Frequently Asked Questions (FAQ)

Outside the house

Are geothermal horizontal loops appropriate for existing houses as well as new construction?

Yes. You can substitute all or portions of your system with ground heat or cooling.  For existing homes, you may leave old components in place or remove them.  Right now, using the existing air handler and duct system is best.  For homes with baseboard hot water heat, it might be necessary to run some ducts.  I have left my oil burner hooked up, so that if we get a week of zero temperatures that strains my geothermal capacity, the computer automatically switches to fuel oil heat until the geothermal system is ready again.  A new home system I am designing will have a propane backup system, but Caren and Bob's horizontal loop system has worked great for 25 years without backup.

Do I need a professional engineer to layout my horizontal geothermal loop?

No. There are no licensing requirements in Connecticut or New York for the horizontal loop. Where deep soils and acreage are limited, you might choose the more expensive drilled geothermal wells that  must be drilled by licensed well drillers. The advantage of an engineered drawing is that the autocad program used to design the site plans on this web site can accurately determine pipe lengths for ordering and sizing purposes.

What permits do I need?

You need a wetlands permit if you are digging within the upland review area (100' from a watercourse or wetland in Litchfield)  We do not recommend installing horizontal loops in wetlands at this time, except for deep ponds on your own property. The policy now is that you must send in your application and get on the next monthly meeting agenda, even if working only under an existing lawn near a wetland or watercourse.  There have been no adverse impacts associated with wetlands, as long as prudent erosion controls are implemented. Always specify silt fence to protect sediment from entering wetlands until grass seed is germinated. A good rule of thumb is to keep all trenching at least 10' away from wetlands so that the excavator need not go near wetlands. Do not change groundwater flow in the trench that would affect a nearby wetland.

Send to the health dept to show it is not near a septic system. (10' to Primary)

For inside heating and air conditioning work, you need a licensed HVAC person.  There are some provisions for the do it yourselfer.  But you must do the work yourself in a home in which you reside. Check with the Dept. of Consumer Protection at

Who should determine if there are underground utilities under my lawn?

You should - first by making a visual observation of your yard and then by reviewing your survey and your septic system As Built plans on file in the Torrington Area Health District.

CBYD = Call Before You Dig in Connecticut 800-922-4455 must be called a few days before you start.  They can locate your main underground power, but they do not locate all utilities, such as sprinkler systems or even electric outdoor lighting.  4" diameter footing drains if cut, can be spliced, but should normally be on a straight line from the outfall to the corner where they leave the house.

The Health Code requires a 10' separation from a primary septic system. Send Torrington Area Health District the plans to be sure you comply.

There should be no surprises for the backhoe/ ditch witch operator.  Everything should be clearly spray painted before the start.  It is the homeowners responsibility to map out everything that will be encountered underground. Test holes by shovel or machine might be required. If you are not certain, do not dig.

What if I have high ledge or ground water?

High ledge is not good.  If the trench cannot be 4' deep or deeper, you will loose electricity efficiency because the ground will not be warm in the winter.  But short runs where the pipe is only 2' or 3 ' deep do not loose that much efficiency, and are not a reason to terminate the project.

Groundwater is a better conductor than air between soil particles.  So builders will be surprised that good dry sandy soils for foundations and septic systems are less desirable than mottled hardpan with high groundwater that is good for geothermal systems.

Note: I recently learned that high ledge is being used in New York State where contractors are using track drills to drill 70' deep angled holes about 2" in diameter. They are installing copper geo pipe, in areas of limited acreage or access to a well drilling rig.  But in Connecticut, this might be considered unlicensed drilling.

Here's what a  track drill looks like: 

PS Carl notes that the copper in the ground might be for the Freon or Puron Refrigerant within the heat pump, but if so, these are not biodegradable for insertion into the ground like Propylene Glycol. Anyone able to provide more info for this web site on track drilling? Thanks,


We are also looking into farm style trenchers:


What if I encounter a buried stump?

DEP allows burial of stumps that came from the same property as long as the burial hole does not exceed 10 cubic yards.  If the backhoe encounters a stump, rebury it nearby, or dispose of it at Supreme Industries. stumps should not be buried near septic systems or driveways where decomposed settlement could be a problem.

Will the temperature change affect my plants or animals?

No. In the summer, the outlet pipe from your house might rise in temperature like mine this week.  Outdoor temps were up to 95 degrees as you recall if you ran the Litchfield Hills Road Race like I did. My inlet pipe water temperature was up to 65 degrees, and the outlet temperature was as high as 93 degrees.  After the 730 feet through the pipe temperature was back at 65 or 66 degrees.  The pipe easily withstands this heat, and since there are no roots near the pipes, no vegetation is affected.  rodents would no sooner nibble on this warm pipe than they would on your water well pipe line from your well to your house.

