Salvaging an improper geothermal install

[Astro]

see comments interspersed:

So you came up with less than 48,000 Btu/hr but did not include
infiltration? Infiltration could be 40% to 50% of the heating load.

Actually, I came up with something shy of 35kBTU/hr not including
infiltration. As you note, there could be a big slop factor in there. I
wouldn't be surprised if the true load at a design temperature of 5F was
60kBTU/h. I actually wanted a slightly undersized system, designed more
for around 15F so that I'd get the reduced consumption of a smaller
compressor for the majority of the run-time. However, I wasn't planning on
the BTU output dropping to ~50% of the rated output after a day or two of
use!

The sensors are down the bore holes? You know what the temperature is
50 or 100 feet down?

I had them put the sensors 50ft down the holes along with the loops so
that I'm getting a good feeling for ground temperature change due to the
loops, not seasonal surface temperature variations.

18F rise sounds like a heat source near or slightly below the freezing
point of water. What is the suction pressure now? What was the suction
pressure when you were getting the 23 degree rise?

You're good! the 18F rise is achieved when the loop field is right around
freezing.

I don't know the pressures. Was thinking of getting a set of gauges so
that I could measure them, but I don't want to screw with the system
without supervision of someone who is qualified.

It does sound like you are shy on the pipe in the ground, however, I am
wondering what assumed earth temperature is the design of these systems
based on. Just going back to my closed lopp indirect systems where you
based it on 30 or 32F temperature source from which to extract heat.

The manufacturer wouldn't provide me with the output curve. However, based
on their literature and what I gather from emails from their tech people,
the 4-ton rating is for ~50F ground temp. This matches well with my
experience - on the first day of operation, there was a 30F rise, and that
was when the ground was 51F.

Does the temperature keep dropping more and more? Is the temperature
source 'bottoming out'?

I've let it drop to ~30F. At that point, the output is so low (<15F temp
rise) that I turn it off for a day and run off oil until the ground
temperature recovers so I'm not blowing "cold" air. I'll try a long term
test to see if there what the point is at which the temperatures bottom
out.

Would it work on a reduced output after a while with a relatively
constant 18F output?. Maybe put in a hot water heating coil for your
back up, to provide the extra 10,000 Btu/hr you seem to need.

Is the return air ducted to the air handler or is it a central return.
Is return air up in an attic? The return ducts not sealed drawing in
some cold air?

Central return straight(goes thorough a 90 at the ceiling) into the
horizontal handler in the attic.

I've gone up and checked for input and output leaks and taped things up
carefully with metal tape. Probably should go around with mastic and seal
things up good. But at least for these measurements, I'm pretty sure that
I'm losing a minimal amount to return leaks.

All of my systems had lots of wet soil, and were selected based on a
temperature source near the freezing point of water. It is unfortunate
that you cannot take a advantage of the latent heat of water.

Actually, I think you still do with the DX to some extent. Since the wet
sand still has to go through the phase change, there's definitely a
flattening of the curve where you draw for a while at freezing then drops
below. Likewise, it takes 6 hours to phase change back to water but only
an hour per degree after that.
Or am I misinterpreting your comment?

It gets down to a COP of one? All the heat you are getting out of it is
equal to the electrical energy consumed to run it?

Not to my knowledge. But when the temperature rise drops down below 15
(i.e. output air < ~84F) the subjective comfort factor of the forced air
system is such that I switch over to oil.

Thanks again for your thoughts. It really sounds like you design your
systems realistically, whereas my company specs them out for best case
scenarios. Don't they realize that specing the system out like that will
just leave people dissatisfied? I would gladly have installed a 5 or 6 ton
system if I had known that the true operational temperature would be more
like 30F at which point the output would be 4 tons! I guess they just want
the initial sale and don't care about long term customer satisfaction.
That's certainly not how I ran my business.

