Sizing Air Conditioners

When the sum­mer heat sets in, you will be rely­ing on your air con­di­tion­er to keep you cool and com­fort­able. Just remem­ber, don’t over­do a good thing!

Stud­ies have shown that one-third of home air con­di­tion­ers do not work the way they should because they are over­sized. And an over­sized air con­di­tion­er does not mean more cool com­fort for you; it means high­er pur­chase costs, high­er oper­at­ing costs and a home that is too cool to be com­fort­able.

An over­sized air con­di­tion­ing unit short-cycles (runs for short­er peri­ods of time than it should) and uses more elec­tric­i­ty than a prop­er­ly sized unit. Air con­di­tion­ers oper­ate more effi­cient­ly the longer they run con­tin­u­ous­ly. They should be sized so they do not turn on and off fre­quent­ly on hot days. An over­sized air con­di­tion­er that runs for only short peri­ods of time makes your house uncom­fort­able because it can­not dehu­mid­i­fy the air effec­tive­ly. The indoor coil nev­er gets cold enough to do its job of remov­ing mois­ture from the air. That means an over­sized unit will leave your home cold and clam­my, espe­cial­ly when the out­door air is humid.

Over­sized air con­di­tion­ers cost more to buy and do not last as long. Do not pay extra for an air con­di­tion­er that is too big for your house; the larg­er sys­tem will cost you hun­dreds of dol­lars more and give you few­er years of ser­vice.

Con­trac­tors should cal­cu­late how much cool­ing a home needs accord­ing to guide­lines such as the Air Con­di­tion­ing Con­trac­tors of Amer­i­ca’s Man­u­al J. A con­trac­tor should not size your unit sole­ly on the square footage of your home. To gath­er the infor­ma­tion nec­es­sary, a con­trac­tor should spend some time pok­ing around your home, tak­ing mea­sure­ments and ask­ing ques­tions.

Do not be tempt­ed by the low­est bid. Be will­ing to pay for the time the con­trac­tor must spend to do the job right.

If you are con­sid­er­ing replac­ing your air con­di­tion­er, buy a high effi­cien­cy unit. Cen­tral air con­di­tion­ers are rat­ed by SEER, or Sea­son­al Ener­gy Effi­cien­cy Ratio. Klick­i­tat PUD rec­om­mends air con­di­tion­ers with a SEER of 11 or high­er to get the best ener­gy effi­cien­cy.

You should also con­sid­er installing an ener­gy-effi­cient heat pump sys­tem. They pro­vide year-round com­fort – even, com­fort­able heat in win­ter, and cen­tral air con­di­tion­ing in sum­mer.