Subject: From: Date:

Re: [ECS] Load Control Dan Dubay Wed, 15 Jul 1998 08:31:39 -0400

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Larry,

It is very interesting to hear the how much the methods of climate control
differ in the southwest from here.  I would love to see a system like yours
one day.  One of the most efficient methods of cooling used in Michigan is
geothermal.  Is it popular out your way.

A friend of mine installed a system recently.  I was fascinated to check it
out.  Quite an engineering accomplishment!  They are relatively expensive
but usu pay for themselves in about five years. They are most efficient at
cooling.

Thanks for the info!   Dan Dubay

>Dan,
>     What you are describing for your AC is what I have heard of as a "rolling
>load shed". Although not offered in this area, it is interesting that it is
>available from other utilities. If my understanding is correct at some pre-
>defined demand (the utility's total customer demand probably in megawatts)
>they would start the interruptable load shed. Depending on system design the
>on/off features can vary.
>     Obviously, depending on where you live and the type of utility services
>you have will define to some extent how you approach energy load control. I
>have an all electric home and live in the southwest. We have high summer
>temperatures with varying humidity. The humidity for a great majority of the
>time can be relatively low . This allows for the use evaporative cooling until
>the dew point which is a good indicator for both humidity and temperature
>reaches certain levels. The new high efficiency pads of "Celedek", and the
>newly designed air handlers and water delivery systems for evaporative coolers
>makes for a very good choice for certain geographical areas. In addition the
>low humidity allows for the use of air conditioning "pre-coolers". These are
>"Celedek" pads with controlled water delivery that pre-cools the air entering
>your AC condenser coils. This greatly improves the efficiency of your AC.
>     So, what all do I have here? I have seperate thermostats for the AC and a
>separate thermostat for the evaporative cooling. I can control which type of
>cooling is to be in use. You do not want both the evaporative cooling and the
>AC on at the same time since they share the same ducting! I have control of
>water delivery to both the evaporative cooler and the AC pre-cooler. A fan is
>available for forced air venting of the attic air space and a plenum
>humidifier is available for winter use.
>     Right now all of this can be controlled through a control panel located
>near the the thermostats. Using ECS logic, control systems, and indications I
>hope to make this more automated. For example: In the early part of summer or
>late spring when the evaporative cooler is most efficient ECS would select it
>for use. Whether water is applied to the pads or not depends on the ouside
>temperature. At night when the outside temperatures are lower use this air
>without any further cooling. Add water if the outside temperatures are say
>greater than 80 degrees. ECS would switch from evaporative cooling to AC if
>the dew point exceeds 40-50 degrees. Water will be applied to the AC precooler
>pad if outside temperatures exceed 80 degrees.
>     The use of an attic fan as a cost saving measure (obviously summer only)
>is a complex issue. It depends on your attic insulation and I would think, the
>temperature differential between the attic air and inside air temperatures.
>     For winter cost savings the use of an humidifier will allow you to run a
>few degrees cooler and still feel comfortable. ECS will control this device
>based on the inside humidity. Right now control is handled through a
>"humidstat" and manual control override.
>     As I mentioned, I am able to do this all through manual means now, but
>ECS will do a much better job. For example, ECS can measure the temperature of
>the air as it enters the pre-cooler pad and measure the temperature as it
>exits. It can do this continuously and if the two temperatures become the same
>or nearly the same will shut the water off. No way can I be that efficient.
>     Right now all cables are pulled, interposing relays are mounted, and a
>great majority of the wiring is completed. Some features are in and
>functioning. I just need to keep working toward a completion. My interest has
>increased since the basic system upgrades and my motivation now has vastly
>improved.
>
>Have a good day,
>
>Larry C.
>

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