Ground source heat pump systems, GSHPs, are becoming the preferred way to electrically heat and cool a house, an apartment building, or a university campus, or a medical center, etc. This is especially the case in northern European countries, such as The Netherlands, Denmark, Germany, Norway and Sweden. See Appendix.


The big plus for nearby people (and flora and fauna, and forests), due to not burning trees and fossil fuels, will be no additional:

-  Carbon dioxide, CO2, nitrogen oxides, NOx, and carbon monoxide, CO.

-  Sub-micron toxic particulate matter, which deeply penetrates into lungs and other organs, causing respiratory diseases, such as asthma, emphysema, bronchitis.

- Volatile organic carbons, VOCs, and polycyclic aromatic hydrocarbons, PAHs, which cause cancer, and DNA changes in a human fetus.

- See URLs.

Various Types of GSHP Systems


Various types of GSHP systems are in use. However, almost all GSHP systems are closed loop with bore holes and U-tubes.


Closed loop systems are preferred, because they do not affect the groundwater, and avoid the problem of scaling and iron deposition, which would cause problems, in case of open loop systems.


Closed loop can be vertical U-tubes in boreholes. They take up minimal land area.

There are no variations of soil temperatures during the year. See Note.


Closed loop can be horizontal tubing, buried about 8 ft deep in New England, to minimize seasonal variations of soil temperatures.

They take up large areas and require extensive excavation.


Closed loop systems can include:


1) Vertical bore holes with grout and usually one U-tube.

2) Horizontal trenches with coiled tubes, or tubes laid parallel to each other.

3) A nearby pond, at least 8 ft deep in New England, in which are placed coiled tubes.


Open loop systems can include:


1) Vertical boreholes with ground water and a suspended pump; the return line of the loop discharges just below the water level in the bore hole. Such systems are less costly, but may cause scaling and iron deposition problems, etc.


2) A nearby pond, at least 8 ft deep in New England, in which a pipe takes water directly from the pond. The water is returned to the pond after it has circulated through the heat pump. Such systems are less costly, but may cause debris, plus scaling and iron deposition problems, etc.


This URL has detailed descriptions of various GSHP systems



GSHPs provide a near constant output, Btu/h, throughout the year, because the soil temperature remains near constant.

ASHPs (air source heat pumps, also called mini-splits, or cold climate heat pumps), provide decreasing outputs, as the outdoor temperature decreases from 47F to -10F. See URL table 3.


Energy Audit


An energy-efficient house will reduce the capacity and installed cost of any new GSHP system. It will reduce monthly electric bills, and will greatly improve the comfort of the house throughout the year.


Before designing and installing any GSHP systems, an energy audit, including a blower door test, should be performed. The auditor typically recommends improvements and makes estimates of capital costs, obtainable cash subsidies, and annual energy savings from these improvements. Basic improvements include adding insulation and reducing air infiltration by means of sealing.


Such an audit may save a significant percentage of annual operating costs, even without a GSHP system, plus it would reduce the capital cost of any GSHP system, because its capacity, Btu/h, would be less, due to the reduced peak heating demand.


Blower Door Test


A well-insulated/well-sealed house, tested with a blower door at 1.5 whole-house air changes per hour, ACH, at 50 pascal negative pressure, would have average natural ventilation of about 0.15 ACH, much less than the recommended minimum of 0.5 ACH. *


However, that is not relevant, because the house would have an HVAC system, with supply and return ductwork to each room, to supply a minimum of 0.5 ACH to the house for health reasons.

The house would have with an air-to-air heat exchanger to transfer the Btus of the stale exhaust air to fresh incoming air.

Available models have 85% efficiency, i.e., very few Btus are lost.

The house could have a HEPA filter to filter the fresh incoming air.


* The fan of the blower door sucks air out of the house (doors, windows, etc., closed) to create a negative pressure of 50 pascal. After that is achieved, a smoke wand is used to detect the various leaks to be sealed.

