Let’s face it. It has been hot over the past few weeks. Really hot. Several of our clients have been asking for help in deciding what size air conditioning unit would best meet their needs. Trust me on this, one size does not fit all. If you meet an HVAC professional who tells you otherwise, or tells you what kind of air conditioning unit you need based solely the square footage of your home, run. RUN FAST! A trusted HVAC company should always perform what is referred to as a load calculation. You’ll need to be patient, these calculations take time. Be ready to carve out an estimated 2 hours on your schedule.
Is Bigger Better?
No. Plain and simple. Bigger isn’t better when it comes to air conditioning units.
If you buy an over sized air conditioner, it will reach the target temperature too quickly. This short-cycling behavior increases wear and tear, leading to premature breakdowns. Cycling on and off frequently also makes it impossible for the AC to adequately dehumidify your home, leaving you feeling cool but clammy.
If you buy an undersized air conditioner, the equipment may fail to keep up with cooling demand on hot, humid summer afternoons, even when running nonstop. This also increases your energy bills, despite your efforts to save money by purchasing a smaller system.
Forgive me for a moment while I get technical on you.
The cooling capacity of an air conditioner is measured in British thermal units (Btu). One Btu is about the amount of heat generated by a birthday candle. You’ll find window units with cooling capacities ranging from about 5,000 to 12,500 Btu, which indicates the amount of heat the unit can remove from a room per hour.
Central air conditioners are much larger, so they’re measured in tons, which is equivalent to 12,000 Btu. Most residential units range from 1.5 to 5 tons, or 18,000 to 60,000 Btu.
If you’ve ever wondered what size central air unit you need, or how to size a window AC unit, be aware that square footage is a factor. But square footage is far from the only consideration you should make.
- These additional factors also affect what size central air or window unit you need:
- Climate: A home in Michigan needs a smaller air conditioning unit than a house of the same size in Florida.
- Number of windows and orientation to the sun: South-facing rooms with a lot of windows heat up much faster and need more cooling power than north-facing rooms.
- Roof: What type of roof do you have - shingles or metal? What color is the roof?
- Basement: How far below ground is the basement?
- Home insulation levels and overall air-tightness: The better your home is at retaining cooled air, the smaller AC unit you need.
- Internal heat gain: If you use heat-generating appliances and electronics during the day, you need more air conditioning to counteract this heat gain.
- Occupancy: The more people who live in your home, the larger the AC should be.
If you are in the market for a new air conditioning system, any HVAC professional that comes to your home should be armed with questions. If he/she conducts the estimate like a fast-food drive through order, you know you’re not getting the service your family deserves. Aire Serv is here for you 24/7 to help solve your hot weather issues.