 

[Astro]

This may be to optimize size and materials for an all-metal heat
exchanger.
The heat flow per square foot in this case is VASTLY lower due to there
being
negligible fluid flow on the outside of the pipe. So, I think the
thermal diffusion
becomes significant when the turbulent flow is not dominant. Anyway,
the owner
of this disaster probably wants to avoid pulling up the loops that are
already in.
And, running several thousand feet of large-diameter pipe horizontally
is going to
get darn expensive, too. Probably running parallel loops of smaller
pipe spread out
in the field will end up performing better than one big pipe.

Jon

I'm evaluating a variety of option. Since the existing loops are only
backfilled in sand, it *might* be feasible to flood the holes and pump out
the sand/water slurry, then drop the additional loops down the holes to
create a (inefficient?) heat exchanger. However, doing so brings with it
some flexibility. During the Winter, one could pump transfer fluid from
horizontal loops to bring energy back into the vertical loops. During the
Summer, when the vertical loops are getting hot, one could bleed the heat
through a seperate heat exchanger and heat the pool or DHW

The horizontal loop field might not be too expensive compared with options
like adding more vertical bores. Around here, drilling runs $6+/foot. To
bring the system up to spec might require another 750 ft. of bores. So
drilling alone could cost another $5k. I'm not sure what the manufacturer
would charge to add more vertical loops to the system. And, given that I
proposed this and they didn't reply, I'm looking at a worst case of having
an orphaned system that I may have to kluge to improve the performance.

On the other hand, I've got an excavation contractor friend who could do
the horizontal trenching for a fraction of this. But by the time you add
several thousand feet of PEX, manifolds, pumps, etc., we're back up to
five grand. But I'd consider that a reasonable investment if it resulted
in a system that satisfied my heating needs.

Interesting note about multiple small loops rather than fewer larger
diameter loops. Jon, are you thinking about thermal transfer benefits
because of thinner walls, greater tube surface area as well as more
thermal mass covered?

 

[Astro]

On Fri, 21 Jan 2005 22:08:31 GMT, daestrom

Well, I don't have any direct experience with GSHP's, but I'm doing a
little
'noodling' around with numbers on a spreadsheet here and this is what
I've
figured out so far.

If you treat a bore hole as 1 ft diameter and 100 ft long cylinder
surrounded by granite, the calculations of temperature gradient across
the
granite are pretty straightforward if you assume the steady state and the
surrounding granite is uniform temperature. One could add on the lower
hemispherical region as well, but maybe later. Looking around on the
'net,
I found a few numbers for granite, ranging from 2.3 to 3.9 W/m-K.
Assuming
2.5 W/m-K as sort of towards the worse end of the spectrum, that's 1.44
BTU/hr-ft-R (if I got my units right ;-).

With To - Ti = q/(2*pi*k*l) * ln(Ro/Ri) for a cylinder, and assuming you
try
and pump 1 ton of heat out, then in the steady-state you would have a
temperature gradient in the first foot moving outward from the bore of
app...

To - Ti = 12000/ (2*pi*1.44*100) * ln(1.5/.5) = 14.5 R. Moving out to
distance 3 feet from the bore center, it would seem to be =
12000/(2*pi*1.44*100) * ln(3/.5) = 23.7 R. Frankly, these seem like
pretty
strong gradients for natural rock, but what the heck.

Applying some calculus we can find the theoretical temperature gradient
at
any distance. The gradient drops to less than one degree/ft only when
the
radius gets out to about 13 foot radius. At that radius, the central
bore
is 44 F cooler than granite at 13 ft. If the ground temperature is only
~45
F to begin with, this means the central bore would *have* to be around 1
F
to sustain a long term heat output of 12000 BTU/hr. Mind you, this is
just out to the 1F/ft radius, that probably isn't the true radius of
influence of this bore, I just chose 1R/ft as a guess.

So with multiple bores as close as 6 ft, it is clear that their 'radius
of
influence' overlap. And that's bad. The temperature gradient to get
12000
BTU/hr must be even steeper on the sides away from neighboring bore
holes to
make up for the interference caused by the neighboring bore hole cooling
the
granite on the sides between neighbors

Of course you don't need to run continuous (at least most HVAC systems
are
designed not to require that), but on really cold days (like this on in
NY
where we broke some records at -11 F), you might need/want this much
capacity.