One pascal = 0.2 inches of water column; 50 pascal x 0.2 = 10 inches of water column.


Residential GSHP systems:


- Have an installed cost of about $20,000 to $25,000, including 1) ground loop; 2) building hot water (space heating) system; 3) cold air (space cooling) system, and 4) domestic hot water storage system, for recently-built (last 10 years), well-sealed/well-insulated houses of 2000 sq ft, heating demand about 40,000 Btu/h, cooling demand about 20,000 Btu/h.


This capital cost is about 40% to 50% more than the cost of a conventional heating/cooling and domestic hot water system.

However, the GSHPs can reduce utility bills by 40% to 60% compared to equivalent conventional systems.

The extra capital cost is offset by increased operating savings within about 5 to 7 years.


- Have heat outputs, Btu/h, that increase as it gets colder, whereas the heat output of air source heat pump systems, ASHPs, decrease as it gets colder. That decrease is occurring at the same time the house is requiring more heat!


As a result, ASHPs require supplementary heating systems (propane, gas, fuel oil, wood-burning appliances, and electric heaters) during colder days, but GSHPs do not require supplementary systems.

In case of an electricity outage, a propane generator would power the GSHP and the rest of the house.


- Operate efficiently on colder days (coefficient of performance, COP, of about 3), whereas ASHPs inefficiently operate on colder days (COP of about 1.2, or even less). That low, inefficient COP, and associated low heat output, Btu/h, occur at exactly the same time the house is requiring more heat! The electric meter will be spinning!


- Do not have electricity-wasting defrost cycles, whereas ASHPs have defrost cycles that start at about 32F, and increase in frequency and duration, up to 15 minutes, with colder outdoor temperatures.

About 11 to 13% of all annual electricity to an ASHP is for defrost and standby.

No heat is delivered to the house during defrost. See URLs.

See videos in URL


Operation of GSHP System


The below image represents the heat flow diagram of a GSHP system.

The ground loop warms the cold refrigerant gas, which is compressed by the compressor.

The heat of compression is taken away by the building loop.

One pump serves the ground loop, another serves the building loop.

The pumps and compressor draw electricity, plus other items draw electricity.

It is best for the GSHP system to have its own electric meter, for proper accounting purposes.


Thermo-Dynamic Cycle: The Pressure-Enthalpy diagram shows the thermo-dynamic cycle of the GSHP system.

During heating “Heat in” is from the ground and “Heat out” is to the building.


The expansion valve inlet pressure is P-high at T-hot, and outlet pressure is P-low at T-cold.

The refrigerant mixtures in the evaporator and condenser are part fluid droplets and part vapor.


The compressor inlet must have 100% vapor, as tiny droplets would damage the compressor.

The inlet pressure is P-low at T-cold, and outlet pressure is P-high and T-hot.



In heating mode, heat is extracted from the ground, which is transferred to transform the cold refrigerant liquid/vapor mixture to 100% vapor in the evaporator.

The refrigerant typically is R22, R134a or R410a; all are scheduled to be phased out in future years.


The vapor is compressed from T-cold at compressor inlet to T-hot at compressor outlet.

The superheated vapor can supplement domestic hot water, DHW, at about 125F, by means of a desuperheater.

The DHW piping must be insulated to ensure minimal heat loss before the DHW arrives at faucets, etc.

The hot, compressed vapor, about 130F, releases heat as it a condensed to 100% liquid in the condenser.

That heat is distributed (as warm air or hot water) throughout the house.

The compressed liquid refrigerant at T-hot enters the expansion valve, which reduces its temperature to T-cold.

A part of the liquid becomes a cold vapor, the rest becomes cold liquid droplets.

The low-pressure refrigerant mixture enters the evaporator at about 40F, where it absorbs heat from the 50F ground loop to become 100% vapor.


Space Heating with Hot Water: The refrigerant mixture in the condenser needs to be at saturation temperature of 130F, which occurs at 298 psi (compressor outlet) for the R-22 refrigerant. See chart.


