This is our second summer on the energy-saving program, where you allow the utility to remotely shut off your outside compressor for a few minutes each hour during times of high electrical demand.
It sounds like a great way to shed loading on the electrical grid, and stave off brownouts (or blackouts).
AEP installed a Digital Cycling Unit (DCU) that interrupts the operation of the compressor periodically, upon reception of a radio signal.
We can tell when the compressor is pre-empted by both a red LED, and unfortunately, a steep climb in room temperature.
The latter isnt supposed to happen, Im guesing, but some experimentation solved the mystery.
When the DCU is triggered, only the outside unit is turned off, and the inside air handler continues to circulate air as long as the thermostat is demanding it.
With a well-installed A/C system, that would just mean the air handler circulates the air without any cooling taking place, but in our system the ducts are roasting in our attic, and circulating unrefrigerated air through them just pumps attic heat into our living space. You dont notice that when the A/C is working properly because the cooled air overcomes the hot air picked up in the attic, but turn off just the compressor and the inefficiency is immediately apparent.
So in our case, the inside fan remaining on is actually worse than if the DCU had just shut the whole system off.
Apparently the DCU works by interrupting the low-voltage signal between the inside air handler and the compressor, but Im thinking of asking them to move it inside so that it interrupts the output of the transformer instead (thereby controlling both the inside and outside units).
It's something I could easily do myself, but I want to play fair and not be accused of tampering. The only downside to that is the thermostat would go blank while the DCU was doing its thing, but that would only be a few minutes at a time.
Anyone having a similar experience?
(http://media.cmgdigital.com/shared/lt/lt_cache/thumbnail/400/img/photos/2011/08/18/100_1475.JPG)
Sounds like a good excuse to wrap some insulation around those ducts! ;D
Quote from: nathanm on August 12, 2012, 09:06:24 PM
Sounds like a good excuse to wrap some insulation around those ducts! ;D
But, you have to wrap the right amount. I remember a text book exercise in Heat Transfer that shows that some insulation may be worse than no insulation. It has to do with heat conductivity, exposed area, and probably a few other things I have forgotten.
Quote from: nathanm on August 12, 2012, 09:06:24 PM
Sounds like a good excuse to wrap some insulation around those ducts! ;D
Of which many are sheet-rocked in and inaccessible.
I could add more vents in the roof and awning, but that may not be enough.
Got a voicemail saying PSO was pulling the plug on the program, and they would be removing everyone's equipment in the coming weeks.