Geothermal Heat Pumps

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On the recent suggestion that I invest in a windmill to suppliment my energy needs, my research directed me toward a nifty little 1 kW unit from the Danish company NEG Micon. But, by the time i figured in the "extras" like the pole and the inverter, project costs approached $10k.

Current Passive Solar installations seem to be running around 8 dollars per watt.

What gives? On paper, both of these options seem pretty pricey (given I'm already on the grid). It would seem that both these technologies need at least a decade before one can expect some returns on their investment.

What i read today is that GEOTHERMAL HEAT PUMPS can pay for themselves in 3 to 5 years. Is this true? If so, why do we keep hearing about the more "outwardly visable" technologies that exploit the sun and wind.

So. Does anybody out there have some first, second, or even third hand experiance with geothermal? This sounds like a lot cheaper way to get involved in the reduction of resource dependency, and id appreciate any experiances you'd care to share.

¥

-- Chris in Mich (chackbardt@industrialvac.com), March 04, 2002

Answers

There is info on these at the alternative energy catagory at the bottom of the question page.

-- mitch hearn (moopups@citlink.net), March 04, 2002.

Are you looking to provide electricity with the heat pump, or just heat?

Here's one 'issue' with geo-thermal. That water down there is a drinking water source for a lot of people. I get kinda nervious with several 100 folks drilling 2 wells into it, and curculating water up & back down again. I'm wondering what else is going along down the hole, oil traces, bactteria, antifreeze from a bad heat exachanger, ????

Good idea, but I am concerned about people putting water back down from the surface again.

--->Paul

-- paul (ramblerplm@hotmail.com), March 04, 2002.


I am in the process of designing & building a house in the country. My electric co-op did a cost comparision(free of charge), geothermal against all electric. Building exterior walls with 6 inch studs, blown in cellouse insulation, double pane windows & wood stove back up--geothermal IS NOT cost effective in my situation. You will get more bang for the buck by super insulating, also insulate slab from the ground, air tight, etc. Larry in OK

-- Larry in OK (Nuts4bees@aol.com), March 04, 2002.

Geo Thermal Heatpump is a closed loop system - Water is enclosed in a pipe under small pressure..does not use subsurface water directly.

-- milam (milamgerick@juno.com), March 04, 2002.

Some geothermal systems DO use ground water. However, I believe that is illegal in many states.

I've been to a couple of alternative energy home tours that had houses with geothermal heating. They have tubes run through the ground (this can be horizontally or vertically) with liquid in the tubes. I don't think it's water, I think it's something like propylene glycol. Both of these places were using the geothermal heat to heat their homes, however. It didn't produce electricity. In fact, the heat pump USED electricity. So perhaps this is not what you are interested in?

-- Joy F {in Southern Wisconsin} (CatFlunky@excite.com), March 04, 2002.



Duh, ok, the buried tubes in the ground, not going down to the water table. Gotcha.

Up here in Minnesota it's not popular. We need to burry water pipes 6' deep to stay below the frost line, so to collect heat would need to go even a bit deeper I suppose - and need a long trench to get enough heat transfer. Natural gas or LP or fuel oil becomes cheaper than the electricity for the heat pump to make all those degrees. Or rather, to transfer all those degrees.

--->Paul

-- paul (ramblerplm@hotmail.com), March 05, 2002.


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Mitch Hearn - Tx.

Paul - Valid points, all. But if I installed a system it would be a of the "horizontal closed loop"-type -- I guessed i should have noted that, as the only potential source of pollution in such a set-up would emanate less than 3m below ground level.

Larry in OK - Interesting -- I'd like to hear more about there procedures. ---But i do completely agree with the 6 inch studs, only problem is, i'm living in a 100 year farm house with a gimpy furnace. If i've got to replace my furnace anyways, why not also consider a system that would lessen my fuel dependency, supply free hot water (in summer) and offers long-term-viability enough to positively influence my homes eventual resale. This ain't "the place" yet, but i'd still like to make improvements.

milam - Paul's correct - some geothermal systems place the fluid lines coiled in a pond, and some install wells directly into an underlying aquifer --- i just wouldn't consider either of them.

