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Geothermal Heat Pump
Old 11-07-2007, 05:26 PM   #1
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Geothermal Heat Pump

Anybody have experience they care to share?

Geothermal Heat Pump Consortium, Inc.
Several folks I worked with in Indiana had these YEARS ago. In addition to heating and cooling, they can also provide hot water. Unlike a traditional heat pump which exchanges heat with ambient air (and requires a backup for freezing temperatures), they use well water (open loop) or circulate fluid in a buried ground loop to exchange heat with the earth. Because the fluid has much denser BTU capacity and the earth is relatively constant temp year round, they can be more efficient than other systems.

I am especially looking for unexpected problems and ease of selecting a contractor
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Old 11-07-2007, 06:16 PM   #2
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You could ask George Bush. They are installed on his Texas ranch.

-ERD50
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Old 11-07-2007, 08:25 PM   #3
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I am building a cabin in Indiana and am thinking of using this technology. Will let you know how it goes. Let me know if you find a contractor willing to work in southern Indiana.
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Old 11-07-2007, 08:47 PM   #4
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It can be a very attractive technology. It saves a lot of energy. There are a few approaches to exchanging heat with the ground :

- Bury a large loop of PEX (plastic pipe) either horizontallly or vertically. These "closed loop" systems require a lot of digging and installation costs can make them prohibitively expensive (payback on the order of tens of years)

- same as above, but the loop rests ont he bottom of a large pond or lake. Far less expensive to install than above, but temps won't be as favorable as deeper ground coupling.

- Pump out well water, exchange the heat, and re-inject the well water in a different well nearby. This can save a lot of money and be a very attractive approach if the water quality is good. Very hard water will cause the heat exchanger to scale up and cost big $$ in maintenence. This approach is not allowed in some areas (due to possibility of contaminating the groundwater used by everyone else.)

- Pump out the well water, exchange the heat, dump it into a river/surface point. Cheaper than above, but illegal/irresponsible unless you are lucky enough to live in an area with tons of extra subterranean water.

- Single casing well exchange (I've forgotten the actual name of this): If you've got a really deep well (typically 500+ feet for the heat/ac needs of an average home) you can take water out of the bottom of a well, exchange the heat, and dump it back into the top. It will heat up/cool off back to ambient temp by the time it reaches the bottom again. This approach is NOT a common one, but it does work and can be done inexpensively (again, if your water quality is good and the well is deep enough).

Also, there are "Direct Exchange" units that don't use water/glycol in the ground loop, they send the actual refrigerant into the ground through a loop. Technically, these are more efficient (one less exchange of heat), but they can be more costly, and I didn't get the feeling that the approach was likely to be as reliable as the more common method using water/glycol earth exchange loop and a flourocarbon-refrigerant loop for the compressor/internal heat exchanger.

The technology of groundsource heat pumps is mature and it works. The biggest problem is that each installation requires site-specific analysis/engineering, so you need a good, qualified dealer/installer. These are not common, and it takes some work to know if the installer reallly knows what he is doing (they all have very glossy brochures and impressive sales pitches). I looked into it, wanted to do it, but I could not find a good local dealer and the cost/payback numbers just didn't work out.

Good luck!
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Old 11-07-2007, 11:28 PM   #5
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Quote:
Originally Posted by CybrMike View Post
I am building a cabin in Indiana and am thinking of using this technology. Will let you know how it goes. Let me know if you find a contractor willing to work in southern Indiana.
i had a co-worker once from finland who said the setups you descibe
were used quite a lot in finland.
it might make sense to look at products made by
finnish / swedish companies.
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Old 11-08-2007, 09:14 AM   #6
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We have a closed loop system and love it. Located in Minnesota so the heating is more important to us than the cooling.
Payback for us is between 4-7 years.
From Feb - spring last year our gas furnace back up was not used (do to the hookup not being turned on) and while it got a little chilly (58-60) nothing unbearable. It handled all the heating until the outside temp got below about 0-5 below zero.
Our house also has highly efficient insulation. With less insulation the geo system would need to do more work so your results will vary.
If you go with a closed loop and have the space for a horizontal trench it is much cheaper than digging the vertical holes. You need about 100ft trench for each ton of heating/cooling.
If you have moist sandy soil, that holds the heat better than dry, clay soil so you will get better results.
The efficiency the second year is turning out to be better than the efficiency the first year. Not sure if that will hold through the entire winter, but we shall see.
Our system heats our infloor radiant system, water heater and helps warm and cool the A-coil in our furnace so when it is needed it takes a little less energy.

Also check with your local power company. Ours agreed to give us off-peak pricing all day for using a dual fuel system (heating, water heater, cooling all use geothermal primarily and only draw electricity/gas when geo is insufficient). So we end up paying 5c/Kwh for those as well as the electric pump.