Hot water returning from the house at about 90F will be heated by the condenser to about 115F, and circulated around radiators of the house. See Note.


The compressed liquid refrigerant, 298 psi, enters the expansion valve, which reduces the temperature to about 40F, which occurs at 69 psi for the R-22 refrigerant. See chart.


Heat is transferred from the about 50F ground loop to the 40F evaporator, which contains the liquid/vapor mixture from the expansion valve. The heat causes any refrigerant liquid to become 100% vapor, ready for compression, etc.

The ground loop temperature leaving the evaporator would be about 45F.



The house should be well-insulated/well-sealed to allow heating with 115F water.

The hot water piping must be insulated to ensure minimal heat loss before arriving at radiators.

The radiators should be sized to heat the house with 115F water.

Hot water at 100F may be used for houses with tubing embedded in floors.


Space Cooling with Cool Air: The flows through the condenser and evaporator are reversed by means of a 4-way valve. The condenser becomes the evaporator and draws heat from the building, and the evaporator becomes the condenser and rejects heat to the ground.


The refrigerant mixture in the evaporator needs to be at saturation temperature of about 40F, which occurs at 69 psi for the R-22 refrigerant.


Warm air, 70F, passes over the 40F coil and leaves at about 50F. The heat gained from the air causes all the refrigerant liquid in the coil to evaporate, ready for compression to about 65F, which occurs at 111 psi for the R-22 refrigerant. See chart.


Heat is transferred from the 40F evaporator to the 50F ground loop, which would be leaving the evaporator at about 55F.


NOTE: The compressor works much less in cooling mode, 69 psi to 111 psi, than in heating mode, 69 psi to 298 psi.


Domestic Hot Water: A part of the DHW could be produced by de-superheating the compressed 130F refrigerant vapor (upper left corner of Pressure-Enthalpy diagram). The compressor would need to operate at 298 psi to produce 130F water during the summer and most of spring and fall. That would be a significant waste of electricity.


A better approach would be an electric DHW heater with a 50-gal tank.

It makes no noise, unlike a unit with a heat pump.

It heats water much faster than a heat pump.

Packaged units are available; any plumber can install it.

DHW would be produced at less annual cost.

The GSHP system could supplement DHW during winter.


Residential Vertical Closed Loop System


This article focusses on closed loop systems, because they represent about 80% of all residential GSHP systems.


Boreholes and U-tubes


Boreholes usually are about 300 to 400 feet deep. Borehole diameters can vary from 5 to 6-inch diameter. Boreholes need to be about 25 ft apart to minimize thermal interference.


A flexible, high-density, poly-ethylene, HDPE, U-tube pipe is fed into each borehole.


Rule of Thumb: On average, about 150 ft of borehole depth (300 ft of U-tube), is required per ton of heat, or 12,000 Btu/h.


NOTE: The pressure rating of a HDPE tube is determined by its diameter ratio (DR), the ratio of the outside diameter divided by the wall thickness. Lower DRs imply greater wall thickness, which creates greater thermal resistance across the tube wall, which is undesirable for heat transfer.


- Common DRs for HDPE tubes are 7, 9, 11, 13.5, 15.5, and 17.5.
- DR-11, or lower, is suggested for buried portions of earth loops.

- DR-11 PE3608 tube has a pressure rating of 160 psi.

- DR-9 PE3608 tube has a pressure rating of 200 psi.


Grouting Bore Holes


Usually the borehole fills with ground water, but its thermal conductivity, k-value, is about 0.34 Btu/h/ft/F, which is much lower than the surrounding rock, i.e., the borehole must be filled with a thermally-enhanced grout that has a high k-value.


A tremie pipe is lowered to the bottom (the U-tube is already in place) to fill the borehole with grout, from bottom to top.


The pipe is withdrawn as the grout is injected. The grout filling may need to be in steps to allow the Step 1 grout column to harden, as hydraulic pressure might otherwise collapse the bottom of the HDPE pipe. Step 2 grouting likely would be a few days later to allow the grout to harden.