Joy F - Good points, Joy. I realize these things use electricity, but my preliminary research indicates that heat bills can be substantially reduced enough so that the system pays for itself in 3 - 5 years. That's huge -- and a much quicker turn around than either the wind or solar alternatives.

Paul - Here's a page i came across yesterday via the U.S. Dept of Energy. Here's the essence.

Case Study—Minnesota Located in the middle of Minnesota—where temperatures can range from 90°F (32.2°C) with 95% humidity in the summer to -18°F (-27.8VC) in the winter—Dennis Eichinger's 3,400-square-foot home averages a little over $44 per month in electricity bills. The owner has been very satisfied with the unit's quietness, high quality, reliability, and low maintenance. House guests also marvel at the comfort level of the house—they don't feel any drafts, just an even temperature throughout the house. The five-ton ground source heat exchanger connects to five horizontal Slinky™ loops, totaling 3,000 feet of pipe, buried next to the home at a depth of eight feet (2.4 meters). GHP technology heats and cools as well as, or better than, conventional systems, even in Minnesota's extreme temperatures.

-----Any other insights would be appreciated.

¥

-- Chris in Mich (chackbardt@industrialvac.com), March 05, 2002.


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Sorry, that post didn't include the link that i tried to HTML -- http://www.eren.doe.gov/erec/factsheets/ghp_homeowners.html

-- This discussion thread makes me think that geothermal is simply the "Ugly Duckling" of the alternative energy scene. ¥

-- Chris in Mich (chackbardt@industrialvac.com), March 05, 2002.


I'm considering one, too, I'll let you know whatever I find out over the coming weeks. Oh, and here's a link to an animated snippet that demonstrates the basic set up (even though you seem to have a fairly firm initial grasp).

http://www.ghpc.org/about/movie.htm

-- suspecterrain (suspect_terrain@gmx.net), March 05, 2002.


Chris~

Being from OK are you familiar with Doug Rye? He has a web page, www.DougRye.com. He is a huge proponent of cellulose insulation, geo- thermal heat sources and even has a service that he will help you to design your house to be most energy efficient. BY this I mean, where to place windows, what type of energy source is best, etc. He will be in NW AR in April, in Fayetteville. I think his schedule is on his website. He is brought in a lot of times by electric coops because he has really helped people cut back on heating/cooling costs. We know a guy in Fayetteville that he helped who built a 4000+ square foot house. His electric bill has never been over $80. I have a 100+ yr old house, 2800 sq.ft, and mine is always over $100!!, plus I have a gas bill to add to that. Look him up, I think you will find it interesting.

-- Ivy in NW AR (balch84@cox-internet.com), March 05, 2002.



Friends in Michigan have it. Their bills are over $200 a month. Mine, on the grid with electric and natural gas, averaged $60 a month last year for a 1700 sq. ft. poorly insulated 39 year old ranch. We went to an open house of a newly built home and it had this HUMUNGOUS water heater in the basement and there was water all around it. I personally wouldn't touch the system. Build your home super insulated. I can just imagine how low our bills would be if our home was built with current energy saving products, super insulated and passive solar.

-- Sandy Davis (smd2@netzero.net), March 05, 2002.

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Suspecterrain - Sounds good -- email me.

Ivy - Thanks Ivy, this guy appears to have a decent handle on things -- but i'm not in OK, i'm in Michigan. I'm just really suprised how few people show interest in this (especially given that my monthly heat bill is pushing $180). I checked out DougRye.com -- it was good to see a guy who's installed a bunch of these systems and it only fuels my desire to get more info.

I mean, shoot-doggies, I'll be laying in a super-large garden spot come this spring and it might just be the ideal location to lay in a piping grid. Nonetheless, thanks a load for leaving me the link, and mostly, for your additional thoughts.

¥

-- Chris in Mich (chackbardt@industrialvac.com), March 05, 2002.


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Sandy Davis - Wow! $200 per month? Do you know how old their system is and how well insulated the structure is. No matter, it's still good to hear the "other side of the coin" with the leaky basement beasty. I already got a wet cellar, however, so maybe i should just add a pool liner, install the geothermal, and rosin-up the rubber ducky for winter-dippin' in underground pond.

