system. Ideally, your
contractor should use diagnostic equipment and fix leaks using a quality duct sealant (duct tape is not sufficient). He or she may also
recommend changes to your duct system. Since as much as 30% of the efficiency of your system is a result of your duct work, overlooking
duct improvements may compromise comfort and cost you money.
If your house or water heater uses combustion (i.e., it burns something like natural gas or fuel oil), you should have a house pressurization test
performed to make certain there is no danger of “back drafting.” Back drafting is when the fumes from the combustion process are pulled back
into the home, threatening the health and safety of occupants.
Your air conditioner or heat pump condenser should always match the indoor coil. Your contractor should replace both coils at the same time
for maximum efficiency.
Have your contractor select an install location that provides for ease of maintenance. Make sure the inside coil can be reached for cleaning.
Depending on the model, the contractor may need to install an access panel. The coil should be cleaned every two years. The air filter should
also be easy to remove and should be cleaned or changed whenever it is dirty. (This can be monthly during peak season.)
If possible, have the contractor place outside air conditioning units on the north or east side of the house, out of direct sunlight. Leave plenty of
room for free air flow on all sides, and at least four feet at the top. Keep the area free of debris and shrubbery.
Always obtain a written contract or proposal before allowing your contractor to install a new system and be sure to ask about warranties.
Remember, the contractor who gives you the lowest bid may not be the best choice for you. Paying slightly more may get you better equipment
and better service. Carefully evaluate a contractor’s proposal to ensure you get the equipment and service that best meets your needs.
Most contractors offer maintenance agreements to keep your system running smoothly for years to come. Also ask about the warranty length,
what it covers and if there are extended labor warranties available.