In the winter, soil immediately surrounding the geo pipe could freeze near the house if it is put out at say 20 degrees. Again roots and animals would not be affected.  Grass 6' above should not be affected.  As Irma Bombeck use to write -The grass is always greener over the septic tank :}

There have not been reports of moles or mice eating through water well line polyethylene, so the thicker geo pipe should not be something that attracts them either. HDPE means high density polyethylene pipe.  The black geo pipe density appears to meet this definition.  For pond loops where beavers might gnaw on underwater loops, add a protective screen or encase the geo pipe in a perforated sleeve pipe.

Can I split my geothermal loop into two closed loops instead of one?

Yes. See one of the designs that does not cross electric lines, etc. Use a manifold inside to connect to one heat pump or use two heat pumps.

What happens if the loop does break someday?

If the loop breaks, the heat pump will react as pressure falls to zero. Gages are attached to the outside of the heat pump.  At that point, the line should be dug up at mid section and air tested until the break is located.  Then heat fuse a repair line.  But this has never been reported to have happened, and the pipe does have a 50 year lifetime warranty.  For areas where outside connections are necessary, provide manhole type portal boxes for future access.

Remember that the only spillage in a worse case scenario would be water with a propylene glycol (food based) 17% solution that would not harm anything.

Does it matter if I am on a hill?

No. The geo pipe is completely filled with water and biodegradable antifreeze. Frictional head loss is only a function of internal pipe resistance, not head water depth. So no topography info is needed.  Note that this means that well systems and horizontal loop systems can use the same flow controller circulating pump.

The lengths within deep drilled wells and the geo pipe soil or bentonite contact are figured into the rule of thumb trench length or well depth calculations that can also be determined by various computer programs.

How long does it take to order and receive the geo pipe?

Allow two weeks. So if no wetlands meeting is required, and you know the exact length, plan on digging in two weeks. And Call Before You Dig one week in advance.

How much pipe do I need, and what size?

All those googled web links give rules of thumb like 200' to 300' per ton depending on soils and pipe volumes.

After struggling with the heavy 2" diameter pipe, I am an advocate for 1 1/2" pipe. But choices must be made depending on amount of soil that can be utilized, type of excavating equipment available, laborers that cannot enter deep trenches, etc.  Some web sites warn against putting too much pipe into too little a trench length, so I do not favor the slinky coil method, but okay where soil resources are limited.  Try to get the most out of the soil with enough pipe that is not excessively long for your wall mounted circulating pump.

Remember we are only drawing out enough heat to help a single family dwelling here.  For geothermal heating of industrial or large facilities, or for electric power generation, you need several deep wells or a "Geo thermal hot spring" as found elsewhere in the USA.

The purpose of your geothermal system is to save energy and money.  Over sizing can make the system so expensive that a decision is made not to go forward.  We need not have a Cadillac system to anticipate the rare peak needs.  On very cold days, simply plug in an electric space heater, or feed the fireplace.

Is it worth it to spend an extra $5000 in unneeded loop pipe so that you save $5.00 or $10.00 on your CL&P bill occasionally? No.

Why did you prepare this web site?

I think it is noble to share information rather than to try and profit from it, at people's expense.  I was able to get free information thanks to Google, and I feel that my 30 years of professional engineering experience in soils and water allow me to make some reasonable recommendations.  Do I accept liability for any of this? No. But I can help you if you need it, and I can rest easy knowing that the American spirit for energy independence is alive and well thanks to web sites like this, and energy pioneers who are willing to install a horizontal loop system.


Please email me your further questions for posting with or without your name.

I have been taking on a few selected clients who reimburse me for my time, but this web site encourages the Do it yourselfer, not the paying client.

Inside the house

Can I hook up a heat pump for all or part of my house?

Yes. I substituted a 2 1/2 ton heat pump for one of my 2 1/2 ton electric supplied air cooled air conditioners. Generally you should match the tonnage or BTU capacity that exists.  My 4000 square foot house uses 5 tons total, but my acreage was only conducive to 2 1/2 tons or half of my heating needs.

Can the heat pump be hooked up to baseboard ducts or radiators?

