AIR CONDITIONERS 101

Understanding A/C efficiency:  Air conditioners are rated by SEER (Seasonal Energy Efficiency Ration).  For every one SEER increase, electricity usage is reduced roughly 10%.  As a ratio, this percentage decreases as the SEER rating rises above 10 SEER.  Houses built prior to 1992 would normally have a/c's with ratings of 7-8 SEER.  In 1992 the EPA set the minimum allowed at 10 SEER.  In January 2006 that minimum was raised to 13 SEER (making most of today's equipment appear "obsolete").

Today's standard efficiency 13 SEER a/c units use about 23% less electricity than a 10 SEER unit (produced in 1992 - 2005), and about 46% less than a 7 SEER unit (units produced prior to 1992).

SEER ratings:  The outdoor a/c unit, by itself, has no efficiency rating.  The outdoor a/c unit carries an efficiency rating (SEER) only after it is determined which indoor cooling coil it will be matched with (in the same way you don't know a car engine's mpg rating until you know which auto body it will be placed into).  An outdoor condenser may have 25 different SEER ratings when matched with 25 different indoor coils.  It is common for a manufacturer to take the highest rating number possible for an outdoor condenser, then use that number in the unit's name.  For example, an outdoor unit titled "XD15" may have ratings of 13 TO 15 SEER depending on which indoor cooling coil it is matched with.  The XD15 suggest you are getting a 15 SEER unit, while in reality the contractor may be using a coil (because of space limitations) that will actually give a rating considerably less than 15.  This practice is misleading, and all too common.  When a homeowner is told a unit is "15 SEER", rounding up is probably taking place.  Be sure you know the exact SEER rating with the particular indoor cooling coil being used.

FURNACES 101

Understanding gas furnace efficiency:  Gas furnaces are rated by AFUE (Annual Fuel Utilization Efficiency) as a percentage.  The % indicates how much of the furnace's heat goes into the house, vs. how much heat goes up the exhaust flue (the higher the % the better).  Prior to 1992 most furnaces were about 60% AFUE.  In 1992 the EPA set the minimum allowed at 78%.  Today, most furnaces come in either of 2 efficiencies: 80% or 90+ %.  The added cost of a 90+% furnace (usually $1,300 - $1,500), and our short and mild winters, make the 80% furnace the most common choice here in the south. 

Single-stage heating vs. two-stage heating:  After determining the efficiency of a gas furnace there is another fundamental choice, whether to go with a single-stage furnace with a standard multiple-speed blower motor or to go with a two-stage furnace with a variable speed blower motor (such as the Lennox SL280V or EL195E). 

Two-stage heating

- provides regulation of heat output for greater temperature control and more even heating.

- Includes a two-stage thermostat (if new wire can be run).  In this scenario the thermostat reads the temperature and determines when the furnace will operate on low or high fire.  We find that many of our competitors use a single-stage thermostat so that they won't have to run a new wire.  In such cases the furnace timer is used to switch the furnace from low to high fire after a few minutes of operation.  With the single-stage thermostat temperature control is sacrificed.

Variable-speed motor

- automatically adjusts the control of airflow for ultimate comfort.

- uses about half the electricity of a traditional motor.

- increases efficiency of air conditioner-- reducing electrical usage.

- Variable speed motor offers better humidity control.

- Quietest furnace available (according to independent lab test).

- 10 year parts warranty.

-  When installed with a complete system, we give a 10 year parts warranty to the a/c too.

Solving Home Comfort Problems

Q. I have a tri-level house with one heating and cooling system.  The temperature varies on each floor.
A. This is a common problem; heat rises and cold air falls.  Moreover, the thermostat is usually located in the heart of the house, usually on the main floor, which does not experience the temperature extremes of the other floor(s).  The thermostat satisfies more quickly shutting the system off.  This state deprives the other floor(s) of much needed conditioned air.  To help remedy this problem try leaving the fan on at the thermostat, close the downstairs registers in the summer to push the cool air up and close the top floor registers in the winter to push the heat to the lower floors.  Reducing the size of the system will also cause it to run longer for more even temperatures.

Q. My house is too humid in the summer.
A. Make sure air conditioning has a clean air filter and has a proper refrigerant charge.  A central dehumidifier will remove a large amount of water from the air.  An appropriately sized air conditioner will help remove more humidity.

Homeowner Trouble Shooting

Q. My system does not heat or cool well. 
A. Check the air filter, make sure the registers are open, remove objects blocking return and supply air openings, make sure the air conditioner outside is free from bushes and trees and have the equipment check by a professional.

Q. My air condition or heater does not come on at all.  The fan does not even move air. 
A. Check the breaker box.  If you have recently changed your filter make sure the furnace switch has not been turned off and make sure the blower door has been put back properly.

Miscellaneous

Q  My basement is musty and cold in the summer. 

A  This might be due to ground source water.  If this is the case call a water abatement expert to assess your basement.  If your basement shares a system with the main floor you might try leaving the fan in the on position so that the blower will mix the air on the two floors all year long.  This will mix up the air between floors. A whole house humidifier that is directed specifically to the basement will help keep it dry.