A U-type tube can have a 1.25” outer diameter, 1.00” inner diameter, and 0.125” wall thickness, and a working pressure of 152 psi@73F. See URL.


Grout Hydraulic Pressure:


Specific weight of high-density grout, about 150 lb/ft3

Liquid height, 300 ft

144 sq in per ft2


Weight x height = 150 x 300 x 1/144 = 313 psi

Such a high pressure would collapse the bottom of the U-tube.

The borehole must be filled with grout in 2 steps.


K-value of Grout Mixture Should Closely Match Surrounding Rock: High-density grouts, lb/ft3, are preferred, because they have thermal conductivities more closely matching the surrounding rock. The extra cost is more than offset by less deep bore holes, shorter U-tube pipes and less pumping loss. There are many types of dense rocks, etc. The values in table 1 are averages, for comparison purposes. See URL, page 4.


Table 1/Borehole surrounding material

 k (Btu/h/ft/F)

Dense rock


Average rock


Heavy soil (damp)


Heavy soil (dry)



Grouts: Bentonite grout and cement by themselves are low-cost grouts. Their low k-value would severely restrict heat transfer from the surrounding rock, via the grout, to the U-tube. They should not be used and drilling contractors should be told ahead of time not to use them. See tables.


The GeoPro, Inc., website provides the means to select the thermally enhanced grout mix to achieve k-values from 0.45 (el cheapo) to 1.6 Btu/h/ft/F (more costly, but better). See table 2 and URLs.


Table 2/Grout mixtures


Bentonite by itself


Cement by itself




130 - 150 lb/ft3

0.60 - 0.80


20% Bentonite + 40% Quartzite



30% Bentonite + 30% Quartzite

0.70 - 075

Thermally-enhanced grout

60% Quartzite + Flowable fill (cement + flyash + sand)


Grout and additives

Concrete (50% quartz sand); finer sand is better

1.1 - 1.7


0.45 - 1.6


Length of Bore Holes for Adequate Heat Transfer


Ground loops usually have a mixture of 20% ethylene glycol and 80% water circulating through the U-tubes to extract heat from the ground in winter, and dump heat to the ground in summer.


Usually 1 or 2 boreholes are needed for a well-sealed/well-insulated, 2000 sq ft house, with a peak heating demand of about 40,000 Btu/h, in New England.


The ethylene glycol/water mixture flow through the ground loop at 50F = m x Cp x (Tin – Tout) = 9 gal/min x 60 min/h x 8.622 (see note) x 0.907 (see note) x 5 = 21,115 Btu/h. See Note.

Each bore hole: Flow about 4.5 gpm; heat provided about 21,115 Btu/h.


“Rule of thumb”: 150 ft of depth (300 ft of pipe), provides 12000 Btu/h

Required bore hole length (21115 x 2)/12000 x 150 = 528 ft.

Two 300-ft deep bore holes would be adequate.



All values for bore hole length calculations are adjusted for 50F. See URLs.


Cp of ethylene glycol/water mixture, 20%/80%, is 0.901 at 30F and 0.916 at 80F

By interpolation, is 20/50 x 0.015 = 0.006, i.e., Cp = 0.901 + 0.006 = 0.907 at 50F


Density of ethylene glycol/water mixture, 20%/80%, is 64.7 at 30F and 64.2 at 80F

By interpolation, is 20/50 x 0.5 = 0.2, i.e., density is 64.7 – 0.2 = 64.50 lb/ft3 at 50F


Water density at 50F is 8.3425 lb/gal, or 7.4805 gal/ft3 x 8.3425 = 62.406 lb/ft3


Density of ethylene glycol/water mixture, 20%/80%, is 64.50/62.406 x 8.3425 lb/gal = 8.622 lb/gal at 50F 


Some additional information on bore holes


See closed loop system video.


