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  • #16
    If the geothermal only warms to 50 degrees and in winter you use a fireplace or gas to "supplement" to get the interior air to something like 60-65 degrees wouldn't the geothermal now be cooling the air you are trying to heat?

    The only place I can see geothermal being perfect for is the shop.
    Andy

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    • #17
      If they have a stream of room temperature air when the unit is heating something is wrong. I have a Trane 94% furnace and before that a Lennox pulse. Both high efficiency units. On my newer Trane I went with the ECM motor which varies the speed like a VFD on a mill motor. I have it on constant fan 24/7/365 the speed is set for low fire heating mode. IF and when it ever goes to Hi fire the motor ramps up, and of course it goes to Hi speed when on AC and then ramps slowly back down. Off constant fan the motor speed varies as to high or low fire heating and always starts very slow so you don't get that blast of cold air out of the ductwork.

      IF you are going to a geothermal or air source heat pump system the ECM motor is the difference between day and night or in this case comfort or not.
      Retired - Journeyman Refrigeration Pipefitter - Master Electrician

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      • #18
        Geothermal and air source heat pumps discharge air temperatures are anywhere from 90 - 110 degrees. Still warmer than outside air temperatures.
        Retired - Journeyman Refrigeration Pipefitter - Master Electrician

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        • #19
          Originally posted by J Tiers View Post
          <snip>
          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.
          <snip>
          Since you are 'pumping' the heat in summer or winter I would think that the costs are related to the differential temperatures. that is to say what may be the case in Missouri may not be the case in Wisconsin... Regional electrical rates are a variable as is the cost of natural gas. In our area for example, it's at least twice as expensive to operate a water heater with electricity as it is to heat with gas. The electricity is much more efficient, but that does not relate directly to lower operating costs. There are reasons to use one or the other based on recovery rates, venting, water demand and installation costs.

          Originally posted by vpt View Post
          If the geothermal only warms to 50 degrees and in winter you use a fireplace or gas to "supplement" to get the interior air to something like 60-65 degrees wouldn't the geothermal now be cooling the air you are trying to heat?

          The only place I can see geothermal being perfect for is the shop.
          In the case of an air conditioner, the heat source is the interior of the house, In our area the differential temperature is on the order a maximum of 30 degrees in the summer, plus the latent heat in indoor air that is present until the humidity is reduced allowing the indoor temperature to fall to the thermostats' set point.

          In the winter the differential a heat pump see's here is as much as 85 degrees. The heat energy comes from the ground sourced heat loop, I'm no refrigeration guy, but it seems to me it takes a lot more water to supply the BTU's to effect an 85 degree rise as opposed to a 30 degree drop...


          paul
          Last edited by ironmonger; 01-15-2014, 10:34 AM.
          paul
          ARS W9PCS

          Esto Vigilans

          Remember, just because you can doesn't mean you should...
          but you may have to

          Comment


          • #20
            My father heats with a heat pump and has been doing so since the early 90s. He got a little past the 20 years he was told the furnace would last and replaced it last year.

            His house was decently insulated for the 70s, but is pretty leaky by today’s standards. Strong north winds create plenty of drafts; the north side is almost all windows.

            So, to compare against my house: the same size house, in a much windier location, less insulation and old windows, air conditioning that I don’t have, no burning 5 cords of wood like I do, and his utilities are still 10% less than mine. It’s been a cost effective and easy to use system for him, which is why he went with the heat pump again, even though gas is now available on the road.

            His is an open loop design, pulling water from the well. Goes through a ton of water but he’s had no problems over the years and the high use actually helps with the iron problems he had. The water for the hot water heater is supplied from the furnace, which has made a big difference in how much the heater has to work.

            From what I’ve seen, it’s been a very good system and has delivered on all the promises.
            George
            Traverse City, MI

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            • #21
              Originally posted by ironmonger View Post
              Since you are 'pumping' the heat in summer or winter I would think that the costs are related to the differential temperatures. that is to say what may be the case in Missouri may not be the case in Wisconsin... Regional electrical rates are a variable as is the cost of natural gas. In our area for example, it's at least twice as expensive to operate a water heater with electricity as it is to heat with gas. The electricity is much more efficient, but that does not relate directly to lower operating costs. There are reasons to use one or the other based on recovery rates, venting, water demand and installation costs.



