Here is one for this fine group. 

I thought there were only two types of geothermal, ground and water for a heat pump where several vertical or horizontal trenches and coils are used.  Now I am hearing where you can use well water and thus avoid all the trenching just use the same well as what you will have to support the house.  I don't see how that can work as I thought you needed all the trenches and coils to provide a lot of surface for heat to get from the ground or pond. 
 
We have good a flow rate here.  If I have at least 15-20 gagl/permin I am told this could work. Because this type of geothermal system runs with a pull of about 10gal/per min so the reserve of 15-20 gal/per min is for domestic water use.  Basically both the geo-thermal water and home water are from the one well. You can then take the discharge water and put it back into the ground by a second well so you don't deplete your ground water source.  As I understand it, the second well needs to be just deep enough to place the water in the water table.  Have you ever heard of this? I would think a lot more people could go greener if this is for real.

 I can't afford a full geothermal system but this sounds about the same price for a higher SEER Air Heat pump.  So for a well (180ft at $2300 that is what my other house cost) and a more shallow approx $1000 (most likely too high est here), then Heat pump SEER 16 plus approx $13K. Still no matter what it will be cheaper but I have not heard of this way to go-hummmmmmmm   Any comments?????????  BTW my house is 4500sqft (to be built)

Lisa 

It is called 'Open Loop'. It is less common but works in some areas. (I have one)

You need a lot of water, ~1.5-2.5 GPM per ton, hour after hour, day after day.

The water has to be of fairly good quality - test and compare to mfg specs.

You need somewhere to put all that water when you are done with it - reinjection might work, but you'll need expert assistance with that, and permission.

Open loop is less common today, but more common overall (since late 1940's). They still likely outnumber all closed loops (DX included). With good water; performance is superior. With poor water maintenance is high.
Everything is a trade with geo so get good local advice and ask for references.
Good luck-
Joe

have a water test for iron,ph and maganese done.All of these will affect your units matainenance.if you reinject your well should be at least 400ft deep for water temp change.They call these systems standing column or pump and dump.we try to get customers to go closed loop.Seen more problems with pump & dumps than closed loop.Good luck

All depends on where you live. I have a Air Source Heat Pump and I hate it with a passion. It's ok so long as the temperature is above 40 degrees, but once it drops below freezing, it pretty useless. Newer ASPH's are suppose to be able to still operate efficently at lower temperatures, but even those have limits to how cold it can get before they are useless. Once it reachs a certain temperature outside, the heat pump shuts off and it uses resistant heat in the air handler to provide you with heating. (Expensive)

As for not being able to afford a Geothermal system, while they are not cheap, the cost savings will more than pay for themselves. Add it to your building loan for the house and pay it off over 30 years. If you perform a cost / benifit analyst, you can't afford not to install one.

TG,

I'd modify one thing you said... "Newer ASPH's are suppose to be able to still operate efficiently at lower temperatures..."

Experience has shown that while they are able to operate down to lower temps, they are not efficiently doing so. Newer ASHPs do have a lower temp. range capability, but the colder it gets, the worse they are on the electric bills.

Lisa,
If I were building a new house, I wouldn't consider anything else. I have an open discharge system, and it works great, but like engineer said, you need good water quality, and enough water. My 2 stage system uses 1.5 galllons per minute per ton on first stage (80% of time) and another .5 gal per ton when 2nd stage kicks in. I think an open system is a little more efficent than a closed loop because the water temp coming out of the ground is constant. (Mine is 51º) The quote for a closed loop was $3200 more also. I live in rural area and discharge onto the ground (sand), but am putting in a pond for it this summer. Now with the 30% credit, it is even more effective!