Bore Hole Heat transfer


Heat transfer to and from the soil depends on the geological make-up of the various layers of material surrounding the bore holes.


- Soil thermal conductivity, k, is the resistance to heat transfer, Btu/h/ft/F

- Soil thermal diffusivity, a = k/(density x Cp). The units are ft2/s. A measure of ground thermal conduction in relation to thermal capacity.

- Soil volumetric heat capacity is the quantity of heat per unit volume, Btu/ft3


- HDPE tubing has high resistance to heat transfer, low k-values of about 0.243 - 0.295 Btu/h/ft/F, much less than thermally enhanced grout mixtures and the surrounding soil. A thin U-tube wall thickness is desired, but not too thin, as it would collapse during grouting.


- Thermally enhanced grout mixtures have high k-values.


For large jobs, computer programs are used to calculate the total length of bore hole required to meet the heating demand of the buildings. A university campus, may require several hundred to several thousand bore holes, each 300 to 400 ft deep.


For small jobs, such as a house, “rule of thumb” is about 150 ft of borehole depth (300 ft of U-tube) is required per ton of heat, or 12,000 Btu/h.


A 2000 sq ft, highly sealed/highly insulated, HS/HI, house, has a heating demand of about 17,000 Btu/h, in New England, during a cold day. Bore hole length 150 x 17000/12000 = 213 ft. One 250-ft deep bore hole would be adequate.


A 2000 sq ft, code house, last 20 years, has a heating demand of about 40,000 Btu/h. It would require 150 x 40000/12000 = 500 ft of bore hole, i.e., two 275-ft deep boreholes would be required.


Lesson: Good things happen to those who insulate and seal! See Appendix.


GSHP System Capacities and Parameters


The GSHP system delivers 40,000 Btu/h to a 2000 sq ft house on a cold day in New England.

The variable-speed compressor draws 40000 Btu/h/{(3412 Btu/h)/kW x 3.5, COP} = 3.35 kW; DC motor rating 3.5 kW

A 40,000/12000 = 3.33-ton system would require two 300-ft boreholes connected in parallel.


Efficiency of system = (Power out, 40000 Btu/h)/(Power in; ground loop + compressor + building circulation + controls, misc.)

A kWh meter should be installed to monitor/display the power to various parts of the system.


Seasonal Energy Efficiency Rating: The SEER- value is a rating of AC units, refrigerators and heat pumps.


Cooling: The SEER rating of a unit is the cooling output during a typical cooling-season divided by the total electric energy input during the same period, say 1000 equivalent full load hours, EFLH.


SEER is calculated with the same indoor temperature, say 65F, over a range of outside temperatures from 65F to 105F, with a certain specified percentage of time in each of 8 bins spanning 5F.


The first bin would be 65 to 70F, say 67.5F, for 1000/8 = 125 hours. Sufficient cooling air would be supplied at 50F, to maintain indoor at 65F, with outdoor at 67.5F.

The second bin would be 70 to 75F, say 72.5, for 125 hours. Sufficient cooling air would be supplied at 50F, to maintain indoor at 65F, with outdoor at 72.5F, etc.


Assume a 5000 Btu/h AC unit; SEER = 10 Btu/h of cooling/W; 1000 EFLH.

The annual cooling output would be: 5000 Btu/h × 1000 h/y = 5,000,000 Btu/y

The annual electricity consumption would: (5,000,000 Btu/y)/(10 Btu/h/W) = 500 kWh/y

Average power draw = (Btu/h)/(SEER) = 5000/10 = 500 W

Hourly operating cost: 0.5 kW x 20 c/kWh = 10 c/h, at a 20 c/kWh household electric rate.



GSHP Systems at Progressive Universities in the US: Here are some URLs of ongoing ground source heat pump projects at universities. No wood chips required.


Ball State University: Its GSHP heating and cooling system, one of the largest in the world, has been fully operational since 2015. See URLs.