The hemispherical zone at the bottom would help this a bit by allowing
conduction from directly below the end of the bore. But there are other
factors that make further refinements kind of moot. Things like the
temperature gradient going down the bore is probably not uniform, and the
area near the surface is influenced by the surface temperature.

Water in soil will generally improve the situation since water's thermal
conductivity is higher than diamotaceous earth (~0.4 BTU/hr-ft-R vs ~0.04
BTU/hr-ft-R). But it needs to permeate the entire soil around the bore
whole. And that's something you don't have (IIRC you indicated these
bore
holes were in solid granite).

Frankly, using these calcs for normal soil seems to show that 1ton/100
ft is
not a practical number there either. Either my calcs are off because I
missed something, or 100ft / ton is wildly optimistic. And the 'radius
of
influence' would seem even larger for poor thermal conductivity soils.
Or
they conventionally rely on *moving* ground water to increase the heat
available by convection.

One thing I'm not clear on, is if the liquid refrigerant enters the bore
hole through an pipe and descends to the bottom, then vaporises as it
rises
up a second pipe, it would seem some of the heat gained in the deep part
of
the bore is lost as the refrigerant passes out the last 10-15 ft near the
surface. That is to say, the flowing refrigerant is warming some of the
frozen rock near the surface with deep well heat, instead of coming into
your home. Or do they insulate one pipe to avoid this?

Thoughts??

daestrom

That's the kind of calculations I've been toying with, though I hadn't
figured out the calculus yet. But as you noted, it didn't look overly
complicated for a first order appoximation.

Let's assume that the math is correct and you've got that type of
gradient, what about the diffusivity and the recovery of the center
cylinder? I've not been able to tackle that one. For example, if you pump
1 ton for 12 hours, how long will it take for the temperature to recover?
Likewise, if you run long term at X% duty cycle, what will the steady
state loop temperature be?

I asked the manufacturer for these types of analysis so that they could
prove that the system would work under my conditions with 100ft/ton, but
they never responded to that question (this was post-install). I'm
thinking that some simulations of the sort you've done can show that
100ft/ton cannot work under virtually any real life conditions. If this is
so, then they're guilty of fraud. My guess is that they're used to working
in active ground-water situations and are overly optimistic in their heat
transfer estimates.

Relating back to my initial question of retrofitting, if the thermal
gradient is indeed that steep, then the deltaT may be much greater than I
estimated. As such, it may be that supplying energy via an auxililary
ground loop run into the existing bores might work well.

As to your last question - you guessed it - they insulate the return tube.
Not much, just a layer of plastic around it. if memory serves me right, it
was ~1mm thick.

 

[Astro]

Just a long winded response, I guess I am saying you need to look at
what everything in the system is doing before you make 'repairs'. It
could most likely be not enough pipe in the ground, but you need to
verify everything else first, so you know exactly what you are up
against.

If this goes to court, you will need complete measurements of all
parameters.

Your suggestions make a lot of sense. These are the types of measurements
I would like to complete to further quantify the system performance and
theoretical ground loop capacities. I'm looking to find a competent
geothermal engineer in my area (eastern PA)who might be able to walk
through all this.

Thanks again. you've been very kind to take the time to help.

 

[Nick Hull]

Interesting note about multiple small loops rather than fewer larger
diameter loops. Jon, are you thinking about thermal transfer benefits
because of thinner walls, greater tube surface area as well as more
thermal mass covered?

With multiple smaller loops you can run some today and others tomorrow
while today's restabilize their temperature.

 

[News]

Free men own guns, slaves don't

I'm a free man and have never fired a gun.

 

[pjm@see_my_sig_for_address.com]

I'm a free man and have never fired a gun.

Freedom comes not from you as an individual ( or me, or anyone
), but from society in aggregate.



Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's http://pmilligan.net/pmtherm/

 

[News]

daestrom,

You installed a shower grey water heat recovery unit a few years ago in your
hosue. How is it performing? Any figures available?

thanks.

 

[daestrom]

daestrom,

You installed a shower grey water heat recovery unit a few years ago in
your
hosue. How is it performing? Any figures available?

Well, since you brought it up, I went back and looked and I hadn't run my
'standardized measurements' for a while. So this morning I went and did
just that to see how things have been going. You may recall (or perhaps
not), that I installed it in May of 2002. Right away, the measurements were
showing a pretty nice temperature rise on the feed-water through the unit.
I was getting a nice 30 F rise when I ran my 'standardized measurement'
(when I hook up the thermometers and such, I run the same experiment to help
avoid variations from other influences).

In the spring of 2003, the performance had dropped somewhat, I was only
getting about 17 F rise. Then this morning, the measurements show a
respectable 31F rise again.

So it seems to vary somewhat. Probably some experimental error as well as
intermittent fouling of the waste line side. I have been able to reduce the
hot-water heater setting without anyone in the family complaining of running
out of hotwater when showering (my adult son is a bit of a 'hollywood'
shower user and even he hasn't complained . With a 'guesstimate' of the
number and length of showers in my household and the price/performance of my
gas HW heater, I estimate that this thing is saving me between $35 and $42
/year. Not as good as I had hoped, but will still beat a 10-year pay-back.
And with the price of NG going up things should improve from an economic
viewpoint.

I have the model for the larger waste-line, so it actually has two coils
around the waste line. The coils are in parallel on the potable side so the
waste water from the upper coil, that is already cooled some is what
feeds/heats the lower coil. Obviously this isn't the most ideal situation,
but that's what I have. I think if I build another house, I'll probably see
if I can use a smaller unit just for the shower drains. But that may be
tricky given that the unit must be mounted vertically.

Details::

The 'standard test' is to run only the hot water directly from the kitchen
sink to the drain while no other water is used in the house. Flow is
measured with a 3 gal bucket and stopwatch. Temperatures on the coldwater
in, warmed water out, and drain inlet are recorded. Flow is allowed until
all temperatures stabilize (yes, the hot water heater has to start up during
this, but the drain inlet temp doesn't vary much at all).

Date, flow (gpm), cold-feed (F), hx-outlet (F), dT (F), Waste Inlet (F)
5/19/2002, 1.374, 55.4, 86, 30.6, 123.8
12/15/2002, 1.295, 46.4, 84.2, 37.8, 131.
3/9/2003, 1.295, 50.0, 66.2 16.2, 133.7
1/23/2005, 1.374, 44.5, 76.2, 31.7, 107.6

The waste inlet has varied a bit since I adjusted the thermostat on the HW
heater a couple of times. I generally turn it down in the summer, and up in
the winter months. And of course, the cold-feed temperature varies with the
ground temperature outdoors since I'm on city water system

daestrom

 

[geoman]

Well, since you brought it up, I went back and looked and I hadn't run my
'standardized measurements' for a while. So this morning I went and did
just that to see how things have been going. You may recall (or perhaps
not), that I installed it in May of 2002. Right away, the measurements
were showing a pretty nice temperature rise on the feed-water through the
unit. I was getting a nice 30 F rise when I ran my 'standardized
measurement' (when I hook up the thermometers and such, I run the same
experiment to help avoid variations from other influences).

In the spring of 2003, the performance had dropped somewhat, I was only
getting about 17 F rise. Then this morning, the measurements show a
respectable 31F rise again.

So it seems to vary somewhat. Probably some experimental error as well as
intermittent fouling of the waste line side. I have been able to reduce
the hot-water heater setting without anyone in the family complaining of
running out of hotwater when showering (my adult son is a bit of a
'hollywood' shower user and even he hasn't complained . With a
'guesstimate' of the number and length of showers in my household and the
price/performance of my gas HW heater, I estimate that this thing is
saving me between $35 and $42 /year. Not as good as I had hoped, but will
still beat a 10-year pay-back. And with the price of NG going up things
should improve from an economic viewpoint.

