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  • GeoThermal Heat Pump

    So, the one thing I have learned monitoring my solar system this summer is that my A/C is responsible for the majority of my electric consumption. So in the interests of conservation, I'm now studying to install a Geothermal Heat Pump for my house. The idea to pump heat or cool out of the ground rather than the air, like normal heat pumps do.

    I'm curious if anyone has any experience with Geothermal Heat Pumps. I have been studying it, and everyone says it can't be installed by anyone that is not a trained professional (even more so than Solar). Just the same, I plan to learn everything I need to know to install my own system. So, I'm wondering if anyone else installed one of systems.

  • #2
    Many of them back in the mid seventies.
    It ain't rocket science.
    The most efficient are open loop
    However water quality and Ph need to be very good for systems to last
    Most around here are closed loop with glycol.
    NABCEP certified Technical Sales Professional

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    • #3
      Originally posted by t5800512 View Post
      So, the one thing I have learned monitoring my solar system this summer is that my A/C is responsible for the majority of my electric consumption.
      Well anyone in the south already knosw that as cooling makes up for about 75% of electric use. The rest is peanuts.

      OK now I will share some experience with you and maybe save you some serious cash and heart ache. I basically live in your neighborhood. I own and operate my own architectural design/build firm and have a full staff of engineers including mechanical engineers who specialize in heating and cooling. I have also built several houses for myself over the years, and a lot of research and experience have gone into each one of them especially heating and cooling.

      Unless you have shallow ground water, a large mass of water like a pond, or a lot of land to work with a Ground Source Heat Pump is not a good candidate in TX. You will never recover your investment for the added cost of a GSHP over a high efficient heat pump. They both have the same MTBF and product life, and that added $3000 to $5000 extra will never be recovered in energy savings over the life of the product. In addition to the initial cost of the equipment and installation there are other hidden cost with a big price tag. For example the cost of re landscaping your yard after the installation. Your yard will be destroyed, no doubt about it. That is another $3000 to $5000 added on you are not taking into account.

      A good air source heat pump has SEER ranging from 13 to about 25 last time I looked, and GSHP range from 17 to 28.

      Another really good option is Ductless Split Air Conditioners. The units cost a bit more, but installation cost are lower. Ductless efficiency runs 18 to 26. However you are doing zoned cooling in rooms yu wish to cool or not, so the energy savings can be significant vs keeping the whole house cool. I wished I had gone that route, but th eunits were really expensive then and only a couple of manufactures offered them at the time.

      Hope that helps.
      MSEE, PE

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      • #4
        Ground coupled heat pumps are fine in the frozen north - in temperate or only cool climates they are of no benefit. They are not that much more efficient than a good high SEER air source heat pump to start with - just a lot more costly.
        [SIGPIC][/SIGPIC]

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        • #5
          Originally posted by russ View Post
          Ground coupled heat pumps are fine in the frozen north - in temperate or only cool climates they are of no benefit. They are not that much more efficient than a good high SEER air source heat pump to start with - just a lot more costly.
          In the frozen north, or anywhere else that the outside air gets below the temperature where an air source heat pump has enough output, they do make sense though. Once you get below the frost line or if you have a flowing water source, you have a guaranteed reasonable temperature heat source.
          And really great cooling. That part of the heat pump equation can make sense when the air temperatures are really high too.

          BTW, it really gets on my nerves to see these called geothermal heat pump systems. I am glad this thread has re-railed the OP to use the term ground source.
          SunnyBoy 3000 US, 18 BP Solar 175B panels.

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          • #6
            Originally posted by inetdog View Post
            BTW, it really gets on my nerves to see these called geothermal heat pump systems. I am glad this thread has re-railed the OP to use the term ground source.
            Correct though ground coupled or ground source can be correct.

            In cold areas where you get freezing temperatures a meter or two deep wells are really the only thing that make sense.
            [SIGPIC][/SIGPIC]

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            • #7
              From a perspective of a Northerner

              I just ordered a Mitsubishi Hyper heat air source Split unit to use in the 'Frozen North' I usually burn wood in the winter but many days even in January are warm enough to get usable heat from an air source unit. Unlike down south, the trick is to mount the outdoor unit in the sun to pick up as much heat as possible on sunny winters day. This does impact summer time operation but cooling is not required very often. In order to burn wood efficiently, its best used when there is steady heating demand so the mini split will help on days in the shoulder seasons, plus will cover a lot of my load when I am not home to feed the wood boiler. I have an old well with appropriate piping and volume to have considered a water source unit, but few companies make small units and their efficiency isn't that great compared to minisplits. Geothermal is a somewhat popular choice for new high end construction but most systems built up here are drilled well fields rather than buried loop. Ground source heat pumps are typically hot air units and require large ducting in conditioned spaces which is rare in northern construction so that also adds cost. Generally the costs for a 2 to 3 ton system installed is 15 to 20K plus retrofit of ductwork if the house uses hot water baseboard.