Ducts yes. We are looking into retrofitting baseboard heat . The 140 degree furnace temperatures might be less, and the lineal feet of radiator must be determined.  It also depends on how well insulated your house is for the heat expected from radiators.  In one project, we are considering adding an air handler and ducts to the existing radiator system.  Radiant floor heat is also feasible, but more costly.

Here are some articles that show the limits of hooking up to baseboard radiators:


EERE Consumer's Guide: Limitations When Replacing Existing Heating Systems


Can the heat pump be used to supply hot water?

Yes. The drilled well systems routinely do, and horizontal loops with enough BTU rating can handle hot water lops too.  In one house, an $11,000 heat pump replacement unit handles everything.

For the Carrier Heat pump I had installed in my home, there is an optional add on for hot water coils.  If I draw adequate heat this winter, I will consider adding hot water next year.

Is the heat different inside the rooms?

Someone told me he didn't like geothermal because he said it feels like when you get out of a swimming pool, and the air temperature might be 70 degrees, but water evaporation makes you feel cooler. Since more air circulates at 100 degree coil temperature than140 degree fuel oil coil temperature, there might be a difference in humidity. But families who have lived with geothermal systems for years said this is not true.

Can the heat pump be placed inside or outside my house?

Yes. I prefer inside, and mine is quite quiet on its dampening pad.  The basement is a perfect spot for a heat pump.  The Products brochure that comes with the heat pump notes that there is minimal maintenance. Mostly clean the filter on your existing air handler like you normally do.

May I have a heat pump that does not do air conditioning?

Yes. The hybrid that does both with a 20 minute resetting cycle is more expensive than a heat only heat pump.

Can I place a heat pump in my attic?

I wouldn't. If you can get it through the opening and you insulate the geo pipe leading to it I suppose its feasible, but be sure the ceiling beams can support the load, and dampen the sound.

Is it true that someone with a horizontal geothermal loop air conditions his three bay garage?

Yes because he said "Why not? It's free!" He claims that the geo AC works even better than the heat.

But it does use electricity, and short of meters on every heat pump, this cost is unknown.


How much power does the heat pump use compared to the electric air conditioner?

The electrician installed two watt meters near the panel box, so we can read how much power is drawn by the heat pump and flow pump versus the electric air conditioner.


Here are the readings for the heat pump. I need an expert to interpret, but it says 1300 watts are being used.

This is like eleven 120 watt light bulbs. It says that is for 125 volts, although voltage is 230.

The electrician read amperage on the wire at about 9 amps. This would mean 155 volts.


Anyway, the electric air conditioner also drew 1300 watts in 75 outside degree temperature.

I am waiting to see if more wattage is used by the electric air conditioner when outside temperature goes to 90 degrees.

These initial readings do not match with the Coefficient of Performance standard of 3 or 4 expected.

Heat efficiency is different, but I am disappointed in the apparent lack of AC savings.

And it was discouraging to learn that Connecticut Light and Power is raising rates 6%!

More as data becomes available.

But although electric savings on cooling is not a homerun, I heard at the 4th of July Picnic that some oil dealers are now offering lock in prices for next winter:


With Oil at $48 per barrel (today on Dec 2) or 1/3 of what it was this summer, people are not so interested in saving fuel oil, but let's see if that price holds, and the 500 gallons per year I am not smoking up my chimney should be helping air quality.



Note: I have our CL&P bill for the month of August.  $155 (With 6% increase) for keeping all 4000 sq foot cool and powered while we were here full time.  Wattage may be high, and the month was not that warm, but this is the lowest bill we ever had.  Pumping the heat back under the lawn seems to be saving us electric costs.

The Coefficient of Performance is thus at 4.0 or so because although it uses the same wattage, it does not seem to run as long.


At the November lecture, I noted that the COP of 4 means I am using 1/4 the electricity to heat that an electric heat customer would use. This is like a big Ford pickup truck that was getting 15 miles to the gallon suddenly getting 60 miles to the gallon without reducing the steel weight or design performance of the truck!!


Continuing with my CL&P bills,

$140 for  September, about $100 less than last year.

And for the cold November, my bill was $178 including the new 6% for green energy. (12% higher than comparable last year)

I used 29 KW compared to 23 Kw last November.  So heating 2000 sq. ft for a month is costing me

29-23 = 6 KW or 25% of $178 = $45 with the increased rates and 6% extra I signed up for this year.


So our house is toasty warm this winter. 

But neighbors please, when it gets real cold, you don't have to open your windows!!   


Pete 9/5/08 rev 12/02/08


Email inquiries:

First, thanks for sharing your information, I would love to stop buying fuel oil.

