Ashton Crusher wrote:
On Wed, 08 Aug 2012 16:50:19 -0400, "
wrote:

On Wed, 8 Aug 2012 11:39:46 -0700 (PDT), "
wrote:

On Aug 8, 2:24 pm, "Ed Pawlowski" wrote:
"Hell Toupee" wrote in message

It's called a SaverSwitch by my utility company. They come out and add it
to the a/c unit, in exchange for giving the customer a 15% discount on
their monthly electric bill. The utility remotely controls it - during
peak load times (which are only an occasional thing hereabouts) they turn
off the a/c's compressor every twenty minutes or so, leaving the fan
running to circulate air in the house.

They claim that most people will typically notice little or no difference,
comfort-wise, when this is done. However, my sister has a 4-level home and
when she was on the program, her upper levels simply never had a chance to
cool down sufficiently, so she had them remove the switch.

I can see that system working, based on my own experience with AC. Short
down times are not a big deal. Many people keep the house cooler than it
has to be and a brief time down makes no discernable difference.

Recently, on a pretty hot day, there was a quick power outage. My AC went
off, came back on but not in the "cool" position. It took about an hour
before I finally noticed that it was getting overly warm. If the power
company has shut it down for five of twenty minutes, I never would have
noticed.

In the case of your sister's house, the system is either not sized properly,
not laid out properly, or not installed properly. The technology to have a
well balanced system has been around for decades. Unfortunately, things like
this happen.

I don;t know about that. An AC system is supposed to
be sized so that it runs most of the time on the hottest
days. If the power company then turns it off so it can't
run as much as it needs to, it seems perfectly possible
that some people could wind up with homes that are
too hot.

Another way of looking at it is this. The power companies
claim that it makes no difference in the temp in your
house. If that's the case, what good does it do the
power company? All the AC units out there are already
either randomly cycling because they can maintain the
set temp or else just running all the time. If they are
randomly cycling, then how do you reduce the load
to the power company without reducing the cooling?
If the ACs were all coming on and off at exactly the same
time, then by fooling with then, the power company
could even it out. But because they are already random,
I don't see what they are doing having any effect unless
it raises the temp in the house. And if the AC is running
100%, then for sure turning it off for 10 mins is going
to decrease the cooling output.

Absolutely right. The only way to save any energy is to decrease the average
delta-T (make it warmer in the house). Otherwise, you're just shifting *when*
the compressor is running, not how much. I don't see how shifting it by ten
minutes helps either. It'll just draw more power (than it otherwise would
have) later.

They are trying to reduce PEAK load. Lets say there are 1,000,000
power customers. And lets say they want to reduce the peak load 10%.
If all those users AC units were running then turning off 10% of the
running AC units would get MORE then a 10% reduction in peak load
because the AC while running is probably 50% of the load on each
house. So they only need to turn off perhaps 5% of the AC units at any
one time. If the meters are really "smart" they would be able to tell
if the AC is on or not if by no other way then simply the current draw
at that point in time compared to the average for a typical day in the
season. So they should be able to target running ac units. And since
it's "smart" they should be able to shut down *just the right number*
of them to reduce the peak load to whatever their target is. Going
back to it probably being 5% or less needing to be turned off at any
one time, that means of the 1 million houses, if they cycle thru each
house so no house gets hit twice until all the houses with running ac
have had a turn, it means they need to turn off 5% of a million, or
50,000 AC's. If they want to keep the off time to 10 minutes (1/6 of
an hour), it means that for every hour they want to reduce the peak
they need to deal with 300,000 AC's. Given that they have a million
of them, and on a really hot day most of them will be running at any
point in time, that means they have a 3+ hour time period where they
can be turning off AC units without ever hitting the same house twice.
Rounding up to make this example worse, lets say I'm off by a factor
of two, it still means that at most your AC will be turned off for 10
minutes twice in a 3 hour period and the off time would be 1.5 hours
apart. I doubt many people would ever notice those two-10 minute off
periods 1.5 hours apart. And for those rare people who do notice it,
by the time they notice it more then likely the 10 minutes will be
expired and it will be back on.

I just went thru this on the fly so I could have missed something but
assuming it's a reasonably good armchair estimate, the use of smart
meters to control peak use seems like a very good way to save money
(by not building excess capacity to deal with a couple hours of peak
use) with essentially zero impact on anyone's comfort and convenience.

While a quick read of this seems to make sense, the one statement I might
have an issue with is this:

"And since it's "smart" they should be able to shut down *just the right
number* of them to reduce the peak load to whatever their target is."

If you are talking about the meters, I don't think that they are smart
enough to know what's going on across the grid. Some other system would
have to tell the meters which AC units to shut down and for how long.

I think. ;-)