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OT - GeoThermal Heating & A/C

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  • OT - GeoThermal Heating & A/C

    Well, I'm getting ready to build my retirement home and am looking at the benefits of a Geothermal heating & AC system. I have plenty of land for the "Loops" and the soil is all sand. With the Government rebates the cost extra between a conventional system is about $4000. I have Natural Gas in front and will probably still put Natural gas in the house for cooking range, hot water tank, gas grill, gas furnace, standby generator. I'm looking for the good, bad, and ugly of these systems. I'm looking at a waterfurnace series 7 unit.

    I will be waiting your response - also do you think the 2nd water tank to preheat the house hot water in the summer really is that big of a savings for the additional costs?

  • #2
    I installed a geothermal heat pump in the last house I built in SC. It used water from a deep well, and the water was dumped into the nearby lake. I lived in the house from 1987 to 2004. I absolutely loved the system. It was incredibly quiet, very efficient, and trouble-free.
    Any products mentioned in my posts have been endorsed by their manufacturer.

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    • #3
      It's what I'll put in "next time" for heating (don't need AC). So much more efficient in winter than an air heat pump in my location.
      Last edited by lakeside53; 01-14-2014, 01:56 PM.

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      • #4
        There going in around my house, two well systems, one trench all three are over joyed but would not give before and after numbers.

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        • #5
          Originally posted by outlawspeeder View Post
          There going in around my house, two well systems, one trench all three are over joyed but would not give before and after numbers.
          On most geothermal systems the water loop is a closed circuit. In this area (Iowa) you need 1 200 ft deep well for each 12,000 Btu's. More is better, and if you have rocky soil or water saturated soil your wells will vary. With a closed water loop system your pump size will be much smaller than the pump and dump system Winchman had.
          I have worked on systems with a closed loop(s) in a pond or lake. The new geothermal with the compressor and unit in the house are very reliable if properly installed.

          Make sure your installer and engineer have done geothermal before.... and successfully. Your propane or fuel oil guy is going to be really mad at you!


          '"I will be waiting your response - also do you think the 2nd water tank to preheat the house hot water in the summer really is that big of a savings for the additional costs?"
          It depends on how much hot water you plan on using, the second tank is just a storage tank and you will more than likely still need a small gas water heater anyway for backup.
          Last edited by wmgeorge; 01-14-2014, 04:15 PM.
          Retired - Journeyman Refrigeration Pipefitter - Master Electrician - Fine Line Automation CNC 4x4 Router

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          • #6
            My view on this is you will essentially be making a bet that the price of petroleum based fuels will increase faster than the price of electricity over the next 20-50 years.

            In my case, with electricity in the Spokane area at about $.09 kw/hr, my calculations (always dangerous! ) show that for each btu delivered as heat into the shop (7,000 sq. ft.) I am paying approximately half of what it would cost for the same btu delivered from the propane fired unit heaters that also hang from the ceiling. This is ignoring all upfront installation costs, and with the price of propane at $2.50-$2.60 gal.

            As for the ignored installation costs, they are considerable. 4 trenches @ 1500' each, 8'-10' deep and 6,000 feet of 1-1/2 plastic pipe add up to about $14,000.00-$16,000.00 dollars, and this is doing most of the labor myself and does not include costs of any of the heat pumps themselves.

            In hindsight, the system is significantly overkill, but I am ok with that. The past 2 winters have only had 2 of the 4 loops running as only 2 of the heat pump units that I built/modified have been operable. We had some 0؛-5؛ degree weather this winter for 4-5 days and those 2 units had a hard time maintaining 60؛ in the shop. So I need to make at least 1 more unit operable and maybe with the experience gained on the first ones, I will be able to increase efficiency to the point where I can use the 4th loop to do heating and AC in the house.

            I had gotten bids for installation of systems that ranged from $20,000.00-$35,000.00 and I don't think any of those systems would have been nearly as robust as the one I designed. I did use different criteria though. Most heat pump installations of this type are viewed as requiring some type of backup heat source for 1-3 weeks of really cold weather, where I wanted to use the heat pumps exclusively 364 days a year.

            I am guessing that a conventional propane system of this size could cost about $10,000.00, so how much heat for how many years could I have bought for the remaining $10,000.00-$25,000.00? Before the heat pump system existed, it wasn't unheard of to spend $4,000.00-$5,000.00 annually for propane.

            Now these numbers are only a rough accounting as they leave out a number of factors like maintainence, available land area, etc. but I think the general ideas are accurate.

            All that being said, I am very happy that I went the geothermal route, if for no other reason than I learned a thing or two along the way.

            Dave

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            • #7
              Its better to size the system for your average heating load, not for those 1 week or so outside temperatures below design. Oversizing costs more money for the loops and equipment that is just setting there doing nothing 95% of the time. A average geothermal sized and installed correctly has payback over propane and especially fuel oil over 4 to 6 years. Natural gas takes a little longer to get your money back.
              I used to have the calculations on a PowerPoint presentation when I was teaching it instead of running service calls. You can find them all now on the Internet, with a Google search.
              Retired - Journeyman Refrigeration Pipefitter - Master Electrician - Fine Line Automation CNC 4x4 Router

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              • #8
                Neighbors installed "geothermal".... which is more properly called a "ground source heat pump".