¥

-- Chris in Mich (chackbardt@industrialvac.com), March 05, 2002.


I've got one; i love it. It's 395% efficient, here, with my 52 degree groundwater. That's for heating; I don't have the figures for aircon, but I almost never need aircon anyway. Yes, I use groundwater. I was going to drill a return well, but since my well is flowing artesian, it seemed pointless, since it would just run out on the ground anyway.

The most important point about geothermal heat pumps is that they don't even NEED an "emergency" heat strip. Mine doesn't have one, and the only reason to have one at all is in case you're system is down for repairs, so you can still have heat. (I have a wood stove for heat/backup heat.

The geothermal heat pump, at least the ones thats use groundwater, as mine does, are equally efficient regardless of the outdoor temperature, unlike "regular" heat pumps.

Regular heat pumps have two big problems in cold weather, like from 35 or so degrees on down. They lose efficiency, since they are "pumping" the heat out of the outsied air. Also, depending on the relative humidity outside, they have to run the aircon cycle as much as ten minutes every half hour to defrost the outdoor unit. To make up for the cold air being blown at you in the house while this is happening, they run the auxiliary heat strip. REsult: extreme lack of efficiency.

Since the geothermal (ground water variety) heat pump is pumping heat out of a source (the well) which never varies appreciably, if at all, the efficiency remains very high.

The other cool thing is there is no outdoor unit to get weathered, to make lots of noise, etc.

Although I certainly agree that this source of energy is merely a conservation technique, rather than a power source, it's a great conservation technique, and I recommend it highly until such time as you can go solar. (BTW, I consider my high efficiency wood stove "solar"! Wood merely stores energy it acquired from the sun through photosynthesis.

I don't share y'alls concerns, either, about polluting the groundwater by returning the water from the heat pump. It's highly unlikely that any weird material would ever get into this water; it's as likely that you'd pollute the groundwater by having your subpump leak oil. Or any number of things.

-- joj (jump@off.c), March 05, 2002.


Sandy, what you're saying does not sound like it's related to a geothermal heat pump.

-- joj (jump@off.c), March 05, 2002.


joj: It's highly unlikely that any weird material would ever get into this water; it's as likely that you'd pollute the groundwater by having your subpump leak oil. Or any number of things.

Where I live, they _are_ concerned about such things. You would have a difficult time even getting liability insurance on a loop groundwater sysyem here, and you would not get a permit for the wells without the insurance.

Anyhow, your system sounds quite nice. Where do you drain the water off to? 'Here' it would need to go underground somehow, a surface drain would freeze solid. For that matter, do you have a guess as to how many gallons the thing takes to heat the house?

Where I live there are no dependable springs or such. If there were, couldn't use them for potable water anyhow - more regulations against that. It is interesting to see what is actually allowed in other parts of the country. I'm actually in a very rural county, but Minnesota is quite strict, and my county is moreso.

--->Paul

-- paul (ramblerplm@hotmail.com), March 05, 2002.


Doug Rye has the right idea & good info. i am building my super insulated house in OK, zone 7a (10 to 5 degrees) this week we had our coldest day of this winter, 3 degrees with wind chill added to drop it more. with the blown in cellouse, double pane windows, flouresence lights, insulating the slab from the ground with blue board, etc, i would save less than $300 a year, comparing gethermal to all electric with all the energy saving features on both systems. i will pass on gethermal. spend that money on a wood heating stove, back up generator, metal roof, etc. my building site has large hardwood trees, shade in the summer, leaves drop for more sunshine in the winter. the house will have full length porches on 2 sides, 18 inch wide eves for more shade. energy saving features are more cost effective with new construction. i would rather spend $ on blown in cellouse insulation one time & save every year after that. research your needs & budget ! enjoy, Larry in OK

-- Larry in OK (Nuts4bees@aol.com), March 06, 2002.

joj - Thank you, that was very informative. You wouldn’t care to share any of the project costs, would you? With just a heat sink, reservoir, and pump (I’m guessing), it wouldn’t appear to be all too much. Also, in which climate are you located?

Larry in OK - Yes, sounds like that’s just what you’ve done. If I were building new, things would be simpler – trying to retro this old farm house’s what’s got me wiggin’ out.

