wildblue
New Member
Posts:37
 |
| 20 Feb 2009 04:56 PM |
|
Hello all, newbie here.
I am planning a building concrete home using ICF in Western Washington. The home will be one story and about 2K sq. ft., sealed and insulated with the best products I can get. One goal is to use as little energy for heating and cooling as possible. My property has city water but is also has a high capacity well already drilled. I believe is it 135 feet deep and the casing looks to be about eight inches. The water is very hard with iron and manganese so I will use the city water for drinking however I want to use the well for a geothermal heat pump.
In summer, I plan on using the well water after it is used in heat pump for cooling to irrigate my gardens on the five acres. I’m thinking I will dump it in a pond and pump from the pond for irrigation. In winter, when it usually rains like heck, I do not want to dump the heat pump water to the pond. Instead I was thinking I would just dump it back into the top of the well.
Two questions: First, will the hardness of the well water with all its minerals be a problem for the heat pump? Second, does anyone see a problem with dumping the heating water back into the same well? Will the water be substantially cooler after I extract energy for heat? The under ground run from the home to the well will be about 100’ so there would be a little mitigation there.
Thanks in advance. There seems to be a lot of good info here so I will be back often. BTW, I’m looking a Pacific Polysteel for the ICF home. |
|
|
|
|
|
|
engineer
Veteran Member
Posts:2749
|
| 20 Feb 2009 06:17 PM |
|
Yes, yes and yes.
Iron is a problem for heat exchangers according to my docs - encourages biofouling. Minerals lead to scale. Open loop water is often 10 15 degrees cooler after being used for geo heat, and a 135 foot well is likely too shallow to serve as an effective standing column. The technique of returning water to the same well is called SCW - Standing Column Well, but they tend to need to be several hundred feet deep from what I've read.
Since you have 5 acres, consider a horizontal loop field. |
|
Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
|
|
|
joe.ami
Veteran Member
Posts:4377
|
| 21 Feb 2009 12:23 AM |
|
what he said
joe |
|
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
|
|
wildblue
New Member
Posts:37
|
| 21 Feb 2009 09:16 PM |
|
Thank you both. Although I don't know much about this, common sense told me my little scheme might have problems in the areas I asked about.
I think I will use a closed horizontal loop system. Are there fluids that can be used that transfer energy more efficiently than H2O?
When I move to this property I intend to put a manufactured home there and live in it while my main house is built. Then I’ll rent out the manufactured home. I mention this because my first “toy” I will buy is a backhoe. I can dig my own trenches for the loop system to save money. The subsoil is heavy clay suitable for a horizontal loop system.
The property dimensions are a rectangle 340’ x 640’. Does digging a trench all around the property line, that would be about 1900’, and laying a single pipe in it make sense? I think this would work for a three ton unit and that would be sufficient for my ICF super insulated home. Set back rules around the property lines preclude building anything near them so I would not have to worry about where the ground loop is if I choose to develop the property further. |
|
|
|
|
dmaceld
Veteran Member
Posts:1465
|
| 21 Feb 2009 10:07 PM |
|
Posted By wildblue on 02/21/2009 9:16 PM I think I will use a closed horizontal loop system. Are there fluids that can be used that transfer energy more efficiently than H2O?
Liquid sodium! Oops, that's not practical for home use. Uncle decided it really wasn't practical for the nuclear industry either. Next is pressured water, i.e., water in a system running at about 2000 psi. Oops again, not practical for home use! But it is used all the time in nuclear reactors to transport heat. Water is the best commonly available medium there is for transporting heat.
|
|
| Even a retired engineer can build a house successfully w/ GBT help! |
|
|
joe.ami
Veteran Member
Posts:4377
|
| 21 Feb 2009 10:40 PM |
|
Brine (water and antifreeze mixed) in most systems permits operation in heat pumps below freezing point of water. Of course it also derates the capacity at the same time. Each system is specifically designed by folks familiar with local conditions.
Trench sizing requires much more info.
Good luck,
Joe |
|
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
|
|
engineer
Veteran Member
Posts:2749
|
| 22 Feb 2009 07:06 AM |
|
A single loop running around the perimeter might transfer the required heat but would require excessive pump power. There are much more compact field designs which optimize heat tranfer, area, trenching, pumping power and cost.
Hire a pro who will let you do the digging. |
|
Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
|
|
|
wildblue
New Member
Posts:37
|
| 23 Feb 2009 12:13 AM |
|
Thanks engineer, although it's not intuitively obvious why the same length of trench and pipe in series makes a difference whether it is straight or routed back and forth makes a difference in pumping power.
