Consumer buying tips

Central Cooling Systems

What consumers should know before they install a central cooling systems.

With summer heat underway, 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 ductwork 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 oversized 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 right contractor.)

There are different models, sizes and efficiencies 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 oversized unit will cost more and be more expensive to run.

A unit’s energy consumption is rated in SEER (seasonal energy-efficiency rating). The higher the SEER rating the less energy required to run the unit. The Department of Energy standards are currently a minimum of 10 SEER for central air conditioning units. The ratings can range from 10 to 18 SEER. Units with a 10 SEER rating are typically installed in new homes and as replacement models. According to a survey of over 500 contractors, a rating from 11 to 14 are mostly recommended because they are the least expensive to own overall and require the least repairs. While a 10 SEER unit initially costs less (maybe by a few hundred dollars) your monthly electric bill will be on the average $5 more compared to that of a 12 SEER unit. (Higher savings occur in the south, while northern regions may have little savings.) Additionally, some utility companies offer rebate programs to those with higher efficiency units installed.

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.

Contractor Tips

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.
  
• Invest in a 11-14 SEER model. 11-14 SEER are recommended for their combined performance in increased energy efficiency and product reliability.
  
• 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.
  
• Think twice about buying a zoned system. Contractors said that zoned systems (which alter airflow to different zones in the house) require more cooling-equipment repairs than regular systems.
  
• 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 maintenance.

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. Most plans include two pre-seasonal check-ups and cost about $80 to $200. 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 you.

What a Maintenance Agreement should cover

• A seasonal check-up should include the following items for Air Conditioning or Heat Pump:
  1. Clean and adjust thermostat
  2. Check voltage and amperage to all motors
  3. Check air flow across the indoor cooling coil
  4. Lubricate all moving parts (unless permanently sealed)
  5. Check air filters
  6. Check air flow across the outdoor coil
  7. Check indoor fan relay
  8. Check compressor contactor
  9. Check electrical wiring and connections
  10. Check that condensate drain is open
  11. Check indoor coil
  12. Check operating pressures
  13. Check temperature drop across indoor coil
  14. Check indoor coil super-heat
  15. Check outdoor sub-cooling
  16. Check reversing valve (heat pump only)
  17. Check defrost control (heat pump only)
  18. 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:
  1. Clean and adjust thermostat
  2. Check voltage and amp draw
  3. Lubricate motors
  4. Check air filters
  5. Check fan-limit switch
  6. Check electrical wiring and connections
  7. Check temperature rise across heat exchanger
  8. Check firing rate
  9. Check gas manifold pressure (gas only)
  10. Check for leaks
  11. Change nozzle (oil only)
  12. Change filter (oil only).

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