ac woes, again..read other one first

[mike avera]

sorry..i hit send before i was done...anyhow, it has been pretty hot lately....but it seems like the ac should be doing a better job than it is. and that bill was just too high. any ideas?

[Mort Guffman]

My only thought is to hire a qualified a/c guy to come out and diagnose the problem, then hope your landlord will pay to have it fixed.

Otherwise, you need to move out, or just live with it.

mort

[Edwin Pawlowski]

Couple of factors.

What is the outside temperature? With triple digits,getting down to 80 is about maximum. Most central units are designed to reduce the temperature about 20 degrees.

What was the bill last year? What was the average temperature. What was the kW used? More load = more cost.

The air coming out will vary at times. With a window unit, If the compressor is running, the air will be cooler, but once the thermostat is satisfied, the fan keeps going blowing air that is the same temperature as the rest of the room. Some packaged units run the same way. You don't give any information on the type of AC you have so I can't be more specific.

FWIW, my bill last month was $186. I was expecting over $200.

[CJT]

I think you're confusing the expected drop across the coil with the difference between indoor and outdoor temperatures. They're two totally different things.

Most central AC units are sized to allow keeping indoor temperatures and humidities comfortable over the range of expected outdoor conditions (or nearly so). If that means the unit must be able to lower the indoor temperature to 35 degrees less than the outdoor temperature, so be it.

You're not cooling outdoor air to room temperature. You're cooling air drawn from indoors to 20 or so degrees less than it already is, and mixing that with the other indoor air. Even if you start with indoor air at outdoor temperatures, you can incrementally lower it by more than the drop across the coil.

[mike avera]

the outside temp has been 90-92...as far as last years bill, this is my first summer here so no comparison. and i wouldnt mind paying the big billsif in fact i was comfortable. instead, its hot and sticky in here while the unit blows lukewarm air. i called and left message with the apt. maintenance last night so hopefully i'll hear something today. i keep it at 78..and the room temp hovers a shade above 80. should i lower the setting? its just odd..it'll run for 2 hours, shut off for about 10 minutes, then run another 2 hours..just doesnt seem right..

[m Ransley]

Sure lots of ideas, why don`t you educate yourself, start here www.energystar,gov

[Edwin Pawlowski]

No, I said what I meant, and I meant what I said.

You proved my point. "expected" outdoor conditions. If normal high is 90 degrees, and this year it gets to 105, the original design limits are still in place. That is a very large difference. This is all based on supposition since neither of us knows what the desgn was for (aside to be cheap for the apartment owner)

By oversizing to allow for the two days a year of extreme heat, you lose some humidity control when the differential is low for 80% of the cooling season while it may be OK for the other 19,5%

True, but when the "expected" outdoor conditions are exceeded by 10 or 15 degrees, there is a lot more heat gain than normal. I'ms ure you've seen the higher than normal temperatures across the country this summer. Other conditions may have ch anged also. Adjoining apartmnts may be empty and not cooled adding more heat gain, the huge shade trees on the sidewalk may have been taken down last winter.

[CJT]

Have you (or perhaps your landlord) signed up for a load shedding program with your utility?

[CJT]

There are parts of the world where 115 is "expected," and they still have comfort indoors. A 20 degree drop wouldn't allow that. I was trying to be gentle, thinking you had probably merely spoken imprecisely, but now I think you're just off base.

If normal high is 90

Global warming is real. Get used to it.