Did you know that one third to one half of home air conditioners don't work as well as they could because they are oversized. Be careful when dealing with contractors, because they can size air conditioners at least a half ton larger than necessary, and often oversize by a ton or more. It's important to note that we are not talking about the weight of the air conditioner, instead we are talking about the tons of cooling (One ton of cooling is equivalent to 12,000 Btu).
Also an air conditioner that's oversized turns itself on and them off more often than it should, as a result you pay more for it because it raising your utility bills by using more energy. Oversized units will also not dehumidify the air as well as a smaller system would. Don't forget about the increase in noise, So remember an oversized air conditioner doesn't mean more cooling, it means higher, costs and lower comfort.
So how do you make sure that your contractor sizes your air conditioner properly?
Well, you need to ask your contractor to use the sizing manuals put out by the Air Conditioning Contractors of America (ACCA). ACCA Manuals J and S help contractors size and select equipment. The contractor should measure your home, take note of where the windows are, the direction of the home, and insulation levels. All these measurements should then be entered into formulas that to calculate the amount of cooling your house needs.
Another important thing to consideration when selecting a central air conditioner is the ability of the unit to remove moisture from the air. Keep in mind the different units handle moisture differently.
Some other tips when dealing with contractors:
- Get a copy or printout of the cooling load calculations, because these can be useful in comparing bids from different contractors.
- Ask your contractor to size the air conditioning unit based on the latent cooling load (which takes into account the humidity of the air) and the sensible cooling load (which takes into account the temperature of the air).
- Don't only consider the lowest bid, you have to be willing to spend more to get the job done right.
