Air Conditioner Proper Fit?
We’ve mentioned in prior Blog posts and social media articles the importance of having an air conditioning system that properly accommodates the size of your home or business building. Why is this so important?
We’re not talking about a system’s physical dimensions, but, rather, its ability to produce cooled air.
A/C 101 Explains Differences
The air conditioner’s ability to produce cooled air is measured in BTUs (British Thermal Units) per hour and in tons.
- A BTU measures heat output. One BTU equals the amount of energy needed to raise one pound of water by one degree F (Fahrenheit). One ton is the equivalent of 12,000 BTUs per hour, or the amount of energy it takes to melt one ton of ice per day.
- Logic might say that if a 3-ton unit does a ‘good’ job of cooling, then a 4-ton would do a ‘great’ job. This is a common misconception. Here’s an example. In the 1980’s very large units were used to cool massive entertainment centers quickly. Electricity was far less expensive back then and insulation was poor. This quick cool method could reduce the temperature of the entire place in about 15 minutes, then shut off. But the heat would quickly return and on the system would go. This constant on and off cycling cost big in electric bills and repair dollars.
This concept holds true today in homes as well as large buildings.
On the other hand, if your system is too small, it will run continuously, trying to keep up with the infiltrating heat from outdoors. Again, this will run up your utility bill and wear the unit out in no time.
Knowing the Right Sized Air Conditioner for Your Home
If you’re the type of person that likes to have some insight into these decisions, here is a quick rough estimate:
- (Square footage times 25, divided by 12,000) – 0.5 = required tons. So a 1,500 square foot home would calculate like this:
- 1,500 X 25 = 37,500
- 37,500 / 12,000 = 3.1
- 1 – 0.5 = 2.6
Thus, you would need a 2.5 to 3-ton central air conditioning system.
But there are other variables to consider.
- The type of climate where your home is located.
- The comfort level of your family, your habits, humidity, and air quality.
Let’s talk about comfort. This is what you want as the unit lowers the temperature, and removes moisture from the air. To do this, the unit can’t be frequently turning on and off, which will happen if the system is too large for the space you occupy.
- This is how it works. As air passes over the evaporator coils, it encounters a very cold surface. The temperature drops. In places where there is high humidity, the dew point must go lower, leaving water vapor condensate on the coil. This happens on over-sized systems as well, but not efficiently enough to handle the humidity.
If you live in a dry climate (which we don’t have here in Minnesota) this is not a problem. But in humid areas, the above scenario causes the motor to keep turning on and off, again wearing out parts and costing money.
A/C 101 for Buildings
Now we’re talking about a sizable expense, but keep in mind that improving employee comfort can improve employee production. Despite the potential investment costs in upgrading a current unit or units, it’s of utmost importance to determine what size system best fits the building space.
- As with a home system, a building unit that is too large will not adequately cool an area, plus the air flow might become restricted if the ductwork is not correctly sized.
The number of BTUs, or tons, again can be roughly calculated. This is done differently for a work space vs. a home air conditioning system.
- Decide the square footage of the area to be cooled. (If the business is divided into zones to be cooled separately, calculate them individually.)
- Multiply each square footage per area by 25
- Add 400 for each person who works in that particular area.
- Add 1,000 for each window in that area.
(Note: These calculations are for rooms with 8-foot ceilings. Higher ceilings require higher numbers of BTUs to do the cooling job.)
Not really, and keep in mind, this is A/C 101 – an overview of what to expect when a HVAC technician evaluates your home or business needs. He’s the expert.
But take for example you do the math above and come up with a figure. The next step is converting these calculations to tons. Now you’re talking about the big boys like 9,001 to 10,000 Sq. Ft. and 225,025 to 250,000 BTUs/Hour, requiring perhaps 15 to 16 ton systems.
Not to mention the other factors considered like the number of windows, doors and the expected people sharing the space.
Perhaps you’ve learned more than you ever wanted to know about how important it is to get the size system that will work optimally in your home or business. To ignore some of these things can ultimately end up in very high energy bills and equipment breakdowns.
With summer upon us, don’t risk your family or employees comfort, or the loss of valuable production time.
At Abel we have technicians with the expertise to answer your questions and give you the best evaluations when considering installing new A/C equipment or testing and maintaining your present system.
Give us a call at 952-472-COOL (2665) or Contact Us