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Ground Loop Heat Transfer Question - Page 3

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Posted by daestrom on December 16, 2006, 3:59 pm

Not in a freezer :-).  It's like lining the interior with foamboard.  It
takes a lot longer for any heat in the food placed in the freezer to migrate
through the insulation to the cooling coils.  Of course, once it's frozen
the only heat that needs to be removed comes from opening the door or
leakage around the door seal.  But if that heat leakages is faster than the
rate of removal through all the frost built up on the coils, then interior
temperatures will rise.

But as Jack pointed out, an igloo of snow can be rather comfortable even
when it's many degrees below zero.  Simple body heat will not leak through
the snow walls very fast and the interior warms up to the melting point.  On
winter campouts in my youth, we used snow and straw bedding to make a very
comfortable shelter.

In northern Michigan, a few years back, the town where my parents lived had
problems with frozen water mains on several streets.  The mains were only
buried six feet down (~2m).  That winter there was almost no snowfall and
the bare ground froze down deeper than it had in a good many years.
Normally, several feet of snow covering the ground prevents it from freezing
any deeper than about 3 ft (1m).


Posted by Solar Flare on December 17, 2006, 11:31 pm
Also to be added to your usual text rant is that it gets really dark
at night sometimes.

Posted by Alan C37 on September 4, 2006, 2:01 pm
   Thanks to everyone who replied.  There is a lot of excellent advice which
I will proceed to mull over at length.
  Calculating fluid flow rates is simple enough, even for me, given
knowledge of actual temperatures under known conditions but knowing in
advance exactly (or even nearly) what those temperatures will be is clearly
extremely difficult.  I have found data about ground temperatures at much
greater depths than I can reach but next to nothing about the first 10 feet
or so.  The 55 deg F figure is little more than a guess really.  The
temperature of the water coming from my well today is 54 deg F and this has
been sitting overnight in an uninsulated tank in an uninsulated concrete
walled dry well space about 4 feet below ground level.  Outside air
temperature is about 67 deg F.  There are several inches of insulation
covering the dry well space top.
  I am beginning to think that the only way is to actually run a smallish
test loop for a winter before deciding if the idea is practical.  This
should be easy enough to do on my site near Ottawa as I have about three
quarters of an acre of mostly deep sandy soil.  I could get a decent trench
dug for about $000 (C) and the pipe would be only a few hundred.  If it
doesn't prove worthwhile I can always use the pipe as a way of improving the
drainage of the ground around the basement, which I need anyway.
  The idea of using solar heat as the main source and storing heat in water
is one I have considered but put on hold because of the cost of the large
(600 ft^2) solar collector and the support structure.  They are ugly things
imho anyway and the local council might be difficult about planning
permission.  Non-the-less it might be a good idea if I combine it with a
garage and/or greenhouse.  Previous calculations suggested that this would
cost me over $0000 even if I did the work myself.  A bit rich for me and I
am probably too old to take it on now.
  My original post suggested 12000 Btu/hr because I can get such a heat pump
for less than $000, which is, I think, excellent.  Installation is simple
but I would probably need at least two of them, perhaps dual zone systems,
since I have no air ducts and these (ducts) are likely to cost way more than
I can afford.  I accept that I will have to use the baseboard heaters on the
coldest night but obviously want to minimise this.  I have about 20 kW of
baseboard heaters in this 1900 f^2 house but they don't all come on
together, I hope.
  I anticipate that the air enclosure around the heat pump outside unit
would be fully opened to real air for much of the Spring and Fall seasons
and the ground loop would be shut down.  This should allow plenty of
recovery time for the actual soil temperatures between the main heating and
cooling periods.
  My electricity usage over the last many years has averaged out at
3.5 kW continuously for everything.  This is now over $000 per year and I
don't like it at all.   I believe that the new heat pump(s) installed in the
conventional manner would reduce my energy costs to about $000 and the idea
of boosting the performance with a ground loop, if feasible might knock off
another $000.  If I convince myself that this can be done I will certainly
do it.  Payback time should be good enough.
  Once again, many thanks to all of you.  I will keep you informed of
progress, if any :-}
  Alan C

----- Original Message -----
Newsgroups: alt.solar.thermal
Sent: Sunday, September 03, 2006 11:58 AM
Subject: Re: Ground Loop Heat Transfer Question

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

Posted by Jeff on September 7, 2006, 7:37 pm
 Alan C37 wrote:

  Why not use your well as your source, that's assuming that you have
enough flow and you can run a return line down the well.

1) pump the water up.
2) run it through your heat exchanger
3) let the water return to the well, the weight of the falling water
should balance the weight of the rising and minimize the power needed.
You'll still need to overcome the initial head.

   Question that need to be asked:

1) What is the "turnover" in the well.
2) How to minimize the return flow from the inlet flow.

   Two wells (a source and a return) would work, if there is enough
water volume.


  and this has

Posted by Solar Flare on September 8, 2006, 12:33 am
 Grundfos circulating pump model UP25-64SU

153 watts with water flowing up 12' and siphoning down 10 = head diff
157 watts with water stopped by plugging end of pipe.
154 watts with pump in full cavitation.

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