GSHP Systems in Northern Europe


These articles have a ton of information for heating and cooling and hot water ALL SORTS of buildings using GSHP systems. Those GSHP systems were installed over a period of at least THIRTY YEARS.




The extensive use of ground source heat pumps (GSHP) nationwide has made Sweden the European leader in geothermal energy utilization, in terms of installed units and capacity, as well as extracted thermal energy (Antics et al. 2013). Approximately one fifth of all single-family houses in Sweden are heated by a GSHP.


Geothermal energy utilization started in Sweden in the 1970’s and 1980’s, triggered by the oil crises, and the following nationwide efforts towards an oil-independent energy system. Heat pump technology was promoted, favored by the national power production strategy based on nuclear and hydropower. Ground source heat pump technology developed rapidly during the 1990’s, and continuous improvement of heat pump COP today allows for rates around 4 - 5 for low temperature heated buildings.


Shallow Well and Coiled Loop Systems: There are around two million single-family houses in Sweden, and approximately 20% - 25% of these houses are heated with GSHPs with shallow wells up to about 600 ft deep or coiled loops buried 6 to 8 ft below grade (2015 status). They work great no matter the outside temperature, because the ground temperature always is about 50F, when outside it is about 0F, or less.


Deep Well Systems: As for deep geothermal energy, several thousand feet deep, exploitation in Sweden remains minimal. Only one plant, taken into operation in the 1980’s, is currently in operation in the very south of Sweden.


This URL provides the 2015 status.


The Netherlands


These URLs provide an overview of GSHP systems for all sorts of buildings in the Netherlands


Anecdote: My cousin lives on the ninth floor of a modern, highly sealed, highly insulated, 12-story, condo building in Maassluis, the Netherlands. The building is part of a residential housing complex of 20 buildings entirely provided with heating, cooling and domestic hot water with GSHP systems already for more than 35 years.


The coils of some of the systems are under the parking lots, other systems have deep wells. After parking your car, click a fob and the lobby lights go on and the elevator door opens, get on the elevator and, without pressing any buttons, it takes you to the ninth floor (smart fob/smart elevator). Press another fob, the front door unlocks and pre-programmed lights turn on. Sturdy blinds are on the outside of the windows and automatically close to reduce solar heat loads in summer and open to increase solar heat gain in winter; the blind’s segments can be pre-set to be partially apart to admit light. That modernity was built-in 35 years ago!!


Per condo rules:

All appliances and lighting are required to be highly efficient.

Showers are required to be low-flow; faucets automatically turn off and on, as in an airport.


In the Netherlands, Sweden, Denmark, etc., near-zero energy buildings and GSHP systems are old hat, routine BAU.



Dartmouth’s 2007 GSHP System for Fahey and McLane Residence Halls


Dartmouth put in a GSHP system covering 100% of cooling demand, but only 25% of heating demand.


Complete GSHP system design calculations for actual systems are available on the internet and “how-to” texts. They take into account the results of test wells to determine soil heat transfer characteristics, which determine the wells and depth and spacing to amply cover the winter heating demand of the buildings. 


The buildings should have been highly sealed and highly insulated to reduce winter heating demand, Btu/h, and that heating demand should be calculated, using standard computer programs, and or tested, using standard methods, BEFORE drilling any wells.


Reducing the heating demand closer to the cooling demand reduces system capacity (less wells, etc.) and provides better utilization of equipment due to longer building time constants, i.e., increased building thermal inertia. Hot water and chilled water storage tanks allow for more hours of steady operation of the GSHP system throughout the year.



Performance Testing of Large Capacity GSHP systems

Below is a list of required measurements to determine the performance of the system:


Total system power and consumption, kW and kWh

Ground loop: Temperature, pressure and flow in an out, power to pump, kW and kWh

House loop, if air distribution system: Temperature, pressure and flow in and out, power to system, kW and kWh

House loop, if hot water distribution system: Temperature, pressure and flow in and out, power to system, kW and kWh.