I have the model for the larger waste-line, so it actually has two coils
around the waste line. The coils are in parallel on the potable side so
the waste water from the upper coil, that is already cooled some is what
feeds/heats the lower coil. Obviously this isn't the most ideal
situation, but that's what I have. I think if I build another house, I'll
probably see if I can use a smaller unit just for the shower drains. But
that may be tricky given that the unit must be mounted vertically.

Details::

The 'standard test' is to run only the hot water directly from the kitchen
sink to the drain while no other water is used in the house. Flow is
measured with a 3 gal bucket and stopwatch. Temperatures on the coldwater
in, warmed water out, and drain inlet are recorded. Flow is allowed until
all temperatures stabilize (yes, the hot water heater has to start up
during this, but the drain inlet temp doesn't vary much at all).

Date, flow (gpm), cold-feed (F), hx-outlet (F), dT (F), Waste Inlet (F)
5/19/2002, 1.374, 55.4, 86, 30.6, 123.8
12/15/2002, 1.295, 46.4, 84.2, 37.8, 131.
3/9/2003, 1.295, 50.0, 66.2 16.2, 133.7
1/23/2005, 1.374, 44.5, 76.2, 31.7, 107.6

The waste inlet has varied a bit since I adjusted the thermostat on the HW
heater a couple of times. I generally turn it down in the summer, and up
in the winter months. And of course, the cold-feed temperature varies
with the ground temperature outdoors since I'm on city water system

daestrom

Now this is an interesting off shoot of discussion! I have been looking for
years for someone who has done this. Can you indulge me further on your
system and if you have some pictures or links? You may wish to start a new
thread on this subject, its up to you guys.

Thanks

Rich

 

[daestrom]

Now this is an interesting off shoot of discussion! I have been looking
for years for someone who has done this. Can you indulge me further on
your system and if you have some pictures or links? You may wish to start
a new thread on this subject, its up to you guys.

I posted about it back when I first installed it. Google for 'gfx heat
exchanger'.

http://www.renewableenergyworks.com/products/gfx/gfx.html
http://www.eere.energy.gov/femp/pdfs/techfocus_gravity_film_ex.pdf

They work rather well and aren't too expensive. I suppose if you're handy
with a torch you could make your own too. Because it has no storage, it
only works for some types of water usage such as showers, or other
'continuous' flow uses. Doesn't do much at all for 'batch' mode such as a
dishwasher or laundry. Others have posted DIY schemes to do such things,
but this system just fits in the vertical waste line and doesn't impede
outflow or collect 'sludge'.

daestrom

 

[News]

Well, since you brought it up, I went
back and looked and I hadn't run my
'standardized measurements' for a while.

daestrom,

Thanks, terrific. On the gfx web site they claim commercial units which
have large volumes of waste water, have very quick paybacks and substantial
energy bill savings.

 

[Jon Elson]

Interesting note about multiple small loops rather than fewer larger
diameter loops. Jon, are you thinking about thermal transfer benefits
because of thinner walls, greater tube surface area as well as more
thermal mass covered?

It is the heat flow through the surrounding soil. A bunch of pipes
close together don't do much
better than one pipe, because the problem is not the heat flow from the
pipe to the immediately
surrounding soil, but the heat flow out many feet from each pipe. More
pipes close together
will seem to work better for a few hours, but eventually the surrounding
soil heats up/cools down,
and the heat flow goes to pot. With pipes spaced widely apart, they
don't interfere with each other.