Hi Lisa I have a ground source heat pump installation using a single well in my new home with almost two years of experience— mostly all positive. I have a 2400 sf home of which 800 sf is an art studio with a separate zone, a 4 ton Econar system. We take heat out of the well water and then dump it right back in. We do not need a second well. I had bids for a high efficiency oil burner and full AC at $30K. Using my well (12 gpm) ended up costing $24K and I did not have to install a chimney, saving more. We have very comfortable temperatures all winter and all summer with our heat pump AC. Be aware, however, that in cold country (We are in NY in the Mid-Hudson River area) under a long period of cold the aquifer can lower in temperature to the point of inefficiency. Recognizing this ahead of time, my contractor installed a third line past the well over a hill toward a stream. When the incoming temperature drops below 39 degrees, it automatically switches for few hours. Works fine! Also I find that my electric costs go up during Dec-Feb due to the continuous running of the well pump. (about $150/month higher. I had to fight my architect, my builder and my bank, non of whom knew anything about geothermal. But I persevered and we are very happy. I am actually writing a book about this subject in order to let a wider audience know about ground source heat pumps because it is to the country's best interest plus saving money each year. Good luck Don

In between chapters of the book work on the well pump power consumption issue.

Domestic water needs to be at 30-50 psig. A geo heat pump only needs about a tenth that pressure, but a heckuva lot more flow than typical household uses. Pressurizing all that water ten times more than needed (using a pump generally less than 50% efficient) puts a huge hit on overall system efficiency

Lisa,
If you look at operating cost calcs, I think you'll begin to see that a person building a 4500SF home can't afford anything other than geo for heating and cooling. In new construction the difference between gas electric or closed loop geo systems for homes your size are 10-15K in our area. Operational cost savings is around $3,000ish (depending on fuel available, electricity cost, etc.).
You'd be suprised how often folks look at the heating system as a place to really save a buck when building a new home. Frankly not much is more important than temperature control, balance and indoor air quality in your home. Take a look at your plans and see if you can't economize somewhere else, you'll be glad you did.
J

Here's a question for engineer and anyone else regarding the well pump/high-pressure/energy consumption problem:

Since a [submergized] domestic water pump also being used for geo pressurizes the water to 35-50 psi and lifts it up to the house with low efficency can the following method be used instead:

1.  install a second 3/4 or 1" geo water source pipe in the supply well alongside the normal pipe from the submergized water pump.  Maybe use a "deep-well jet pump" pitless adaptor (a dual fitting for two pipes) for the casing connection...

2.  install a check-valve at the bottom of the geo source pipe and drill a smallish "bleed" hole above the valve (for priming). 

3. run this second pipe to the house and connect via a "T" to 1) a valve that is connected to the cold domestic water supply (high pressure water) and 2) a small "jet-pump" or simply a circulator pump with decent head.

4. this circulator pump (or small jet-pump) feeds the geo exchanger and then the dump side continues to a second [recharge] well.  The return pipe continues via a pitless adaptor down to somewhere permanently below any static water level in this second well.

5. the valve in the house would be used only to prime the supply pipe and small pump.

The standing water levels in both wells would obviously vary depending on many reasons.   However, wouldn't the small water pump only have to overcome the following flow resistances:  total pipe length friction + geo exchanger psi loss + any difference between the standing water levels.   If the standing water levels are roughly equal between the two wells then the little pump only needs to overcome pipe and exchanger resistance and would not encounter much lift [gravity] resistance.

If I understand correctly it's a combination of lifting the well water to the surface and pressurizing to a high-level is what uses so much energy.  This seems to solve both problems.  Would this work better than using a varible frequency motor well pump or a domestic use/pressure adjusting method?

Also it seems this configuration would be free from a flow direction that otherwise would be dictated by the domestic water pump.  In otherwords depending on well yields and static levels maybe we could use one well to supply the geo and dump into the domestic source well.  This way the water use load is split between the wells and not all coming from just one well.

Will any of this work?

Thump

I'm not experienced with the well plumbing components you describe so I can't comment on whether it would work.

"The standing water levels in both wells would obviously vary depending on many reasons. However, wouldn't the small water pump only have to overcome the following flow resistances: total pipe length friction + geo exchanger psi loss + any difference between the standing water levels. If the standing water levels are roughly equal between the two wells then the little pump only needs to overcome pipe and exchanger resistance and would not encounter much lift [gravity] resistance."