              In the case of an air conditioner, the heat source is the interior of the house, In our area the differential temperature is on the order a maximum of 30 degrees in the summer, plus the latent heat in indoor air that is present until the humidity is reduced allowing the indoor temperature to fall to the thermostats' set point.

              In the winter the differential a heat pump see's here is as much as 85 degrees. The heat energy comes from the ground sourced heat loop, I'm no refrigeration guy, but it seems to me it takes a lot more water to supply the BTU's to effect an 85 degree rise as opposed to a 30 degree drop...
              paul
              Air to Air or air source heat pumps really aren't intended or efficient in our areas Paul. Are they installed and do they work? Yes but when it gets say below 15-20 degrees F outside the electric or backup heat may be required. Geothermal heat pumps gather heat or reject heat to the ground loop or water loop. Ground temperature varies from one part of the county (world) to another. But if you figured 50 degrees like in Iowa or Wisconsin you would be pretty close. The COP for a ground source heat pump can be as high as 4:1, or one unit of electricity = 4 units of heat out. Your results may vary, see manufactures ratings for details. Properly sized and installed loops or wells are a must.
              Retired - Journeyman Refrigeration Pipefitter - Master Electrician

              Comment


              • #22
                Originally posted by ironmonger View Post
                Since you are 'pumping' the heat in summer or winter I would think that the costs are related to the differential temperatures. that is to say what may be the case in Missouri may not be the case in Wisconsin... ... it seems to me it takes a lot more water to supply the BTU's to effect an 85 degree rise as opposed to a 30 degree drop...
                For air-source heat pumps, yes, the SEER rating assumes a certain outside temperature, so if it's colder than that, you will NOT see the rated efficiency. And beyond a certain temperature differential, an air-source heat pump requires more electricity to pump heat than pure resistive heat would use. So they usually have "emergency" heat strips that kick on in cold weather (there goes efficiency, but at least you don't freeze). The cut-off temperature depends on the quality of the equipment; older/cheaper ones cut off about 32°F and newer/better ones can pull heat heat of the air down to like 0°F. Though efficiency at 0°F is well below that of 32°F, and when it's that cold, the heat pump must periodically go into air conditioner mode to pump heat into the outdoor coil to defrost it.

                Ground-loops don't have these problems since the dirt stays about 55°F or so, so I consider them superior to air source (if you can afford them and have the room for the loops).

                Originally posted by J Tiers View Post
                I can't agree at all.....

                This is not a heat pump issue, ... My in-laws have a high efficiency furnace, and they have the exact same situation. ... some areas feel very cold and drafty.

                It is likely to be more of an issue with how the system is set up
                Originally posted by wmgeorge View Post
                IF you are going to a geothermal or air source heat pump system the ECM motor is the difference between day and night or in this case comfort or not.
                Good points, both of you. My experience is limited to my parent's 15-year-old single-speed system, which has all of the defects mentioned. Given a proper setup, I agree they could be a lot better.

                Comment


                • #23
                  The defrost cycle really killed me in wet WA. For a great deal of the winter it's between 32 and 40F with high humidity. When I had a heat pump it would often go into a defrost cycle every hour. The 30kw EM heat was on a lot... and the entire system was fed from a 100 amp 240 breaker. We converted to natural gas and I sold off the heat pump. This was in 1992.

                  My neighbors with recent installations have combined air-air heat pumps and gas heat units that switch automatically based on outside temperature and the cost differential of gas and electricity. Their switchover point to natural gas is about 38F (even though the units are rated down to way below freezing). Out where I live AC isn't really used - maybe 1 or two days a year!
                  Last edited by lakeside53; 01-15-2014, 12:41 PM.

