Are We Wasting Energy More Efficiently

Are We Wasting Energy More Efficiently?

Record electricity consumption, rolling blackouts, and brownouts.... Have you ever thought that maybe equipment efficiency levels aren't the whole problem? In fact, a study prepared for the (EPA) in consideration of the changing EnergyStar� labeling revealed that 74 percent of central air conditioners and heat pumps have an improper refrigerant charge and 70 percent have air flow lower than 350 cubic feet per minute per ton (cfm/ton).

Good news: Congress is again rewriting new laws to make heating and cooling equipment more efficient! Once more, they are living in a vacuum - They have no clue that fixing our present inefficient installations with the existing equipment will greatly reduce our energy problem. They would rather force the consumer to pay more money for a bigger number on the box, and again get nothing accomplished. Thanks to ACCA this new law is back in Committee (Aug 2007).

Another fantastic article published in the

HVACR NEWS (the HVACR weekly news magazine). This one by Jim Bergman, June 26, 2006 edition.

Again I have compiled, and condensed the article for space, our non technical audience and I have added my experience and comments.

Wayne W. Mulholland

Operations Manager

That means 7 out of 10 systems installed today have problems that directly effect their capacity and efficiency. Even purchasing a system with a higher SEER level will just help us waste energy more efficiently. Some field technicians have somehow forgotten, or maybe never learned, the delicate balance between airflow, refrigerant charge, cooling capacity and efficiency. Only two things can be adjusted on a standard residential system; air flow and refrigerant charge. Air flow is critical to the proper operation and capacity of all air conditioning systems. If the airflow is compromised in any way, the equipment cannot achieve it's rated capacity.

Capacity is a the key word. There are 12000 Btu's in one ton of refrigeration. But, in order to produce one ton of cooling capacity we require a minimum of 350 (CFM) Cubic Feet per Minute of air flow. - All air conditioning systems are designed with an optimum 400 CFM. - A true 3 ton system therefore produces a cooling capacity of 36,000 Btu's with the required 1200 CFM (Or 1050 CFM minimum) air flow. Consumers are not aware of many of the conditions required to cool their homes or how an air conditioning / heating system works; and why should they be? We each have our own profession that we are familiar with, gain knowledge in and rely on for our lively hood. This is why we created our Consumer Information series of literature.

Let's take an example: Two pick up trucks, both marked on the fender "1500", both are white, both have the same cargo bed, both are extended cab. Are they both the same? Are you sure they have the same motor? - transmission? capacity? - interior appointments? - etc. How can you tell the difference in value without knowing these things?

All new systems today are rated by (SEER) Seasonal Energy Efficiency Ratio, (EER) Energy Efficiency Ratio and Cooling Capacity by the (ARI) Air Conditioning and Refrigeration Institute. The consumer site is : http://www.ari.org/ When looking for the efficiency of a system, you will find that they are matched sets of condensers, coils and furnaces for each manufacturer. Each manufacturer also has options for more efficient systems if say a gas furnace is matched with a specific coil. But, there is no rating for a mis-matched system from different manufacturers, (such as a Carrier condenser and a Trane furnace) and different systems from the same manufacturer can have different efficiencies depending on the match-up selected.

A technician may tell you that you need a new air conditioner. He then inquires about the size of your home. You tell him it is about 1400 square feet. His response is that you need a 3 1/2 ton system. (His math is 1400 square feet divided by 400 sq. ft. per ton equals 3.5) or maybe he used 500 sq. ft. per ton. Then he would have told you a 3 ton system will work. Or maybe he plans on replacing your old system with the same size 15 SEER, which we all know is MORE efficient. There are (2) TWO additional very big red flags that have been raised here:

FIRST - Which method is correct? 400 sq. ft. per ton or 500 sq. ft. per ton? The answer is - They are both wrong!
The proper method of sizing a replacement air conditioner is with an ACCA approved Manual J, or equivalent Heat Load Calculation that considers window size, number of occupants, appliances, our Texas 100 degree days, ceiling height, home construction and many other factors.

SECOND - Where in this 400/500 square foot thing did he mention CAPACITY? Did he offer to present an ARI report with the installation?

Additionally, what is the RATED CAPACITY for the specific piece of equipment for the heat load generated with the number of occupants, appliances and our Texas 100� F days? Improper air flow and refrigerant charge lead to decreased comfort, higher humidity, low capacity, excessive electronic consumption and shortened equipment life. Before condemning even an older system because it doesn't cool properly, it is important to check and correct any air flow concerns. Correcting the air flow is an absolute necessity when installing a new system.

Air Conditioners remove both heat and humidity in a specific ratio, which is critical to achieve comfort. Usually 72-78 percent of the rated capacity removes heat and balances the humidity. Systems with low air flow have good humidity removal but run longer to reduce the temperature. Systems with high air flow remove the heat but not humidity, leaving the home cold and clammy.

One more thing about CAPACITY. If your air ducts are leaking, part of your capacity is being used to cool the attic.