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Ground Loop Heat Transfer Question - Page 4

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Posted by Robert Scott on September 8, 2006, 2:10 am

But first check the hardness of your well water.  If it is very hard, then your
heat exchanger will degrade with calcium deposits.  A closed loop is much kinder
to heat exchangers.  You don't want to be replacing the heat exchanger every
couple of years.

Robert Scott
Ypsilanti, Michigan

Posted by Alan C37 on September 8, 2006, 12:22 pm
  Good idea, Thank you.
  As I said my well tank and pump are in a concrete enclosure which is below
ground level with an insulated cover.  This is about 60 ft from the house.
The well hole was drilled down from the floor of the enclosure and was about
40 ft deep.  In the early 1990s we had a very dry summer and the well went
dry on me.  Drillers refused to attempt to drill it deeper for fear of metal
bits having been dropped down there (I don't blame them).  They did,
however, drill a new well a few feet outside the dry well enclosure (at a
cost of $400) and I linked the pipes back into the dry well and all has
been "well" ever since.  The new well reaches 85 ft deep and has a lot of
water in it.  The top of the water is usually about 30 ft down.  I don't
know what the maximum capacity is but I have used it for extensive garden
watering and sometimes filled an above ground swimming pool with no
troubles.  The point is, of course, that already I do have two well holes
which are, unfortunately, located within about 6 feet of each other so doing
what you suggest would be relatively easy and certainly deserves further
  I had not seriously considered doing this because the wells are so close
together and I am unsure what effect this might have on my drinking water.
  Our local rock is limestone and the water is quite hard but I assume I
could use a softener of some kind.
  I have done some further simple minded calculations on the original idea
and find I would need a lot of fairly large pipes simply to achieve the
surface area I would need to enable sufficient heat to flow between ground
and the water in the pipe, given the fairly small temperature difference I
would have.  I seem to need about 400 ft of 6 inch diameter pipe.  If this
is made of 0.1 inch copper the pipe would have a mass of nearly 3000 lb
which would be expensive to buy.  Maybe plastic would be OK although it
would have a higher thermal resistance This may well make it not worth the
initial cost.  Certainly your scheme requires only about 60 Imperial gallons
per hour which is well within the capability of the existing 1/3 hp pump
(300 gph if I remember correctly).
  Thank you all once again.  The quest for savings continues :-}
  Alan C

Posted via a free Usenet account from http://www.teranews.com

Posted by dold on September 8, 2006, 4:28 pm
 It might very well be illegal.

Wells are required to be sealed to 30 feet below the surface around here.
The people that I talked to about this said that it had been considered,
and was thought to be a very bad idea.

What comes out of the ground and passed through anything should not be
returned to the groundwater supply.

Clarence A Dold - Hidden Valley Lake, CA, USA  GPS: 38.8,-122.5

Posted by Robert Scott on September 8, 2006, 8:24 pm

At the flow rates you are talking about you will go broke trying to soften that
much water.

Robert Scott
Ypsilanti, Michigan

Posted by daestrom on September 8, 2006, 8:44 pm

I'm not so sure softening is required.

Calcium deposits are usually a problem when you *heat* the water.  As the
water is heated, the various compounds come out of solution and form all
sorts of hard scale.  That is why hot-water heaters and hot water piping
have scale build-up in hard-water areas.

But he's *cooling* the water.  Scale may never build up in that sort of
application, so softening wouldn't be necessary.


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