I'm evaluating a variety of option. Since the existing loops are
only backfilled in sand, it *might* be feasible to flood the holes
and pump out the sand/water slurry, then drop the additional loops
down the holes to create a (inefficient?) heat exchanger. However,
doing so brings with it some flexibility. During the Winter, one
could pump transfer fluid from horizontal loops to bring energy
back into the vertical loops. During the Summer, when the vertical
loops are getting hot, one could bleed the heat
through a seperate heat exchanger and heat the pool or DHW


I didn't understand what you are saying here, but if you mean to add
more pipe to the existing bores,
I think it will have absolutely NO effect! The problem isn't transfer
from the pipes to the granite,
it is THROUGH the many feet of granite. More, widely spaced bores, or a
sub-surface horizontal field
is the only way to fix it. Since you already know the deep structure is
the WORST condition for a
GSHP, and the cost to drill is astronomical, I think the horizontal
field, or possibly some use of
the existing water well, is your only cost-effective option.

Jon

 

[Sylvan Butler]

I'm a free man and have never fired a gun.

You pay others to do so on your behalf. Police, army, etc.

At least have the courage and moral decency to admit it.

sdb

 

[Nick Hull]

Only because others have done so and are willing to do so in your
place.

A really good comeback, do you mind if I steal it?

 

[William P.N. Smith]

One other option would be a small boiler to heat the loop water

You're better off putting that heat directly into the house than
trying to warm up the ground with it...

 

[Jon Elson]

Hi Jon,

To clarify the second pont - I was proposing adding additional loops
to the bores. However, those loops wouldn't go to the GSHP, as you
said, energy transfer from the bore is not the problem. What I was
proposing is to circulate water from another ground loop (or from a
standing column well) through these loops. as such, the effect is to
transfer energy from another loop field with much greater thermal
capacity so as to augment the recovery of the original loop field.

Does that make more sense?

Oh, wow! That is a VERY interesting idea! Of course, this it how to make a
$10,000 water-DX heat exchanger, which probably is what should have been
done
in the first place. A water loop would have a number of advantages to
the DX
system with very limited thermal field that you now have. If you were
going to
break the refrigerant system anyway to do this, you might do better to
put in
a water-backed heat exchanger that can either be switched over instead
of or put in
series with the DX loops. Pumping water through 100' loops added to the
existing
bore holes will probably take a lot of pump pressure. Pumping water
through a
properly made all-metal heat exchanger will probably cause a lot lower
head for
the pump to work against.

Jon

 

[geoman]

I'm a free man and have never fired a gun.

Yep, and if it wasn't for the great shooters of years past you would be
under Indians control, keeping their fires lit at night. Then later you
would be answering to the King of England, that is if your a US citizen.
Then later you would be a slave to the liberal democrats of the south if you
were a black man, then later you would be speaking Spanish when the Mexicans
kicked your butt, then later you would be speaking Japanese after Peril
Harbor. Seems to me that its a pretty good thing that someone knew how to
shoot a gun so YOU can enjoy the benefits of their suffering for your
ungrateful regard for freedoms you never saw fit to be man enough to fight
for yourself.

Oh, the Jews in Germany weren't very good marksmen either. Hitler outlawed
guns because he knew that they were dangerous...


Rich

 

[Astro]

Oh, wow! That is a VERY interesting idea! Of course, this it how to
make a
$10,000 water-DX heat exchanger, which probably is what should have been
done
in the first place. A water loop would have a number of advantages to
the DX
system with very limited thermal field that you now have. If you were
going to
break the refrigerant system anyway to do this, you might do better to
put in
a water-backed heat exchanger that can either be switched over instead
of or put in
series with the DX loops. Pumping water through 100' loops added to the
existing
bore holes will probably take a lot of pump pressure. Pumping water
through a
properly made all-metal heat exchanger will probably cause a lot lower
head for
the pump to work against.

Jon

Great point Jon. I agree. It would be stupid to go through all that
trouble to run loops down with the others when I could just put in a real
heat exchanger. I was hoping not to break the loops to install a heat
exchanger but it would appear to be the "right" approach.

here's a question for you, and it will expose my ignorance, but I'll risk
that anyway.

If you install a heat exchanger, either in series with the current ground
loops or which can be switched in instead of the ground loops, won't that
change the refrigerant pressures in the loops as well as oil circulation
etc.? Wouldn't the compressor cycle have to be charged right specifically
for a specific setup making dynamic switching infeasible?