¥

-- Chris in Mich (chackbardt@industrialvac.com), March 06, 2002.


Hi Chris,

You have lots of good info here...let me just tell you of my experience...mostly positive and costs.

1. Built a 3K square foot house on the farm with 6 inch insulated walls and 36 inch insulated attic in South Dakota. 2. Researched and installed two Econaire geothermal heat pumps for zonal heating and cooling. The pumps, plumbing, ducting, controls, installation, etc was 14 grand vs 7 grand for a conventional propane system. 3. The well was 2 grand with about 4000 feet of trenched water line and many field hydrants for irrigation of the nursery beds. The well supplied the heat pumps and the exhaust water was run into our pond...this is an open loop system and may not be possible in many places...for us it worked and the well was more than adequate for all of our water needs. The house water was rural water not well. 4. Our total utility bill was 194 bucks a month. This was for heating and cooling the house, all of the farm/nursery electricity...stock tank heaters, lights, incubators, the shop, etc pumping water, ventilating the greenhouses (3) and running greenhouse lights some months.

When I ran the projections, I figured the pumps to payback in 7 years. They paid back in more like 2 years because of the cheaper electrical rate that we got by being a mostly electric household and that savings was passed on to the nursery and farm part because it was all on the same meter. The electric company knew about this too so it was not some sneaky deal.

Finally, we ended up selling that house and a few acres around it for a premium because of the heat pump installation and so actually they were largely free for us if you count the reduced electrical rates as interest on the 14K capital investment considering that we took about a 15K premium on the house because of the pump installation.

We had one leak develop because of our well's water chemistry and we added high volume treatment cartridges upstream from the pumps at an added cost of about 30 bucks a month. Still well within the cost recovery levels predicted and well within those actually realized.

Finally, the house was more comfortable than any place I had ever lived. Of course it was the only new place where I had lived too. If cooling is a big part of your need, go for it. They are much more efficient coolers than heaters and they are better heaters than any combustion type heater out there.

Oscar

-- Oscar H. Will III (owill@mail.whittier.edu), March 06, 2002.


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Oscar - Thanks a lot, that sounds excellent; The resale value and quick pay-off time are (my percieved) key benefits to such a system. Sounds like you put together quite a usefull system, and since you went and sold it off, I'd also like to hear what (if any) suplimental energy you are incorperating now. Cheers.

¥

-- Chris in Mich (chackbardt@industrialvac.com), March 06, 2002.


Hi Chris,

We currently split our living between a home provided by my wife's employer and a 1780 house on one of our farms. The kids are all in the world and the smaller old house is our favorite. It is heated with forced hot water and does not cost much to heat. It is not yet cooled but that has not been a problem so far. I probably would avoid installing any forced air system in that house because it is of post and beam construction and so impossible to duct without soffits and false walls.

If we ever build again, or move to a place where we don't care about the historical structure of the house geothermal would be high on my list of possibilities, especially where cooling needs were significant.

Oscar

-- Oscar (owill@mail.whittier.edu), March 06, 2002.


Hi, Paul, my water drains out into a "fake" creek I built, thence into a pond. I designed the heat pump's outlet so that it won't ever freeze. It is buried below any likely freeze level, then drains downhill (still underground) until it daylights. Thus, there is never any water standing in the part of the pipe which is above the frost level. It has never been a problem. If it ever were to freeze, the electronics in the system would shut it off. This has happened a few times when the main solenoid has gotten stuck in the closed position, due to sediment in the water. I recently bought a whole house water filter, which I plan to install when the job reaches the top of my "honeydoo" list.

My heat pump uses four and a half gallons per minute when it runs. It's a "three ton". It runs for an hour or two, depending on the outside temperature, in order to bring the inside temperature up to 70 degrees "while we sleep". Thus we awaken to a warm house. The heat pump automatically turns itself off at seven o'clock a.m. as that's how I set the thermostat.

If I'm going to be around for the day, I build a fire in my "high efficiency" wood heater. Otherwise, I don't have heat until the next morning, usually. So I guess the heat pump uses about 400 gallons per day, on average, during the winter. Total summer water use by the heat pump so far has been very low, since we've only needed aircon about five hours per year. So total water use for the entire summer is about 1500 gallons.

