Please hope me keep cool AND entertained!

August 18, 2009 2:24 PM

Old building with old wiring + AC compressor = flickering lights. A question about electronics and possibly using an uninterruptible power supply to even out the electricity supplied to sensitive electronics. Details and question inside.

I live in an old apartment building in Chicago that doesn't have any kind of AC so window units are the norm. I was given a fairly powerful window unit as a gift (read: so can't exchange) to keep the large living room cool. It works really well and is perfectly sized for the room, but the power draw when the compressor kicks on causes the lights to briefly dim before the power draw stabilizes. The flickering doesn't bother me (but let me know if it's a dangerous sign, please), but I'm a little worried about keeping expensive electronics (like a stereo system and an LCD HDTV) plugged in with those power fluctuations. Unfortunately, fully half of the apartment is on this circuit, so it's not possible to just run a line to a different circuit. All we've got plugged in are 2 lamps, the overhead light, the entertainment center, and the AC. Even if it's just the lamps on, they still flicker when the compressor starts, so it's pretty clear that this AC compressor is just a tad too powerful for the circuit wiring as it stands now.

Which brings us to the meat of the question. The idea I'm toying with right now that might solve the problem is buying a UPS for the entertainment center so that the battery provides the extra power for the electronics when the compressor starts pulling on the room circuit. The only other solution to the problem (as the situation currently stands) that my googling has turned up is installing an AC compressor motor capacitor. That's a little too intense for something that's only going to be a problem for the next month and a half. Can a UPS can react to a power drop fast enough for it to not register on the electronics? Is there something I haven't thought of? Will the power fluctuations even hurt the expensive electronics? Are my only two options either A) sweat and watch TV or B) be cool and read a book to flickering lamp light? Thanks, Hivemind!

posted by Osrinith to technology (6 comments total)

I think what you want is a voltage regulator.
posted by Nothing at 2:31 PM on August 18 [2 favorites]

I live in an old building with a similar problem. We got a UPS but this didn't actually seem to help. In the end we got several voltage regulators as suggested above. This helped tremendously.
posted by ZeroDivides at 2:35 PM on August 18

Thanks, you two. I'll give the voltage regulators a try. Just for clarification, ZeroDivides, did you plug the AC unit into a regulator as well or just the other electronics?
posted by Osrinith at 3:12 PM on August 18

Voltage regulator is probably the place to start but, if you do go for a UPS, don't bother with anything other than a Falcon. Yes, they are more expensive (starting at about $1600) but, after going through countless crappy UPS units, I stepped up and have been thrilled with the difference. That I could have bought two Falcons for the amount I've spent on the charlatan versions over the last decade is something I prefer to not think about.
posted by bz at 4:11 PM on August 18

You plug the computer, or whatever it is you wish to protect from line variation, into the voltage regulator. Leave the AC unit as it is.
posted by bz at 4:12 PM on August 18

The AC draws a lot of power and gives you the brownouts. It also works. The electronics on the other hand need the steady voltage to work. In addition the voltage regulator linked to by Nothing is rated for 600 VA, so there is a limit on how much power it can supply. Maybe you need a bigger one even if you don't plug in the AC.
On preview bz says it much shorter.
posted by mmkhd at 4:22 PM on August 18