Air Conditioning Terminology
Tons of cooling - Capacities of air conditioners are rated in tons of cooling. One ton of cooling is equivalent to 12,000 BTU's.
SEER rating - This term is used to identify the efficiency of the unit. It stands for Seasonal Energy Efficiency Ratio. The higher the number the more efficient the unit.
Two Stage - Some AC units are equipped with two stage compressors or dual compressor systems. This allows the unit to run at a lower capacity during mild days and to maintain steady temperatures throughout the day. This is an excellent option for Colorado as a lot of the days of summer don't require a large capacity unit.
Split system - An air conditioning setup that is comprised of an evaporator coil installed on an air handler or furnace and a condensing unit located outside. These components are connected with copper piping in which refrigerant flows. The split system is the standard for residential air conditioning here in Colorado Springs.
Condenser - This is the part of the AC system that is located outside. It contains the condensing coil, compressor and some electrical controls.
Evaporator - This is the coil that is installed on your furnace. It is normally placed on the discharge side of the blower assembly.
Refrigerant - The gas that is used to carry the heat from in your home to the outside.
R22 - A refrigerant that is slowly being phased out of production. It is an HCFC (Hydrochlorofluorocarbon) refrigerant that is harmful to the Earth's ozone layer and a contributing factor to global warming.
Air Conditioning Operation & Theory
1. Thermostat calls for cooling.
2. Furnace blower comes on.
3. Compressor and
4. condenser fan are engaged.
5. Liquid refrigerant is pumped to evaporator.
6. Liquid is released into evaporator coil and starts to boil off by absorbing heat from the passing air. The air is cooled and excess moisture condenses on coil and drains out condensate drain.
7. Gas returns to compressor and is compressed to hot gas.
8. Hot gas is cooled to liquid state and cycle starts over.
9. Thermostat becomes satisfied.
10. Compressor and condenser fan shut off.
11. Indoor blower shuts off (may have a delay).
Be sure your air conditioner is sized correctly. Air conditioner capacity is very important. Both undersized and oversized AC can be uncomfortable and frustrating. An undersized AC will have trouble providing the necessary cooling during the hottest days of summer. And oversized units can cycle on and off quickly compromising humidity removal which is crucial for proper indoor comfort. Operation problems such as coil icing can also occur contributing to inefficient and costly performance.
Two stage air conditioning systems are a great option, providing the right size unit at all times. Air conditioning capacity is determined by your home's construction, size, and orientation to the sun. A procedure called a Manual J Heat Loss/Gain calculation can be performed to accurately determine the proper size of air conditioner needed. In some instances the AC size may be restricted by the furnace blower size and the duct system. Unfortunately some duct systems are minimally sized for heating purposes only (an unfortunate consequence of the low bid philosophy of some builders). In these cases in order to install an air conditioner, you may have to accept certain limitations in its performance or be prepared to do some duct modifications. Some two-story homes with poorly designed duct systems, as an example, have in our experience proved to be occasionally problematic. The condensing unit located outside requires a 220 volt dedicated circuit from your breaker panel. If your panel is full or overloaded, additional electrical modifications may be necessary.
SEER ratings range from 13 to 21 with higher ratings available in very high end equipment. Equipment with higher efficiencies tend to have better control systems, are quieter and and have longer warranties. SEER ratings do not affect capacity--only operation cost.
It costs approximately 12 to 30 cents to operate most residential air conditioners. Considering that most Colorado nights are fairly cool, air conditioners will only run 4 to 8 hours on the worst of days. This will result in a reasonable cost of only 30 to 60 dollars per month for the cool comfort of central air conditioning.
R22 & R410A refrigerants are used by air conditioners at this time. According to the Montreal Protocol that was agreed upon by most international countries HCFCs ,which R22 is, will be phased out up to the year 2030. In 2010 all residential central air conditioning equipment will use R410A refrigerant. For the next 20 years or so R22 will still be available but, most likely, at a steadily increasing cost.