That part I agree with - pumping power goes way down if you only have to overcome pipe friction and head loss through the geo exchanger.

I would like to learn more about dual well reinjection systems - if water quality is sufficient such a system would combine the efficiency of open loop w/o wasting lots of water. Drilling costs would in most cases be less than for typical vertical closed loop systems.

this energy usage by a submersible pump is serious business. my two ton carrier pulls 10 amps total but the 1/2 hp well pump (32yrs old) draws about five in addition, what a waste! a grundfos sqe ajustable frequency, aka variable pressure, has a minimum of 40psi, as near as i can tell from their literature. the sqflex 30-300vdc seems to be very efficient but quite expensive. 10 psi@4-6gpm would suit me fine. our home is as warm as anyone could want so i am thoroughly sold on the concept, but would still like to reduce costs; it's a game that pays dividends.

any other ideas?
thanks;
ed c

I just started researching the use of a well yesterday. My quotes for geothermal wells are 7 wells at 300 ft. each - necessary for 14 tons. IF we were able to drill for a water well, what would it take to find a well? We have one in one area on our property but it would be too far away from where we need it. And, if we dumped it into a pond is that feasible even if pond is about 200 yds. away? And if feasible, would we have to dig a trench to carry pipe/tubing to the pond.

Just trying to find a more economical way to do this - $23,000 is more than I want to spend.

Thanks!

You can dump into a pond 200 yards away. Well drilling costs vary regionally. You could invest 1/4 to 1/2 as much. you will also have higher maintenance costs.
j

Was researching something else on the web today and came acrossed this. Dragin Geothermal in NH is HEAVILY involved in some big standing column work. They have a really good national reputation for quality work, but do not know how freindly they are to e-mails and technical coaching. A place to start for those with questions.

joe.ami,

You seem to be quite knowlegable on most of the geo topics on this forum.  My well record states that I can get 10 gpm from my existing well.  I would like to be able to use this well for a 5 ton geo plus domestic water and then dump to a drainage ditch.  Is this enough water?

Thanks,
MJ

Not a good fit. The lowest gpm for most open loop applications is 1.5 GPM. Around here I feel better with 2 gpm/ton in January. Heard a story yesterday about nuisance lock outs at a residence that was finally comnnected to teenagers/showers.
J

Would putting in a second well somewhere else on my property (8.5 acres) for the sole purpose of the geo be an option?  Who do I need to contact (county, township, etc..) to find out if dumping the excess water is allowed in my area (very rural)?  As it is, the water would ultimately flow to a lake about a half mile away if it makes it that far.   From what my water test says, my water should be good for open loop:

Chloride                              ND
Flouride                              0.33 mg/L
Hardness as CaCO3           ND
Iron (automated)               ND
Nitrate as N                        ND
Nitrire as N                         ND
Sodium (automated)          85 mg/L
Sulfate                               17 mg/L

I have a refrigeration background, but no experience with GT.  It really interests me and I want to install one this summer, but not before the appropriate research.

Thanks for your help,
MJ

Lisa,

If you are building a new home then tell your morage broker that you are using Geo. Many of they take that into consideration when calculating out your loan. Even at 27,000 the system will pay for itself in around 5-8 years depending on your climate and energy cost.

As for drilling addition wells yes it will work but you may want to reconsider it. Who you contact depends on your state. In IL you have to contact the States EPA office if you are wanting to do a injection well. They require a special permit and anual inspections. All of which add up to make doing one not cost efficent.

If I was you I would start with your local building department and go from there. I would also talk to your local distributor. If they deal with Geothermal and are any good at it, and that is a big IF, they should be able to help you with design and show you by computer modeling just how much you will save and how much loop field you will need.

My gut reaction to you saying that you are looking at 7 wells 300 ft deep for 14 tons is that you are light.  Now in your area you may have a better thermal conductivity than I do but I would still have someone model it for you so you dont get short looped. Nothing worse than expecting get savings on your heatin bill and not getting them because your backup is kicking in all the time.