I any event the responses to my questions have convinced me that geothermal does not seem to make sense for me in the mild Seattle area climate. I will most likely use a reverse cycle chiller instead. The free well was the thing that led me to geo in the first place. This forum is amazingly helpful. |
|
|
|
|
engineer
Veteran Member
Posts:2749
|
| 23 Feb 2009 06:54 AM |
|
Do you mean to say that you'll likely use a conventional air source heat pump?
If so, have someone run the numbers, but you may be right - in your climate air source might make more sense.
Properly installed, geo will almost certainly be cheaper to operate, though. |
|
Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
|
|
|
wildblue
New Member
Posts:37
|
|
engineer
Veteran Member
Posts:2749
|
| 23 Feb 2009 03:19 PM |
|
"although it's not intuitively obvious why the same length of trench and pipe in series makes a difference whether it is straight or routed back and forth makes a difference in pumping power. "
What is typically done is multiple parallel paths, one path per nominal ton or so. The basic idea is to get lots of pipe in the ground to maximize heat transfer. Each pipe loop might get 3 GPM or so, enough for turbulence and good heat transfer but not so much so as to need a huge pump. Then the multiple ~3 GPM flows are ganged together at the unit to provide the greater GPM it needs, anywhere from 6-20+ GPM, depending on its size / tonnage.
Hope that helps. |
|
Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
|
|
|
engineer
Veteran Member
Posts:2749
|
| 23 Feb 2009 03:24 PM |
|
That website is awfully thin on hard data.
Make sure whatever you pick is ARI-rated. Also, my understanding is that to qualify for 30% fed tax credit equipment must be energy star rated. |
|
Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
|
|
|
wildblue
New Member
Posts:37
|
| 23 Feb 2009 06:47 PM |
|
Absolutely, I’ve just begun to investigate the various systems and products. Those tax credits will definitely figure in. Thanks for your help. |
|
|
|
|
senecarr
Basic Member
Posts:211
|
| 25 Feb 2009 08:17 AM |
|
Posted By dmaceld on 02/21/2009 10:07 PM Posted By wildblue on 02/21/2009 9:16 PM I think I will use a closed horizontal loop system. Are there fluids that can be used that transfer energy more efficiently than H2O?
Liquid sodium! Oops, that's not practical for home use. Uncle decided it really wasn't practical for the nuclear industry either. Next is pressured water, i.e., water in a system running at about 2000 psi. Oops again, not practical for home use! But it is used all the time in nuclear reactors to transport heat. Water is the best commonly available medium there is for transporting heat.
Actually liquid sodium is very effective for cooling nuclear reactors IF waste storage isn't subsidized like it is now.
Besides water, refrigerants are effective at transferring heat, hence DX geothermal systems. |
|
|
|
|
dmaceld
Veteran Member
Posts:1465
|
| 25 Feb 2009 10:47 PM |
|
Posted By senecarr on 02/25/2009 8:17 AM
Actually liquid sodium is very effective for cooling nuclear reactors IF waste storage isn't subsidized like it is now.
Besides water, refrigerants are effective at transferring heat, hence DX geothermal systems.
[/quote]
Liquid sodium is probably the best heat transfer material there is, but it's very problematic when you have to open up the reactor to change nuclear fuel. There's also a very high potential for catastrophic non-nuclear explosion if the liquid sodium were ever to make contact with the water and steam that powers the generator turbines. That's why its use was dropped. The Experimental Breeder Reactor II at the now Idaho National Laboratory had a specially constructed room for the sodium-to-water heat exchanger that had a weak wall that faced the dessert. In the event of an explosion the force would be directed as much as possible to the dessert rather than to the rest of the plant.
Yes, refrigerants are very effective at transferring heat, but only in a compression/expansion process cycle, not in a low pressure single state liquid loop like water. The original poster would be wise to investigate DX as well as water loop heat pumps.
|
|
| Even a retired engineer can build a house successfully w/ GBT help! |
|
|
senecarr
Basic Member
Posts:211
|
| 26 Feb 2009 04:09 PM |
|
Posted By dmaceld on 02/25/2009 10:47 PM
Liquid sodium is probably the best heat transfer material there is, but it's very problematic when you have to open up the reactor to change nuclear fuel. There's also a very high potential for catastrophic non-nuclear explosion if the liquid sodium were ever to make contact with the water and steam that powers the generator turbines. That's why its use was dropped. The Experimental Breeder Reactor II at the now Idaho National Laboratory had a specially constructed room for the sodium-to-water heat exchanger that had a weak wall that faced the dessert. In the event of an explosion the force would be directed as much as possible to the dessert rather than to the rest of the plant.
