Ive noticed units that are 115 v. at high EER's (energy efficiency ratio) such as 10.5 but they draw higher amps . And ive noticed 230 v. units of the same capacity at a lower EER such as 9.5 ... yet they draw as much as half the running amps that comparable 115 v. units do. Its my understanding that its amps that spin the electric meter, so, since i have both 115 and 230 volts available as a power source, which is going to use the least electricity in the example above ? thanks.
When buying a specific capacity Window A/C, do you want to buy something with a high EER , or, low running AMPS ?
Apr 09, 2009
4 Replies
At double the voltage you draw half the amps to do the same job. It actually is watts that makes the meter spin. With a few technical variants, multiply amps times volts to get watts. You will see that both A/Cs will draw about the same for the same specs, the more efficient one will draw less for the same cooling.
As EXT already stated the watts will probably be very similar.
220 may draw 7.5 amps on two legs where a 110 would draw 15. The true advantage of running the 220 is the wire size required. Your bill will be about the same on most units, but a higher seer number should be a more efficient unit. The better SEER comes from some variable such as larger coils, more efficient compressor, or some other factor.
Your electric meter is an energy meter...watt-hours (ie kilowatt- hours)
The way I choose an window a/c unit....I get the unit that has the btu/ hour rating I'm looking for & then the best EER (relative to price). I also consider the predicted usage....a higher EER will reduce operating cost but that should be balanced against initial unit cost.
Assuming both units have similar (identical) btu/hour capacities, then the unit will use ~ 9.5% less electricity to do the same job.
If you only run the unit 30 days per year & 10 hours per day but it costs $200 more than the 9.5 EER unit ....depending on your cost per kilowatt-hr, the payback period could be quite a while and the cheaper unit might make more sense.
You might save something on the order to $1 per day.
cheers Bob
Thanks everyone for the educational info. Much obliged.
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