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                  • #24
                    Originally posted by wmgeorge View Post
                    Air to Air or air source heat pumps really aren't intended or efficient in our areas Paul. Are they installed and do they work? Yes but when it gets say below 15-20 degrees F outside the electric or backup heat may be required. Geothermal heat pumps gather heat or reject heat to the ground loop or water loop. Ground temperature varies from one part of the county (world) to another. But if you figured 50 degrees like in Iowa or Wisconsin you would be pretty close. The COP for a ground source heat pump can be as high as 4:1, or one unit of electricity = 4 units of heat out. Your results may vary, see manufactures ratings for details. Properly sized and installed loops or wells are a must.
                    Just to be clear.. I wasn't referring to air to air, merely that the differential in summer to winter heat load exists.

                    The geothermal system must still extract many more BTU's from the ground loop in the winter than it injects in the summer.

                    In south eastern Wisconsin we pay about $.14 per kilowatt hour, we pay about $.68 per therm of natural gas.

                    At the approximate rate of 29 kilowatt hours per therm that comes out to $4.06 worth of electricity to $0.68 of natural gas, or about 16% of the cost of electricity. If you get a 4:1 output It seems that around here the heat-pump looses.


                    paul
                    paul
                    ARS W9PCS

                    Esto Vigilans

                    Remember, just because you can doesn't mean you should...
                    but you may have to

                    Comment


                    • #25
                      Originally posted by ironmonger View Post
                      Just to be clear.. I wasn't referring to air to air, merely that the differential in summer to winter heat load exists.

                      The geothermal system must still extract many more BTU's from the ground loop in the winter than it injects in the summer.

                      In south eastern Wisconsin we pay about $.14 per kilowatt hour, we pay about $.68 per therm of natural gas.

                      At the approximate rate of 29 kilowatt hours per therm that comes out to $4.06 worth of electricity to $0.68 of natural gas, or about 16% of the cost of electricity. If you get a 4:1 output It seems that around here the heat-pump looses.

                      paul
                      Paul the calculations are a bit more involved than that, takes into consideration the efficiency of each, but you are close. Don't have the time to get out my old teaching material right now where I have my notes.

                      A 1 HP compressor will transfer 12,000 Btu's of heat either one way or the other. This is at air conditioning suction or evaporator pressures, as the ground gets colder outside toward the end of a normal winter the loop temperature drops and so the suction pressure drops. The compressor becomes less efficient at lower suction pressures.

                      Out in the shop trying to get what looked like an DRO easy install completed.

                      Anyway in all cases the ground source or geothermal heat pump always comes out ahead, unless you are getting a very good electric rate or gas rate. The .68 cents per therm of natural gas looks really low, at least compared to Iowa. Is that factoring in the pipeline and delivery charges they seem to tack on?
                      We pay .08 cents KwH here, the current gas rate factoring all the charges in = .836 cents per Therm.
                      Last edited by wmgeorge; 01-15-2014, 02:18 PM.
                      Retired - Journeyman Refrigeration Pipefitter - Master Electrician

                      Comment


                      • #26
                        Originally posted by wmgeorge View Post
                        Paul the calculations are a bit more involved than that, takes into consideration the efficiency of each, but you are close. Don't have the time to get out my old teaching material right now where I have my notes.

                        A 1 HP compressor will transfer 12,000 Btu's of heat either one way or the other. This is at air conditioning suction or evaporator pressures, as the ground gets colder outside toward the end of a normal winter the loop temperature drops and so the suction pressure drops. The compressor becomes less efficient at lower suction pressures.

                        Out in the shop trying to get what looked like an DRO easy install completed.

                        Anyway in all cases the ground source or geothermal heat pump always comes out ahead, unless you are getting a very good electric rate or gas rate. The .68 cents per therm of natural gas looks really low, at least compared to Iowa. Is that factoring in the pipeline and delivery charges they seem to tack on?
                        We pay .08 cents KwH here, the current gas rate factoring all the charges in = .836 cents per Therm.
                        Our gas is actually $0.611152 per therm plus $.31 per day pipeline charge. For this month that works out to $0.747424242 per therm.

                        With distribution costs thrown in the electricity comes out to $0.152048364 per KWH.

                        I only included the ridiculous places to the right of the decimal point because our utilities do when they calculate our bill...

                        I guess thats why what makes sense in your area sucks here...

                        I just received the last panel components for my EDM sinker project. That's a subject for a future post though...