The project never completed to turning over to an actual Integral Fast Reactor was my understanding. From a purely economic standpoint, the reduction of the nuclear materials to one that has a shelf life of a couple hundred years, instead of hundreds of thousands means even with the risks, it would be cheaper if nuclear plants actually had to pay for their waste storage, instead of it being a government run subsidy. |
|
|
|
|
arkie6
Veteran Member
Posts:1453
|
| 26 Feb 2009 05:44 PM |
|
senecarr: " From a purely economic
standpoint, the reduction of the nuclear materials to one that has a
shelf life of a couple hundred years, instead of hundreds of thousands
means even with the risks, it would be cheaper if nuclear plants
actually had to pay for their waste storage, instead of it being a
government run subsidy."
What is this nuclear waste fuel storage subsidy that you are referring to?
I work at a nuclear power plant that has been in operation since 1974. Every stick of spent fuel that was ever produced on this site remains on-site either in the spent fuel storage pools or in dry storage casks. This situation is essentially the same at most of the US nuclear power plants. See link below for more info.
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/dry-cask-storage.html
If you are referring to the DOE's development of Yucca Mountain, that has been paid for by nuclear electric utilities (and their rate payers such as myself) through mandated fees imposed by the federal government.
Refer to The Nuclear Waste Policy Act of 1982 for more info. From WIKIPEDIA: Congress assigned responsibility to the U.S. Department of Energy (DOE)
to site, construct, operate, and close a repository for the disposal of
spent nuclear fuel and high-level radioactive waste. The U.S.
Environmental Protection Agency (EPA) was directed to set public health
and safety standards for releases of radioactive materials from a
repository, and the U.S. Nuclear Regulatory Commission (NRC) was
required to promulgate regulations governing construction, operation,
and closure of a repository. Generators and owners of spent nuclear
fuel and high-level radioactive waste were required to pay the costs of
disposal of such radioactive materials. The waste program, which was
expected to cost billions of dollars, would be funded through a fee
paid by electric utilities on nuclear-generated electricity. |
|
|
|
|
geo fan
Basic Member
Posts:408
|
| 26 Feb 2009 08:10 PM |
|
After much digging I found what seems to be fairly scientific data that actualy includes these almost unknown systems ( that alone is not good )
anyway excluding 1 very low outliar GT averages around 9 KWH/sq. foot a year while the two systems included in this study that either are the same or similiar design as the one you reference is 11.5KWH/ sq.foot
This is in Ohio so likely doesnt translate to anything useful except they cost more to run there and then
best I could do
http://www.toolbase.org/PDF/CaseStudies/ResElectricalEnergyUseData.pdf
page 11,12 |
|
|
|
|
senecarr
Basic Member
Posts:211
|
| 27 Feb 2009 08:26 AM |
|
"set the fee at one mill per kilowatt-hour of nuclear electricity generated" - Wikipedia
http://books.google.com/books?id=qQu_YotSU94C&pg=PA180&lpg=PA180&dq=nuclear+waste+disposal+subsidy&source=bl&ots=6jbDi3__Q5&sig=X_dpnmpr3UH-b43y4UItZiUqboM&hl=en&ei=mvOnSfq9G4zNnQfhmLjiDw&sa=X&oi=book_result&resnum=2&ct=result
"are unlikely to cover final clean-up costs .. I've estimated a 4M/kwh shortfall."
They pay a fee for it, but it most likely doesn't cover it. The cost to cover an annuity which would actually pay the cost of storage for something for 17 million years (half life of some isotopes, so really multiples of this) couldn't possibly be covered by billions. You couldn't pay the taxes on the lands for that many years without more than that.
Now perhaps you say the land is untaxed land? Well then that is a subsidy.
|
|
|
|
|
k0wtz
New Member
Posts:27
|
| 27 Feb 2009 09:12 AM |
|
i have seen food steamers in food service torn down with no filtering in front of them and it is a terrible mess. hard water will cause all sorts of problems in equipment is not filtered. my opinion go with distilled water methonal and a closed loop. if you have a water softner you should be ok without the distilled water. i would be very careful using hard water.
bob |
|
|
|
|