Our builder worked with the contractor so I can't tell you much about how easy it is to find one. However, make sure they have done it before, preferably a number of times.
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Old 11-08-2007, 09:24 AM   #7
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A friend in NW OH put a ground loop system in 10+ years ago, says heating and cooling is almost free. It was worth while for him because he is a backhoe operator and did all the outside work himself. His whole front yard was loops of trenches, would have been very expensive to hire the work done. I considered both the loop and open well approach. Ground is to rocky where I am for yard loop and illegal for open well so I keep paying high heating bills.

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Old 11-08-2007, 12:03 PM   #8
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You could ask George Bush. They are installed on his Texas ranch.

-ERD50
Are you sure? I though Al Gore was the ecologically minded guy with the energy efficient house and all that.......
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Old 11-08-2007, 12:43 PM   #9
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Are you sure? I though Al Gore was the ecologically minded guy with the energy efficient house and all that.......
You are probably just baiting me, but just in case anyone is not aware of this....

A Tale of Two Houses - Netlore Archive

Quote:
A Tale of Two Houses - Gore vs. Bush

Netlore Archive: Email flier compares the eco-friendliness of Al Gore's Nashville, Tennessee mansion to that of President George W. Bush's ranch in Crawford, Texas


Description: Email flier
Circulating since: March 2007
Status: Mostly true

Al Gore controversies - Wikipedia, the free encyclopedia

Quote:
Use of energy in home

In 2007, Gore came under criticism from the conservative think tank Tennessee Center for Policy Research.[18] The organization issued a report which said that during August 2006 Gore's household consumed 22,619 kilowatt-hours more than twice the electricity in one month than an average American family uses in an entire year......


In an earlier article in USA Today, Peter Schweizer argued that "according to public records, there is no evidence that Gore has signed up to use green energy in either of his large residences. When contacted Wednesday, Gore's office confirmed as much but said the Gores were looking into making the switch at both homes". [21]

Response

TIME quoted Kalee Kreider, a spokesperson for Gore, saying that the Gore family tries to buy green energy to reduce their carbon footprint. She continued to say that since the controversy, the Gore family was "in the midst of installing solar panels on their home, which will enable them to use less power." She also added, "They also use compact fluorescent bulbs and other energy efficiency measures....
Note the political posturing in that answer. He never denies actually using 20x the energy that the average home uses, just tries to explain it away. Good thing he uses a few CFLs, he might be using 0.001% more energy without those

-ERD50
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Old 11-08-2007, 12:47 PM   #10
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You are probably just baiting me
Uhhhhhh...... I'll try to be more obvious next time!
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Old 11-08-2007, 02:24 PM   #11
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Good thing he uses a few CFLs, he might be using 0.001% more energy without those
Actually ERD if the Gore house is typical in it's percentage used for lighting (20%) then the savings would be about 15%.

I agree with your base points, just not the exagerated .001%.

Bush is smart, geothermal energy is far more cost effiecient than other alternative energies. I also applaud him for his work when he was the Texas gov. in increasing the amount of energy from wind power.

So to bring this back to the original topic, I would highly recommend geothermal before solar. If you want to go solar, and have not gone the geothermal route, solar water heating systems are much more cost efficient than solar electricity.
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Old 11-08-2007, 03:14 PM   #12
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Hmmm... can this be done on a standard tract house with not much land??

And how much does one of these sytems cost?
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Geoexchange experience
Old 11-08-2007, 04:26 PM   #13
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Geoexchange experience

We had an oil fired furnace and had the tank filled in Oct. 2005. Nearly $600! Time for a change.
Our house is a 2 story, 3 bedroom built in '79 with all new windows in 2000 It is about 2000 sf.
We decided on a Waterfurnace unit with the heat/cool coil where our old A/C coil was mounted (let us use the original ductwork and the oil furnace for a backup) The closed loop system uses water and propylene glycol in the ground loop. It is a 4 ton dual capacity system. We didn't have room for the trench type installation on our lot (takes about 3000' of pipe) and had to go with 4 180 ft. wells with loops of poly pipe grouted in. It was an incredible mess, luckily in the winter - saw the same thing on that Dirty Jobs show - the drillers end up covered in mud.
The pipes are all connected and brought into a corner of the basement near the floor where they go through a couple little circulating pumps and through the Heat pump. The output of the heat pump is one of the new freons, and circulates through the heat exchanger in the furnace plenum, just like the A/C did (cold in summer, hot in winter) An added benefit is a desuperheater circuit that takes excess heat from the heat pump and cycles it through the water heater. The water heater meter doesn't even run in the winter time.

The system is quiet. We set the thermostat to heat and leave it about October 15th.

Cost was about $13K, with the largest expense being the well drilling and ground loop installation.

