Helpful Cooling and Heating Tips and Information

SEER Rating
Two Stage vs Single Stage Air Conditioning
Furnace and Air Conditioner Diagram

SEER Rating

As with anything having to do with energy conservation SEER is probably the least understood concept, both by homeowners and contractors. Simply put, SEER stands for Seasonal Energy Efficiency Ratio. The resulting number that is applied to an air conditioner is called it's SEER rating. The higher the SEER rating the more energy efficient a given air conditioner is.

SEER is simply a formula that is described by the outcome of the following:
Divide the system's rated Btu's by it's stated SEER rating to determine how many watts it consumes per hour, (Kwh stands for kilo-watt hour).
Here's the formula (we'll use a 3 ton, 15 SEER system for this comparison):
36,000 Btu's (3 tons) divided by 15 SEER = 2400

Using this basic formula, you can calculate the kilo-watts per hour used by each air conditioner unit.

Below is an example of operating costs for a 2.5 ton air conditioner over 5 years with an electric rate of $.12 per kilowatt hour. Please note: There are new regulations regarding the efficiency standards. Please look at the effieciency standards here.

Two Stage vs Single Stage Air Conditioning

The primary difference between the single-stage and the two-stage air conditioning unit is the number of pistons used to move air through the cooling fins and into your home.

With a single-stage AC unit, you have a single piston and the two-stage air conditioning unit has two pistons. Two pistons allow the two-stage system to move air faster – one piston runs during milder temperatures and both pistons run when the temperature is very hot.

A two-stage air conditioning system is more energy-efficient and better at maintaining a narrow temperature range and it will save you money on your utility bill.

A two-speed air conditioner or heat pump compressor has two levels of operation: a high setting for the extreme heat of summer and a low setting for more moderate days. The two-stage low setting will work for about 80% of your home comfort needs. Two-stage systems run for longer periods of time, they also provide a more even temperature for your home, and will be more energy-efficient.

A single-stage air conditioner will initially be less expensive, but will be more costly to operate over the life of the system. With a single-stage unit you are never truly comfortable since it is either on or off. Each time the unit starts up it is costing you more money due to the extra energy needed for start up. Since this start up phase is repeated frequently during the hottest days of summer the operating cost is greater.

Two-Stage Air Conditioning System Benefits:

• The 2 stage AC equipment gives improved temperature and humidity control during the day for variances in cooling demands.
• Two-stage AC units are more likely to run continually, though at a much lower rate of motion than the single-stage system and provide more even comfort for your home.
• The two-stage system will cost you less to operate because it is more energy-efficient, which means greater savings on your electric bills over the life of the unit.

Single-Stage Air Conditioning System Benefits:

• Single-stage systems generally cost less than two-stage AC systems
• The single-stage system has less complex electronics, which could mean fewer repairs and less expensive repairs over the life of the system.
• Under certain circumstances, the single-stage system may dehumidify your home more efficiently.

Furnace and Air Conditioner Diagram

Below you will see a basic diagram of how a furnace and air conditioner are installed. The diagram shows a standard upflow system and your system may be set up differently, however this should aid you in knowing the various components of a standard system.