When you heat hard water (as in geo AC), the hardness precipitates out and coats your heat exchanger. This reduces efficiency and requires cleaning with acid.

I have a water softer that removes the hardness, using a salt cleansing process.

I think that you will find that softening that much water is not cost effective.

we're using about 100 lbs of salt a month for drinking water use... I never really thought about how much water is used for drinking vs. Geo. How much water would you guess a 4 ton system would require? I was told 6 GPM (1.5 x tonnage), but is that continuous? 24/7? Thanks.

Yes, about 6-8 gpm whenever the system is running. Perhaps 50x your current usage.

The hardness may be an issue with build up over time, however the money you will save by using what you got will pay for a lot cleaning, purging of your coil. A cupra nickle coil will be more robust in terms of water quality and the acids used to clean it.
6 gallons a minute times 10 minutes is 60 gallons times 6 ten minute segments per hour is 600 gallons per hour times a very possible 10 hours per day run time in peak heating and cooling is 6,000 gallons. Does your pit have the ability to perk that volume of water? Just some gallons for thought.
Eric

the money you will save by using what you got will pay for a lot cleaning

Let's say it takes 30 min of my time. I have to agree that I'd do this quite a few times to save $10-12K. And if it was needed too often, I'd spend a few hundred $ and automate it. Worse case, I'd do something else for AC and use the geo just for heat.

Hmm, I guess you could do it yourself, it's really not all that complicated. But you probably talking about monthly maintenance to get the best results from your system. Not sure what effect running acid through the system on a monthly bases would do to the exchanger over time.

If you are doing it very frequently (unlikely), then an inhibitor can be added to almost completely eliminate any acid effect on the heat exchanger. Perhaps the manufacturers have specific recommendations.

Load determines heat pump size and gallons of water discharged. A properly designed 4 ton system may blow through 600kgal to 800kgal/yr (you ain't gaonna soften that). The first question I have for you is how did we choose a 4 ton? What is the heat loss/gain calc for your house? Where do you live?

Regardless of size I think open loop maintenance concerns are over emphasized. In our area water is hard with iron, but having solenoid downstream of unit keeps coax under pressure and limits build up on walls. Further iron is a better conductor than insulator. where we have trouble with it is downstream of the system where it will plug drains. Using large diameter drains or venting that allow pipe to fully drain, minimize this. I've seen 25+ year old systems that never required flushing.
That said you must know what is in your water before proceeding with this project. Only a few things are "deal breakers for open loop."
j

Posted By joe.ami on 28 Jun 2011 11:38 AM
I've seen 25+ year old systems that never required flushing.
  
j

How do you determine weather a system needs flushing or not?

Troubleshooting.
Complaints may include nuisance lockouts, higher electric bills (due to auxiliary contribution or longer run times) or inability to heat or cool adequately.
Part of the troubleshoot on an open loop system would be to check flow (gpm) if not adequate one would look for adequate pressure in and make sure drain is clear. If those two things are verified then coax is suspect.
J

I have a 3 ton A/C (seized compressor) unit. The company I decided to go with (WaterFurnace System) said that a 3 ton system would be fine in the summer, but would struggle in the dead of winter. He said that a 4 ton system would run at about 70-80 capacity at a 10deg day (which we have several in Eastern Ohio). I tend to agree with the logic.

Heat loss/Gain calc, is 100m btu's/yr. 4800.00 per year to heat. 6500 heating degree days year. 40643 BTU's needed for cooling, or about 3.38 tons.

I talked to my contractor, he said the hard water was not so much a problem, and can be cleaned and treated. His biggest concern was GPM of my well and drainage of the energy extracted water. I didn't think either would be a problem. A rough estimate for my pit was 12000000 gallons capacity, and of course it perks. I have another pit, with twice that capacity if for some reason, it overflows... I can always connect the 2.

I have no iron or sulfur issues with the water. Just plain ole hard... 

I got my second estimate of $14998.00 for a Single stage 3 ton Bard, which included the vertical loop excavating cost of $5400.00. 10 year parts/5 year labor warranty.

I plan on going with the first estimate of 10858.00 for a 2 stage 4 ton waterfurnace with desuperheater with a 10 year parts/labor warranty. Going with an open loop will save appx $8800.00 in vertical closed loops excavating costs (4 ton unit). Any thoughts? high? low?...

Thanks for the comments, very helpful

Mike

I would set your well pump to provide just enough pressure for geo (maybe 10 psi) and then add a small booster pump to get 50 psi for household use. It will pay for itself in reduced pumping costs and well pump wear.

If you are interested in DIY, then there are some great bargains out there. Like < $1000/ton for the heat pump.

Posted By jonr on 30 Jun 2011 08:58 AM
If you are interested in DIY, then there are some great bargains out there. Like < $1000/ton for the heat pump.

fine show me the $1,500 total out of pockect 1.5 ton (post tax) heat pump. Or are we talking after tax credits or used.
support your opinion.
j

I'm sure you could find such support if you tried without the straw man argument. 10 seconds yields:

NEW CLIMATEMASTER 4 ton Geothermal Heat Pump downflow
WATERSOURCE HEAT PUMP
Item condition: New
Quantity:
2 available
Price: US $2,850.00

And yes there are warranty implications and as with most things, some good reasons not to DIY. One person's bargain may be another's headache.

Ahhhh,
My apologies: OP was talking about a new R410, energy star listed, 2 stage heat pump.
So yes if one prefers a unit that is 1 stage, no longer Energystar listed (no tax credit), in an uncommon (downflow) configuration, chalked full of a refrigerant that is being phased out, then of course one can get it at fire sale pricing. Last of these units came off the line ~ 2 years ago.
So yes a great bargain for someone with uncommon requirements.
j