If you’re going to buy an air conditioner unit this summer, remember to pick the right size. [Energy Star]


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  1. backbroken says:

    Big enough to cool your apartment, small enough not to ignite the hoarded fuel in the closet?

  2. SexCpotatoes says:

    I wonder if the apartment insurance will pay to replace the gasoline.

  3. B says:

    If by right size, you mean the largest I can afford, then I agree.

  4. e.varden says:

    I call horseshit on this. A “too big” A/C can always be turned down to function like a smaller one, by adjusting fan-speed and desired temperature result.

    A 10K BTU unit can be made to run almost constantly un a small room, thus wicking out humidity just like a 5K one.

    IF however, the temperature soared, there’s nothing more you can gain from the 5K unit

  5. Myotheralt says:

    So, size does matter.

  6. PatrickSF says:

    A “too big” A/C leaves you feeling cold and clammy, as it cools the air faster than it can dehumidify it.

    The “conditioning” part of “air conditioning” involves more than just extracting heat.

  7. DionneAegialeia says:

    I un-call horseshit. Hit don’t work that way, mate. Not that I’m zackly sure
    what you are trying to say with “by adjusting the fan-speed and desired
    temperature result.” A big unit will shut down the compressor at whatever
    temp you have it set at, but even if the fan continues to run it isn’t
    removing any more humidity, and won’t until the compressor comes back on and
    cools the coil again. A smaller unit runs the indoor air over the coil more
    times before the room gets to the temp preset, removing more moisture. More
    passes, more water removal. No amount of fiddling with the controls of a too
    big air conditioner will change that. You’re right about the last part
    though, if it ain’t big enough, it ain’t big enough.

  8. @myotheralt:

    Only matters to other people. So says my wife.

  9. Maurs says:

    No, no, if it’s too much A/C for the space you are cooling it won’t dehumidify the air properly. It will be cold, yes, but it will still be moist, and it will suck balls.

  10. FLConsumer says:

    There is the possibility of oversizing ACs…BUT, with variable-speed blowers, just run the fan on the lowest setting and you’ll get more dehumidification and quieter operation from the window AC. As long as it’s not grossly oversized, you’ll be fine.

    With central ACs, it’s a whole other ball-game, and the majority of the contractors in the US honestly don’t understand the principles of humidity and refrigeration. With those, unless you’ve got a contractor who has no fear MAKING an AC system from scratch (spec’ing and selecting individual relays, compressors, coils, etc)rather than just selling complete boxes (air handler/furnace + outdoor condensing unit), stick to getting things sized correctly. Tons of mold & mildew issues in the SE because contractors just push boxes (and oversize things) and don’t understand the equipment they’re pushing.

  11. FLConsumer says:

    Also, if by some chance you get a system with an inverter-driven compressor (VFDs), there really isn’t a way to “oversize” them, as long as the heat load calc lies between the system’s max capacity and lowest possible capacity.

  12. Difdi says:

    Here’s something I’ve been thinking of getting for a while – promises to reduce electric bills on the AC…


  13. gjaluvka says:

    Another consideration is if you are running the AC in a room of an already air conditioned house – I use one in a big bonus room that is above a garage, in the sun, and has only one AC vent, so it stays way too hot using just central air.

    So I closed the central air vent and use a window unit. But with the cooling from other parts of the house, I find that a 5K unit is more than enough – in fact, I ran in on level 4 of 10 yesterday on a 99 degree day and it was the most comfy room in the house.

  14. u1itn0w2day says:

    I have frequently have heard things like use a larger unit on a lower setting.Especially been told that about fans.Best thing to do with fans is buy a larger blade fan or ceiling fan and run them on lower speeds.

    With an over sized AC unit onething to remember about getting too cold and ‘clamy’ is that cold attracts moisture.An over efficient unit will cool things to the point where they will attract moisture/condsensation.That’s where you don’t want to over cool.

    I’d say the best thing to do is make sure the room is well ventilated.You want air to be able to circulate around the whole room.Piles of stuff restricting air flow won’t help.

  15. The Porkchop Express says:

    @u1itn0w2day: Also the clamy thing leads to mold. We all know how bad that can be.

  16. backbroken says:

    @Lo-Pan: Clam mold? Ewww!

  17. PhilipInWA says:

    ACS acquired my student loan from Wachovia (who also got bail out funds using my loan on their books). The amount is a little over $14K. Since I started paying on the loans years ago, my 68-dollar fee has been automatically withdrawn from my banking account monthly and sent to Wachovia. NOW, ACS says they acquired the loan. They, somehow added $100 to the amount and sucked away the first payment without my permission. Now they want me to resign an agreement. I will join a class action suit against ACS. I do not have any contracts with them and did not give them permission to double my payment. I am fighting this one.