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Serving Maryland and Washington, D.C.

Serving Fairfax and Loudoun Counties and the
surrounding area

Monday - Friday 7:30am - 5:30pm | Saturday 8:00am - 1:00pm. CALL FOR EMERGENCIES


Serving Maryland, Virginia,
and Washington, D.C.

Serving Maryland and Washington, D.C.

Serving Fairfax and Loudoun
Counties and the surrounding area

24 Hour Emergency Services, 7 Days a Week

Home of Mr. Heat Pump

B&B Air Conditioning & Heating Service Blog

AC Sizing: It’s Why You Need Pros to Install Your Air Conditioner


‘Tis the season to install a new air conditioning system! (Well, if you need one at least. If you aren’t sure, please call our technicians to ask them if an air conditioning installation in Fairfax, VA is something you should have done this spring.) With the summer weather not far away, now is a good time to take advantage of the relatively mild weather and go over your options to replace your old AC. And then take this simple quiz:

The easiest way to install a new AC is to…

  1. Do it yourself. There are plenty of online tutorials that make it a snap!
  2. Get Phil to do it. You know, Phil. That guy who says he can install anything as good as a pro.
  3. Call licensed and professionals HVAC technicians to handle the service.

The right answer is…

Of course, it’s #3. Far too much can go wrong when an amateur tries to install a central AC. This isn’t like popping a window unit in place. Not only is the labor more intense and complicated, but special calculations go into determining the size of the air conditioner. We’re going to look into the process of sizing an AC to show why professionals are vital for new system installation.

AC Size Is How Powerful the System Is

No, “size” isn’t how physically large the air conditioner is. It’s about how much cooling it can provide your home, as measured in the amount of heat it draws out. The basic measurement for an air conditioners size is tons of cooling, which is the amount of heat it takes to melt a ton of ice—approximately 12,000 BTUs. A residential home uses an air conditioner of 1 to 5 tons on average. And you absolutely do not want to get an AC that’s too large or too small.

The Problem With the Wrong Size AC

An undersized air conditioner is obviously going to create problems because it can’t cool down the house. But what about an oversized AC? Yes, it’s also a serious problem: the AC will begin to short-cycle, turning on and off multiple times per hour. This wastes power and will cause the air conditioner to fail early. And it won’t evenly cool down the house because it won’t stay on long enough.

Load Calculation 

So how do professionals know what size of air conditioner will hit the sweet spot for your house? They do what’s called a load calculation. They make an assessment of your home and factor together criteria such as insulation, number of rooms, room volume, number of windows and their facing, heat given off by lights and appliances, and how many people are in the house on average. They can put this data together and come up with the tonnage needed to cool the house without wasting energy.

Professionals are important for many more steps in the process, but getting this one right is critical: the AC simply won’t do the job expected from it if it’s the wrong size. So make sure you start out right and work with our team for your new AC installation.

Trust to B&B Air Conditioning & Heating Service: We are always there when you need us.

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