                They now have almost no concern for the cost of cooling or heating...... it's so cheap.

                Remember, it is NOT ELECTRIC HEAT..... heat pumps or A/C just "move heat around", they don't have to "make" heat.

                In summer, traditional A/C has to try to reject heat into a hot environment, and in winter a heat pump has to try to pull it out of a cold environment. Both are hard to do, and it takes quite a bit of energy to do it, especially the heating part, if it's colder out than maybe 45or 50 F.

                The "ground source" system rejects heat into the 50F (typical temp) earth, and likewise pulls heat OUT of the 50F earth. MUCH easier and cheaper to do that than to reject it into 105F air, or try to pull it out of 20F air....
                1601

                Keep eye on ball.
                Hashim Khan

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                • #9
                  If you're used to forced air heat, switching to heat pump (air or ground source) can be a bit of a disappointment until you get used to it. The air coming out the vents is only slightly warmer than ambient, so it "feels" cold and drafty.

                  It's more of a warmer than a heater.

                  Not saying heat pumps are bad, just be aware of this aspect when deciding.

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                  • #10
                    I had a heat pump installed about 6 years ago. Really pleased with it.
                    It is a 2.2kW unit that replaced an ancient 10kW oil fired boiler.
                    As others have said they are a low input system, so it is really important to have a very well insulated house to get the full benefit.
                    We have been improving the insulation in our 1960's house since the heat pump was installed and the benefits are obvious. We also supplement the heat with a wood burning stove in the winter.
                    Ours was a retrofit and the installation was very expensive. We have a closed loop groundloop and it heats the room via conventional radiators.
                    Radiators are not the most efficient way of operation, underfloor heating is better, but that was one step too far. You don't see much forced air heating in the UK.
                    One of the less obvious benefits is that the system in maintenance free, with no annual servicing to pay for.
                    In the UK heating oil prices have rocketed in the last 5+ years, electric has gone up as well, so it was a good move.

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                    • #11
                      Originally posted by Stuart Br View Post
                      We have a closed loop ground loop and it heats the room via conventional radiators......the system in maintenance free, with no annual servicing to pay for.
                      ????? I have an air source heat pump running conventional radiators. How do you get away with maintenance free??????

                      Phil

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                      • #12
                        Originally posted by phil burman View Post
                        ????? I have an air source heat pump running conventional radiators. How do you get away with maintenance free??????

                        Phil
                        Phil, no routine maintenance required on the heat pump at all. To be fair we did have a 3 way valve fail under warranty in the heat pump, which I believe was down to poor component selection. Certainly very different to the annual service required on the oil fired system it replaced.

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                        • #13
                          Originally posted by Stuart Br View Post
                          Phil, no routine maintenance required on the heat pump at all..
                          Hi Stuart, is this as recommended by the manufacturer or is it you working on the principle of fix it when it fails (not meant as a criticism). I'm interested as my yearly maintenance cost is/will be £140 if I elect to take it.

                          Phil

                          PS: I had 3 separate three way valve failures on mine. Daikin?????
                          Last edited by phil burman; 01-15-2014, 07:21 AM.

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                          • #14
                            Originally posted by phil burman View Post
                            Hi Stuart, is this as recommended by the manufacturer or is it you working on the principle of fix it when it fails (not meant as a criticism). I'm interested as my yearly maintenance cost is/will be £140 if I elect to take it.

                            Phil

                            PS: I had 3 separate three way valve failures on mine. Daikin?????
                            I have an IVT pump and no regular maintenance is recommended by the manufacturer, other than an occasional clean of the strainer on the radiator circuit. The original 3 way valve was a plunger type (Italian manufacturer) This was replaced by a rotary action one as the supplier believed that these were more reliable.

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                            • #15
                              Originally posted by tylernt View Post
                              If you're used to forced air heat, switching to heat pump (air or ground source) can be a bit of a disappointment until you get used to it. The air coming out the vents is only slightly warmer than ambient, so it "feels" cold and drafty.

                              It's more of a warmer than a heater.

                              Not saying heat pumps are bad, just be aware of this aspect when deciding.
                              I can't agree at all.....

                              This is not a heat pump issue, it is an issue with many new high efficiency furnaces as well. My in-laws have a high efficiency furnace, and they have the exact same situation. A stream of high velocity air at nearly room temp makes some areas feel very cold and drafty.

                              It is likely to be more of an issue with how the system is set up than with the heating method directly. There shouldn't ideally BE streams of high velocity air. That's more-or-less a leftover from old fashioned systems which blew hot air into the cold rooms.

                              We have radiators, which are far superior in creating a warm space. They are not without problems, but they tend to avoid the "draft" issue as well as keeping a more constant temperature without having to blow air around in the house.

                              While it should be "possible" to do a heat pump with radiators, nobody that I am aware of sells such systems.
                              1601

                              Keep eye on ball.
                              Hashim Khan

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