                        paul
                        paul
                        ARS W9PCS

                        Esto Vigilans

                        Remember, just because you can doesn't mean you should...
                        but you may have to

                        Comment


                        • #27
                          I don't think a heat pump,is suited for many areas of the Country, or climate. Zone 5 or less is iffy in my mind. Otherwise, new refrigerants and compressors/units do quite well, much better than just a few years ago. And I'm not talking about the extreme high SEER units, just relatively normal units.

                          Consider the costs. A normal heat pump in zone 6 and higher do fairly well, even in the winter. They supply decent heated temps down to 15 degrees then the efficiency drops off. Sure they go through defrost cycles, but it's not that big if an issue. So, weigh the cost of a normal installation, and the efficiency temps in a full year. The amount of "not so efficient" days are small, and they aren't even full days. So you use a bit more electricity.

                          Now factor in the ground source system cost. Yes it runs more efficiently in the "bad" times, but how many years will it take to offset the installation costs?

                          If one had the means of doing the work themselves, then fine. But to pay for it all to be done costs a lot.

                          Comment


                          • #28
                            Originally posted by J Tiers View Post
                            While it should be "possible" to do a heat pump with radiators, nobody that I am aware of sells such systems.
                            I have an air heat pump with conventional water filled radiators. (System by Daikin http://www.daikin.co.uk/domestic/nee...rner/index.jsp) The heat pump is two stage and will boost the temperature to 70 deg C + when necessary, which is plenty for radiators. The down side is that the extra boost uses additional energy so not as efficient as the under-floor water circulation type which only needs 35 deg C to be effective.

                            Phil

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                            • #29
                              Originally posted by rws View Post
                              I don't think a heat pump,is suited for many areas of the Country, or climate. Zone 5 or less is iffy in my mind. Otherwise, new refrigerants and compressors/units do quite well, much better than just a few years ago. And I'm not talking about the extreme high SEER units, just relatively normal units.

                              Consider the costs. A normal heat pump in zone 6 and higher do fairly well, even in the winter. They supply decent heated temps down to 15 degrees then the efficiency drops off. Sure they go through defrost cycles, but it's not that big if an issue. So, weigh the cost of a normal installation, and the efficiency temps in a full year. The amount of "not so efficient" days are small, and they aren't even full days. So you use a bit more electricity.

                              Now factor in the ground source system cost. Yes it runs more efficiently in the "bad" times, but how many years will it take to offset the installation costs?

                              If one had the means of doing the work themselves, then fine. But to pay for it all to be done costs a lot.
                              The geothermal unit costs about the same as a quality high efficiency gas furnace and high SEER rated Air Conditioning unit. The cost of the loops or wells (this is a sealed water loop) is the additional expense. The payback between a geothermal over a conventional system varies with the cost of the natural gas/fuel oil/propane fuels it would replace. It will be anywhere between 4-6 years for fuel oil and propane, longer for natural gas perhaps as much as 10 or 12 years.

                              Link to Climatemaster calculator > http://www.climatemaster.com/residen...lator/sc01.php

                              The ground temperature at 5-8 feet does not get colder because of the outside air temperature. I worked on the units in the field and taught the subject and other HVAC related for over 12 years.

                              My very favorite heat pumps are the air to air ones,.... the rooftop units I remember with fond memories Much rather be working on a nice HW boiler.
                              Last edited by wmgeorge; 01-15-2014, 07:37 PM.
                              Retired - Journeyman Refrigeration Pipefitter - Master Electrician

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                              • #30
                                I have a 3 zone Geothermal system heating/cooling a 3800 sq ft colonial in Ct. My electric bill never goes over $350 and that includes all electric use. In my previous 1800 sq ft home, I had oil heat and the electric bill alone was averaging $200. I also have a 50 gallon propane water heater and that averages $70/month. The house uses Icenene foam insulation which I highly recommend. For comparison, my son's house is 10 minutes away and displaces 1000 sq ft. He heats with electric baseboard and his bill runs about $700/mo despite keeping his house about the temperature of Siberia. I have one water well and three geothermal wells that all are just shy of 300ft deep. The GT wells are closed loops with antifreeze running thru them.
                                Last edited by epanzella; 01-15-2014, 10:10 PM.

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