To make sure I'm understanding correctly, you mean a coaxial
water/refrigerant heat exchanger like here:
http://www.doucetteindustries.com/coaxial.html

And if I go with an open loop, standing column well setup (which should be
really easy to implement given my existing 950ft well), then I suppose it
might be wise to go with a cupro-nickel heat exchanger to reduce potential
problems due to water quality.

Have I got this all down?

What I'd like to do is go back to the manufacturer/installer and say
"look, rather than having to tear up the system you installed improperly
and spend days digging more wells, installing new loops, etc., I just want
you to install this heat exchanger and I'll handle the rest."

To me, that's something of a win-win. Rather than suing them and forcing
them to totally fix the system (in a way that still might not work very
well), I give them the opportunity to provide a simple fix. Then I can
experiment to my heart's content with ground loops, well water, solar
heating, or whatever, without ever having to tamper with the main system.

As a professional, what do you think? Am I just an a-hole with unrealistic
expectations or does this sound like a reasonable compromise solution?

 

[Geoman]

Great point Jon. I agree. It would be stupid to go through all that
trouble to run loops down with the others when I could just put in a real
heat exchanger. I was hoping not to break the loops to install a heat
exchanger but it would appear to be the "right" approach.

here's a question for you, and it will expose my ignorance, but I'll risk
that anyway.

If you install a heat exchanger, either in series with the current ground
loops or which can be switched in instead of the ground loops, won't that
change the refrigerant pressures in the loops as well as oil circulation
etc.? Wouldn't the compressor cycle have to be charged right specifically
for a specific setup making dynamic switching infeasible?

To make sure I'm understanding correctly, you mean a coaxial
water/refrigerant heat exchanger like here:
http://www.doucetteindustries.com/coaxial.html

And if I go with an open loop, standing column well setup (which should be
really easy to implement given my existing 950ft well), then I suppose it
might be wise to go with a cupro-nickel heat exchanger to reduce potential
problems due to water quality.

Have I got this all down?

What I'd like to do is go back to the manufacturer/installer and say
"look, rather than having to tear up the system you installed improperly
and spend days digging more wells, installing new loops, etc., I just want
you to install this heat exchanger and I'll handle the rest."

To me, that's something of a win-win. Rather than suing them and forcing
them to totally fix the system (in a way that still might not work very
well), I give them the opportunity to provide a simple fix. Then I can
experiment to my heart's content with ground loops, well water, solar
heating, or whatever, without ever having to tamper with the main system.

As a professional, what do you think? Am I just an a-hole with unrealistic
expectations or does this sound like a reasonable compromise solution?

Well, I'll tell you what I think, I think it stinks. Your will violate all
ARI and UL ratings. Secondly, good luck in finding a typical service person
who will be able to figure this out and repair it if there is ever a need.

The system was suppose to work, they said it would. They therefore should
install it correctly even if it means starting over.

For goodness sake, these are the "Experts' and they screwed up big time. IF
this company is as big and wonderful as you say they are why are you
screwing around with them? Part of being in business is to KNOW what your
doing and it is plain and simple they dropped the ball on this. If you let
it slide you won't help the next customer to not go through this nightmare.
Who cares if the guys were nice, so were you. Only people who appear 'nice'
can manipulate the elderly out of their life savings with swindles etc. So
nice has nothing to do with it, BUSINESS has EVERYTHING to do with it and if
they are a real company with 'NICE" people in it they would not sleep at
night until its fixed RIGHT.

I would tell them to bring the rig out, abandon the existing installation
and do it right or your going to the press and TV.

They sold you a system that should work as ARI and as their adds specify, it
doesn't. So either the unit is broken or THEY SCREWED UP!

You will never sell your home in the future if you do all this stuff to it,
why should you take the hammer for their mess ups?

Go after them and politely tell them to fix it right or tear it out and
refund your money.

Rich