Subject: From: Date:

RE: [ECS] Need quick HVAC advice Steven Wegman Wed, 16 Jun 1999 22:36:54 -0400

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At 09:52 AM 6/16/99 -0400, you wrote:
There's a Maryland installer at
>www.groundloop.com who can give you some good information. I'm pretty sure
>he covers Northern Virginny, as well. He installs two different brands of
>units and can give you the advantages/disadvantages of each. One unit is
>capable of generating all your hot water as well as heating/cooling. Check
>out the links on his page and/or give him a call. He was really friendly.


	My units are made by American Standard.  Don Lowe and Sons, in Damascus,
MD.  did the install.  It is a family operation and they were very good and
knowledgable.  I dealt with Don Lowe, Jr.   They designed a quiet system
with over-size ducts.  In fact, the duct noise is so low that when I later
designed a home theater room, I was told that the HVAC system would NOT
need to be revised to prevent noise intrusion into the room.  Also, a fiend
of mine, who designs such systems for schools, the "new"  DC convention
being built, etc., told me that Don Lowe's install was not a residential
quality install, but rather, a commercial quality install.

	There are two basic types of geothermal systems; open loop and closed loop.

	In a closed loop system, pipes (200 to 400 feet in length) are placed
under the ground and an anti-freeze type liquid circulates in the tubes.
The ground is constantly approx. 50-55 degrees.

	In an open loop system, you drill a supply well and a return well.  The
two wells are spaced apart from each other, so that a temperature
differential in one does not affect the other.  You extract water from the
supply well to heat or cool the house.  Thereafter, the water is returned
into the ground via the return well.

	Both systems can use excess heat to provide hot water.

	An open loop system generally has a higher effeciency than a closed loop
system.  The drawback of the open loop system is that you need to draw a
minimum of 1 and 1/2 (preferably 2) gallons per minute for each ton of the
heating and cooling equipment.  In my house, that means drawing
approximately 22 gallons/minute when all 3 HVAC units operate.
Fortunately, they are so efficient that all 3 units are never on at the
same time.

	BTW, with an open loop system, you can provide cooling without the use of
the HVAC compressor.  Instead. the water extracted from the supply well is
passed through a heat exchanger located over the A-frame.  The blower fan
extracts the cool temperature in the water to cool the house without
running the compressor.  For example, in my house, the compressor ran a
total of less than 2 hours for the entire cooling season (e.g., May through
September).  This also has the benefit of increasing the EER rating (that
is why my unit is rated at 30+ EER).  As a result, my electric bill is less
in the summer, as compared to the winter (when the compressor must run to
heat the house).  This has the benefit of keeping off of time-of-use
metering with the electric company (PEPCO).  With PEPCO, if you use more
than 2500 KW/month for two consecutive cooling months, they place you on
time-of-use metering.  I have not come close to this my house.  On the
other hand, I have a friend on this system, and he tells me that peak uasge
rates are approx. 2-3 times higher (with the cheapest rates being between 2
am and 6 am).

steve wegman
swegman@erols.com

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