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              • #8
                We see a lot of closed loop well systems here. The real efficient times are at change over from cooling to heat. And vise versa. Toward the end of the seasons efficiency is way down.
                The aquifers here are pretty much very slow moving if at all
                NABCEP certified Technical Sales Professional

                [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

                [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

                [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

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                • #9
                  The well type systems up north are usually not direct ground source where water is withdrawn from an aquifer, they send down a long string of two HPDE pipes with a reverse bend on the bottom and grout it into the hole and hope the pipe never leaks. About 280 feet deep of well through mostly solid granite per ton. Heck the diesel fuel used to drill the holes would probably heat and cool a house for a couple of years.

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                  • #10
                    Originally posted by peakbagger View Post
                    The well type systems up north are usually not direct ground source where water is withdrawn from an aquifer,Not everywhere will give you a permit for that amount of ground water extraction and discharge. Ground source means from the ground rather than air source or the misnomer of geothermal.

                    they send down a long string of two HPDE pipes with a reverse bend on the bottom and grout it into the hole and hope the pipe never leaks. If the proper HDPE pipe is used and correctly done fusion welding it it ain't gonna break

                    About 280 feet deep of well through mostly solid granite per ton. That number is an engineering function that varies from site to site - more art than science it seems to me.
                    Comment in bold within the text.
                    [SIGPIC][/SIGPIC]

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                    • #11
                      I was right, there are a lot of members here that are familiar with Ground Source Heat Pump technology. And not surprisingly, everyone has an opinion on the subject. That is exactly why I posted this thread. I'm surprised that so many of you question the efficiency of Ground Source Heat Pump systems, comparing it to HE air source heat pumps.

                      I have been very interested in using open loop wells because I would like a ground source for irrigation water. But, as badly as I want a water well, I will likely go with closed loop wells for my heat pump to avoid long term problems with scale and mineral build up. Hopefully I can get the driller to give me a discount on putting in a water well when he is out to drill the loop wells.

                      I have been doing my research, and have determined that I will need four, 300 feet, closed loop vertical wells for the four tons required to cool my house. Today, I'm meeting with the first driller. If I can get the wells and header put in for $10k or less, I will probably move forward with the project. I plan to put in a split system and keeping my current NG furnace. That way, I will have a dual source for heating. I plan to install the HVAC part my self. Yep, just can't get rid of that DIY'er part of me. I taught myself HVAC 30 years ago and have all the tools and certifications required. So, the cost there will just be the wholesale cost of the heat pump.

                      This project will also qualify for the 30 percent federal tax credit. So I can get some more of SunKing's money. LOL

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                      • #12
                        Originally posted by t5800512 View Post
                        I was right, there are a lot of members here that are familiar with Ground Source Heat Pump technology. And not surprisingly, everyone has an opinion on the subject. That is exactly why I posted this thread. I'm surprised that so many of you question the efficiency of Ground Source Heat Pump systems, comparing it to HE air source heat pumps.
                        What else to compare it with? If you have a COP of 3 with an ASHP and a COP of 4 with a GSHP there is a very long payback. I looked at this in great detail for my new house a couple of years back. In a climate with relatively mild winters (we have few days at freezing) it was a loser.
                        [SIGPIC][/SIGPIC]

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                        • #13
                          Originally posted by russ View Post
                          What else to compare it with? If you have a COP of 3 with an ASHP and a COP of 4 with a GSHP there is a very long payback. I looked at this in great detail for my new house a couple of years back. In a climate with relatively mild winters (we have few days at freezing) it was a loser.
                          Agree, big mistake in TX. Just for the price of the wells you can get top of the line ASHP installed and they are just as efficient and last longer than GSHP.

                          Tell you what just pay me $5000 and I will save you $10K.
                          MSEE, PE

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                          • #14
                            The driller just left. He said he would do three wells at 400 feet each for $14K. That is manifold to the house and the whole thing. But to be honest, that is more then I'm willing to pay. I have another driller coming out tomorrow. I already have his estimate of $11.1Kk which is still over my price limit.

                            Hey Russ, do you remember how you did your ROI calculations? What did you end up doing?

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                            • #15
                              Originally posted by t5800512 View Post
                              The driller just left. He said he would do three wells at 400 feet each for $14K. That is manifold to the house and the whole thing. But to be honest, that is more then I'm willing to pay. I have another driller coming out tomorrow. I already have his estimate of $11.1Kk which is still over my price limit.

                              Hey Russ, do you remember how you did your ROI calculations? What did you end up doing?
                              This is just plain silly. You can hire a contractor to completely replace your current HVAC system with high efficiency ASHP and add insulation in your attic for less than you can drill the wells. No one trashes your property in the process. Why on God's green earth do you want to spend $20K DIY when you can get it all done for $6K professionally, and last every bit as long with same or less price to operate? Are you stupid filthy rich? Or just that ignorant?

                              If you are really R N Injunear I would not hire you. You must B A Goberment Injunear who is overpaid and cannot find a job elsewhere. Have you thought about being a TeeCher in a Sate Skool like UT? Colleges are fool of TeeChers like U.

                              I can do it all for $11K. When done we will both be tickled PINK. You get what you want, and I put $5000 in my pocket.
                              MSEE, PE

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