5yr average fuel oil purchase was 763 gal. (something over $2K/year now)
Electricity cost projected for 2007 will be 1563 vs. $1029 in 2005, or $534 extra to run the heat pump.
Savings this year are about $1500 over oil at $2.90. Who knows where it will end up.

Steady state payback is about 8 years assumming no maintenance on either system. A friend has a similar system over 10 years old with no maintenance. The oil burner used to take about $100/year average maintenance, but that was when I was working and somehow it knew when I was out of the country. I'll probably not have an issue with the oil system. It ran a total of about 2 hours this year.


2006 operating costs were $1312 (less 2005 electric of 1079)=
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Great Responses....keep em comming
Old 11-08-2007, 04:59 PM   #14
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Great Responses....keep em comming

Thanks to all.

Walt.......your response on another thread was the reason I posted to begin with. Glad to hear you are still satisfied with the system

There's no way the operating cost could be "practically free" as you must pay electricity to run the pumps and compressors.

The figure I've seen on closed loop system piping is 1000' per ton (not 100)...will check on that. We need a closed loop system and probably have adequate lot size.

Water Furnace is a company that specializes in the equipment and they are located in Indiana (Elkhart or Ft Wayne, I believe)

We've experienced a 60% increase in electric rates, so we were initially just looking at replacing our 80gal electric water heater with gas, but 1st quote was 4k because we need the forced vent system. Now Im wondering if it would be cost effective to replace heating and cooling systems together with the water heater. Our home has a 2 zone HVAC system which is gas on the 1st floor and heat pump on the 2nd floor that totals about 5 tons of cooling. Might be possible to re-use the indoor heat pump equipment. I also like the idea of keeping the gas furnace for backup. I would consider if payback is under 8 yrs. With fuel cost going up the payback becomes more favorable. I live near DC so heating and cooling are both significant.
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Old 11-08-2007, 05:35 PM   #15
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I did follow up on the comment about the length of piping required per ton and it seems that the standard is approx 1000 ft/ton of heating/cooling....but there is a "slinky" piping layout that compresses 1000 ft of pipe into a 100 ft trench thereby reducing the excavation costs.
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Old 11-08-2007, 05:43 PM   #16
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Jazz,

It was a pretty easy decision for us because our A/C and furnace were 25 years old and we had been replacing water heaters every 8 years, or so.
I didn't mention that we got a super insulated Marathon water heater with a lifetime warranty (the rural electric utility just across the border in South Dakota was installing them free for their customers to save electricity, so I thought it a pretty good endorsement). We went from a 50 gal. to an 85 gal. to take advantage of the "free" hot water from the desuperheater.
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Old 11-08-2007, 05:47 PM   #17
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My contractor said he didn't usually do the slinky thing because its easier and faster to just do a 6" trench with a big Ditch Witch vs. digging the Panama canal in the yard. We're in a little town surrounded by rich? farmers with lots of land to cut trenches through
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Old 11-08-2007, 05:56 PM   #18
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Texasproud,

Forgot to mention, If you do wells, they need to be at least 15 to 20 feet apart to not interfere with each other. If you don't have at least 150 feet of easy drilling (no bedrock), it gets more expensive. If you go deeper, you need stronger pipe to take the extra pressure, and again, it gets more expensive. The only advantage to wells, is that the average temparature deeper is warmer (55 degrees where I live), so you need less pipe.
Did I mention that as soon as the pipe is down the hole, they fill it back up with a grout around the pipes to enhance conductivity and prevent contaminating the aquifers?
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Old 11-08-2007, 06:02 PM   #19
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Texasproud,


Did I mention that as soon as the pipe is down the hole, they fill it back up with a grout around the pipes to enhance conductivity and prevent contaminating the aquifers?
I was wondering about that part! And also is there any leak detection built in?
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Old 11-08-2007, 06:20 PM   #20
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Actually ERD if the Gore house is typical in it's percentage used for lighting (20%) then the savings would be about 15%.

I agree with your base points, just not the exagerated .001%.
Interesting thread here, I don't mean to side-track, I'll just explain and then go back to listening.

Sorry Zathras, it was meant as an exaggeration, I should have used a smiley-winky.

But not such a big exaggeration, really. Wiki says lighting accounts for 9% of household energy, not 20%. CFLs can only save a percentage of that 9%. The really important part is that the number used in that comparison of Gore's house is for ALL energy usage (not just electrical), including the natural gas to heat the home and pool. It stands to reason that that is where much of the increased energy goes, so CFL energy saving would be an even smaller part of that total.

Sorry for the interruption, carry on.


Back On Topic:
most of my yard is a septic field, the wells around here are getting drawn down and are very hard, iron heavy water - not sure I want to rely on that going forward (although I realize the water is being returned). Can they put these geothermal fields in and snake them through septic fields?

-TIA - ERD50
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