Compressor: Temperature and pressure in and out, and power to compressor, kW and kWh


Modern systems would have wireless transmitters to an iPad/iPhone for display of the readings and control of the system.


The system efficiency would be:


Heating: (Heat to building, as Btu) / (Total electricity consumption, as Btu)

Cooling: (Cooling to building, as Btu) / (Total electricity consumption, as Btu)


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Comment by Willem Post on January 4, 2020 at 11:12am


The bureaucracy rules the state for ever.

Nothing gets down without the bureaucracy.

Governor Page, a Republican, vetoed a lot of their idiocies; too bad he is cooling his heels in Florida.

Mills, a Socialist Democrat who knows NOTHING about energy systems, often spouts the nonsense she is being fed as if there is no tomorrow.

Comment by Paul Ackerman on January 4, 2020 at 10:45am

so does the "agenda" of EM change with the party in power in Augusta? Or is it more of a bureaucracy that operates its own agenda in defiance of taxpayers?

Comment by Willem Post on January 4, 2020 at 8:31am

Hi Paul,

Gullible people, with energy hog houses, are hyped into ASHP by various state agencies, including Efficiency Maine.

EM gives free training and information and money to Installers on talking points regarding ASHPs. All of that is on the QT.

Often, their ASHPs come with electric heaters to make at appear the ASHPs are performing at low temperatures. That shows up on electric bills.

My referenced articles show the details.

Unless you have a well-sealed/well-insulated house, with a low heating demand, Btu/h, ASHPs are NOT for you.

That is what the state should be saying to these people, instead of deceiving them with rah, rah nonsense.

Comment by Paul Ackerman on January 4, 2020 at 12:02am

well,nice to know that .. I live in a 200 year old house,insulated in the 1990's (exterior walls all rebuilt to do it--could not afford to do that now) and have heated with wood for 40 of my 49 years here,with a K-1 back up heater fitted in 2000.

The notion of spending 10's of thousands of dollars to put in either of these versions -- whether by adding massive amounts of retrofit insulation/windows.doors etc ,to use an ASHP as an "add-on" heat source, or worse yet ,100's of  thousands to build an entirely new house to this nutty super-tight mode needed to utilize the GSHP technology ,just does not make any sense to me .It makes even less sense to me to think the state or federal taxpayers should be subsidizing this stuff for people who want to spend this mind of money. 

I see houses in Rockland now that have added 2 or 3 ASHP units all around them -- older houses too! So at $750 rebate apiece the homeowner is getting $1500-2250 back from the state on their "investment" of what you are suggesting is an ineffective ASHP technology that won't work well when the temperatures go to zero?  So follow the money,who is promoting this "green pipe-dream"?

Comment by Willem Post on January 3, 2020 at 5:21pm


Table 4 shows about 11.6% of all Vermont free-standing houses are suitable for heating with ASHPs, because they are well-sealed and well-insulated, i.e., they have low heating demands and low infiltration.

Any heating system, ASHP, GSHP, or traditional would have a low capacity, Btu/h.

The GSHP would not need a supplementary heating system, because its output, Btu/h, does not decrease at colder temperatures.

The ASHP would need a supplementary heating system, because its output, Btu/h, does decrease at colder temperatures. Owners would need traditional back-up systems (propane, gas, fuel oil, wood stoves, and electric heaters). 

The ASHP and supplementary, each have their own cost of financing, and cost of service calls and maintenance contracts.


Comment by Willem Post on January 3, 2020 at 4:53am

GSHPs get a 30% federal tax credit.

Drilling in Maine and Vermont is costly.

In that case, horizontal loops need to be used.

GSHPs should be installed when an ENERGY-EFFICIENT house is built to minimize capital cost.

There is NO substitute for having a house that is highly sealed and highly insulated.

Such a house would have a LOW heating demand, Btu/h, on cold days.

Only well-sealed/well-insulated and HS/HI houses are suitable for heating 100% with ASHPs. See Appendix and URLs.