Wow, I had no idea that Minnesota had such stringent regulations. How do they justify not using a spring for a water supply? Here you can use anything you want, as long as you don't take water that belongs to someone else with older water rights. Since springs are generally more susceptable to surface water contamination, some folks run spring water through a chlorinator; others don't. There are no rules about this, unless at least three households are supplied by the same spring. By the way, there IS no antifreeze in this system. Basically, the water just goes through some coils. It's pretty much like a big refrigerator., the way it works, except for the water being substituted for the air coils in the back of the refrigerator.

Chris, the entire system cost $6700. The heating contractor supplied all materials and labor, except for I saved several hundred bucks by installing all the laterals, (which is easy, as they are flexible) and floor registers. My heating contractor does all metal ducts, by the way, which adds to the cost. He refuses to use those fiberglass ducts, as he says they "always" end up breaking down to some extent, and putting little fiberglass fibers into you lungs.

If I'd have had to put in the buried lines, he tells me, I'd have had to add five to ten thousand, depending on how hard the digging was (and it would have been at the high end here, with my "soil")

I'm in a pretty mild climate, in SW Oregon. Winter temps average 40-50, though weather in the 20's is not uncommon in the mornings. Very little insolation between Oct 1 and March 31, unfortunately, but we get lots of rain instead.

Summers are relatively hot, but very dry. Full sun 90+% of the time, between May and 1st of Oct. Low humidity results in major diurnal temperature fluctuation, which is why I rarely need aircon.

Highs typically in mid nineties, with a few days between 100-110, but the lows, most mornings are below 60, and often close to 50. I cool off my house with a "whole house" fan. It's basically the same as the "attic fans" of my youth, but not as nice, since it is ony three feet in diameter, so it spins much faster, and is noisier. If I didn't have the need to pee every morning at five o'clock or so (typical old male fart syndrome) I'd put a timer on this fan to turn it on at that time. It cools the house ten degrees in an hour or so, when it's that cold outside.

The house I built is earth sheltered on three sides, downstairs, and exceeds "super good cents" standards. Even without aircon, the house almost never gets up to 80 degrees inside. It also almost never gets below 65 after sitting overnight with no heat sources running.

I realized when I built it that it was not "cost effective" to go to the extra expense I went to in building it; however, to me, there are more important things than the bottom line. Things like clean air, clean water, preserving energy resources, etc.

I mean, when you buy a new stereo, or something, do you look for "cost effective"? Or do you look for quality? Same is true for me in energy efficiency. Go solar!

Oscar, I'm glad you brought up the issue of water quality. I recommend getting an analysis done, though I did not do so. My heating contractor "threw in" a nickel copper heat exchanger just to be on the safe side. I've since done a water analysis (for a spa), and found out that our water is near perfect, with pH and hardness levels almost exactly in the middle of the "ideal" range.

If you get the water analyzed, like I should have done, you will be able to decide if using an open loop is even a good idea; a closed loop is less efficient in terms of heating and cooling, but if the water damages the system, you still might be better off with a closed loop system, since it is filled with non corrosive liquid, or so I'm told.

-- joj (jump@off.c), March 07, 2002.


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Joj - $6,700 is still a fair piece change when considering you didn't need to do much in the way of excavation. But still, i'd wager that your investiment will pay dividends in half the time that one might releaize through the "more conventional" avenues of wind turbine and photovoltaics. Thanks for sharing.

¥

-- Chris in Mich (chackbardt@industrialvac.com), March 15, 2002.


Minnesota has some very strict conservation & health laws. I am always amazed at what folks are doing here on this forum - we can't get away with 1/2 of the stuff you folks are doing! They want to preserve the enviornment here. You can't disturb a spring because it is a natural wetland & Minnesota has a no net loss of wetlands rule since the late '80s. Also the health concerns of surface water, they won't allow it on those grounds - too easy to contaminate the water.

The magazine 'Farm Talk Show' had an article about a ground water loop heat pump running in South Dakota for many years - there's a cold climate too. ;) Do a web search, they do have a web page.

--->Paul

-- paul (ramblerplm@hotmail.com), March 15, 2002.


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