[Trash Can]

Originally Posted by TomKBL

His point is set it and leave it; mine is turn it off or set it higher when not home. I have no issue with properly sized unit. with properly sized unit if you turn it off or set it higher when not home, you save more.

Originally Posted by von949

Not if you turn your system off and come home to a 100+ degree home. How long and how much power will be needed to bring your home temperature to a comfortable level?

I don't think the answer is clear cut. The best answer probably is "it depends." MBA summed it up pretty well below.

Originally Posted by MediocreButArrogant

If you return to the house late at night, when it has cooled off outside, you might save money by letting the house get warm while you are gone. The A/C will be doing all of its hard work when it is operating more efficiently due to the cooler temperatures outside. If you return at the hottest part of the day, you'll probably spend more by letting the house get hot while you are gone, because you'll be trying to cool it when the A/C is operating least efficiently.

[TomKBL]

Originally Posted by Trash Can

I don't think the answer is clear cut. The best answer probably is "it depends." MBA summed it up pretty well below.

The following may be helpful.

Turning off the air conditioner.

[tiger08]

Ok here is whats going on.

My previous 4 ton unit used to pull 19 amps on each leg, this was checked at my circuit panel and this was on a hot day, the unit also cycled off and on quite frequently.

The new 3 ton unit pulls 12 amps on each leg on a hot day. The unit runs almost constantly at any temp over 103 outside.

So we have a difference of 7 amps per leg between the two units, now times that by two, thats 14 amps. A 14 amp difference is quite a savings in itself, plus the longer run times of not restarting several times per hour.
I also added a DC powered blower motor, so a slight savings there, plus a start assist kit for easier compressor startup. Not to be confused with a kick start, or hard start kit, they can be bad for compressors.

My neighbors who are running 5 ton units, are pulling up in the 23+ amp range, each leg and their units dont run long enough to dehumidify on a wet day, their houses are very uncomfortable. They also have very high power bills and dont run their stat anywhere as low as I do.

My main goal originally was not so much for the savings but for the comfort. I find a house to be very uncomfortable when the unit switches off. If someone was to sit in a house with the air set at 77 degrees and the unit was cycling off and on, the house would not be comfortable, not to me anyways.
Now take the same house at 77 with a constant running unit and it is quite comfortable.
I never intended for my new smaller unit to run at 71 degrees, I didnt really think it would be capable of even maintaining that low of a temp but so far it hasn't crept up yet.

[tiger08]

( quote TomKBL)

BTW, most ac techs are good at fixing ACs but no need for them to really unsderstand what's really going on.[/quote]

I totally dissagree. Why shouldnt an a/c tech learn every aspect of the hvac field? Thats the problem we have in this valley, among many other places. Most techs I discussed my project to said a 3 ton unit would not cool our large house.
They all scream 400 square feet per ton and any tech who truly believes that rule, might as well retire or find a new trade.

[Darthfrodo]

77 during the day, 74 at night.

[TomKBL]

Originally Posted by tiger08

The new 3 ton unit pulls 12 amps on each leg on a hot day. The unit runs almost constantly at any temp over 103 outside.

Tiger, if your unit runs almost constantly, either you set the stat temp too low or the unit is simply not able to handle the house.

Think about it, each A/C unit has a life, 10 or 15 yrs. But more precisely the life should be measured by hours of running, just like the life of a light bulb measured by hrs. Just my 2 cents.

[MadManofBethesda]

Originally Posted by Trash Can

I don't think the answer is clear cut. The best answer probably is "it depends."

Absolutely. If you look at the issue logically, there has to be a point where it is cheaper to turn the a/c off or thermostat up rather than the alternative set it and forget it argument. If you're going to be away from the house for a week, it is obviously cheaper to turn the thermostat up or the a/c off for the week and then reset it upon your return rather than have it run continuously while you're away. If you're only going to be gone for an hour one afternoon, that won't be the case and it could cost you more to turn your a/c off and on for that period of time.

So logically there has to be a point of time, somewhere between one hour and one week, where the costs balance out and then from that point on you're better off turning your thermostat up or your a/c off in your absence. The question is, when is that point reached? Of course, that answer also could be the same "it depends."

[tiger08]

Originally Posted by TomKBL

Tiger, if your unit runs almost constantly, either you set the stat temp too low or the unit is simply not able to handle the house.

Think about it, each A/C unit has a life, 10 or 15 yrs. But more precisely the life should be measured by hours of running, just like the life of a light bulb measured by hrs. Just my 2 cents.

You didnt read my whole post, the unit keeps my house at a constant 71, I want the unit to run more.

A/c units that dont shut off and on constantly, last much longer.

I've already mentioned in past posts that a/c compressors dont like frequent cycling, it wears them out much quicker, along with capacitors and contactors.. My long run times will greatly extend the life of my unit and its related parts.

An air conditioner that cycles too frequently is not achieving anywhere near its seer rating, you need long run times to achieve full efficiency.

[Bps401]

Originally Posted by Raiderman

We just switched to TOU this past Friday. I work from home from 6a-2p, and the TOU rate jump is 1p-7p. We have it programmed to:

6a-10a - 76
10a-1p - 74
1p-7p - 85
7p-6a - 76

I like to go on the NV Energy site and look at the flat line between 1p and 7p.. makes me FEEL like I'm saving money, anyway LOL

Flat line? Where can i find that on the nv energy site?

[Raiderman]

Originally Posted by Bps401

Flat line? Where can i find that on the nv energy site?

Log into your account, and on the top right it says "Smart Meter Usage". Click the "Show My Energy Use" arrow below that. On the graph dropdown, select 15-minute energy usage. It will look something like this if you shut down the house between 1p and 7p (which we do anyway, YMMV). Notice between 1p and 7p it's virtually 0 when the rates jump to $.33/kwh