There are plenty of people in Main and Vermont who were cajoled/lured into installing ASHPs in their energy-hog houses.

They were told they would be "green, save the world", etc. 

They found their ASHPs do not put out enough heat on colder days.

They have to turn on their traditional systems and turn off their ASHPs. See URLs.

Now they have TWO systems, each to be financed over a period of years, and each with service calls and service contracts.

NOTE: About 85% of all free-standing houses in Maine and Vermont are energy hog.

Comment by Paul Ackerman on January 2, 2020 at 9:06pm

Interesting,if tedious to go thru,statistics. Essentially meaningless for Maine because drilling wells here (on the coast in particular) to install GSHP systems would be absurdly expensive. Not to mention the unlikely service life of such systems here coming anywhere close to a break even cost against any "fossil-fuel" or wood -fired system.

Costs?  Better sit down. Relatives who installed such a system in Maryland --where it is very easy to drill 200' plus without going through granite or schist -- had costs of around $40K. This system had a major malfunction within the first year,causing thousands in damage to the house.

Just call a well driller and ask for a quote on drilling in your area of Maine to 400 ft as average,calculate the per ft costs and you can adjust the potential for just that factor to impact the overall costs. That would only be a portion of the total costs of such a system.

Comment by Penny Gray on January 2, 2020 at 5:09pm

So, how much would one of these GSHPs cost the average Maine family?


Maine as Third World Country:

CMP Transmission Rate Skyrockets 19.6% Due to Wind Power


Click here to read how the Maine ratepayer has been sold down the river by the Angus King cabal.

Maine Center For Public Interest Reporting – Three Part Series: A CRITICAL LOOK AT MAINE’S WIND ACT


(excerpts) From Part 1 – On Maine’s Wind Law “Once the committee passed the wind energy bill on to the full House and Senate, lawmakers there didn’t even debate it. They passed it unanimously and with no discussion. House Majority Leader Hannah Pingree, a Democrat from North Haven, says legislators probably didn’t know how many turbines would be constructed in Maine if the law’s goals were met." . – Maine Center for Public Interest Reporting, August 2010 Part 2 – On Wind and Oil Yet using wind energy doesn’t lower dependence on imported foreign oil. That’s because the majority of imported oil in Maine is used for heating and transportation. And switching our dependence from foreign oil to Maine-produced electricity isn’t likely to happen very soon, says Bartlett. “Right now, people can’t switch to electric cars and heating – if they did, we’d be in trouble.” So was one of the fundamental premises of the task force false, or at least misleading?" Part 3 – On Wind-Required New Transmission Lines Finally, the building of enormous, high-voltage transmission lines that the regional electricity system operator says are required to move substantial amounts of wind power to markets south of Maine was never even discussed by the task force – an omission that Mills said will come to haunt the state.“If you try to put 2,500 or 3,000 megawatts in northern or eastern Maine – oh, my god, try to build the transmission!” said Mills. “It’s not just the towers, it’s the lines – that’s when I begin to think that the goal is a little farfetched.”

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Sign up today and lend your voice and presence to the steadily rising tide that will soon sweep the scourge of useless and wretched turbines from our beloved Maine countryside. For many of us, our little pieces of paradise have been hard won. Did the carpetbaggers think they could simply steal them from us?

We have the facts on our side. We have the truth on our side. All we need now is YOU.

“First they ignore you, then they laugh at you, then they fight you, then you win.”

 -- Mahatma Gandhi

"It's not whether you get knocked down: it's whether you get up."
Vince Lombardi 

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Hannah Pingree on the Maine expedited wind law

Hannah Pingree - Director of Maine's Office of Innovation and the Future

"Once the committee passed the wind energy bill on to the full House and Senate, lawmakers there didn’t even debate it. They passed it unanimously and with no discussion. House Majority Leader Hannah Pingree, a Democrat from North Haven, says legislators probably didn’t know how many turbines would be constructed in Maine."

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