 Four questions if I may, first, you mention in one of your FAQs that the system is meant to “help” heat or cool a house, my question is if the system is properly sized and installed can it do the job entirely on its own?  My home is approximately 3000 sq ft, two stories.  I have rather sandy soil, no groundwater near surface that I am aware of.

 Bob, You certainly can heat your entire house. I only had a quarter acre of my one acre lot to use, without crossing my underground electric line and going near my well. For 3000 square feet that are insulated and sealed normally (Note that some older houses that are not well insulated and have air cracks to the outside would need more BTU heating and cooling) you can size the heat pump to equal the capacity written on your existing air conditioner (s) or furnace.

While there is a tendency to install bigger units than necessary, figure you would need 4 tons = 48,000 BTU.

Or more if windows and R rating are not great. says 2200 sq. ft need 3.5 tons, so decide on 4 or 4 1/2.  Are you insulated with the R23 or higher spray in soy bean biodegradable insulation? Are tyvec overlaps caulked?

Groundwater near the surface does not matter but if groundwater is at -6' depth of the geo pipe that is good.

Perhaps the Health Dept has your file that shows Deep Test Pit Classification of soils used for your septic system.  If not, check a soils map for in situ subsoil characteristics. From the soils chart on this web site, dry sand has Thermal Conductivity of 0.44 Btu/ft hr deg F versus wet sand at 1.44 This Means wet sand is 3.27 times better.  I would design more loop if there were no groundwater at -6'.

Second question, from your discussion regarding keeping the fluid in the pipes clean and no life forms from growing, I got the distinct feeling that this is a problem that has no good resolution in that the biocides, etc that one can put in the system all seem to have a corrosive affect or some other disadvantage that will require some future intervention.  Is there a reasonable routine that one can follow so this does not become a significant problem post installation?

The bacteria seems to be an issue in the computer cooling industry. The difference with geo heat is that we are seasonal and freeze our pipe each winter, killing bacteria that might otherwise proliferate in a warm indoor environment.  The solution (literally) is to use clean filtered water with a small 5 % portion of chlorinated water from a public water system.  With a spigot on line like mine, one can occasionally check the closed loop water and propylene glycol mixture, but this really is not necessary. Do not use swimming pool water with excessive chlorine that would corrode gaskets that might be located either in the heat pump or the Flow Controller pump.


Third question, 50% constant humidity seems a bit high, I understood (maybe incorrectly) that humidity levels around this percentage can contribute to growing mold, any concern regarding this?

 I hate mold, and thank you for reminding me that more air flow circulation is better to fight indoor mold. There is more circulation because the heat pump coil within the air handler is at 100 degrees versus 140 degrees for a fuel oil energized coil.  From John's chart, note that electricity to circulate air through ducts is minimal compared to electricity to produce heat or coolness.  For baseboard radiator heat, there is change to humidity, although there could be more flow circulation if radiators have 100 degree, not 140 degree circulating water.

Lastly, if I wanted a turnkey installation, who would you recommend?

Thank you, 


We are working on a list of experienced contractors. Carl at Air Professionals who installed my heat pump can give you a price for all your indoor work. Outdoor work takes some site investigation and planning work first. I suggest you gather the following paper work to give to bidding designers/contractors:

        1. Survey Maps of your house and Lot;

        2. Tax Map from Assessors office.

        3. Town Wetlands Map showing your property.

        4. Torrington Area Health District files for your home showing septic system, well, and soils data.

       5. Photos of your yard, including tree roots you wish to save.

Perhaps you can design it yourself and have Mike Wolford or another experienced excavating contractor install it for you. And of course I am happy to help too.


July 3:

Great website! Very informative. We are nearby in East Windsor. With oil
prices the way they are, I am looking into a geo system. Our house is a
2500SF Cape with an oil fired forced hot air / central AC system. We own
6 acres of gently sloping land that has a high water table in areas. My
earth exchange plan will be very similar to yours since I have access to
a back hoe and plenty of land.
With all the web searching that I have done, yours is the first that I
have encountered that used somewhat large diameter poly pipe. Most that
I have seen used 3/4 or 1" in longer lengths. I was under the impression
that longer lengths of small diameter pipe would be a better heat
exchange medium.
I have not done a formal heat loss / cooling load survey but we're
probably in the 4 ton range.
Again, I'm glad that I stumbled upon your site. I was looking for a
local HDPE pipe distributor and now I found one.



Thanks Steve.

I have trusted Target Enterprises for years, and know they can provide good geo pipe.


Prices this fall went way up and then adjusted down. By late October they were 16% higher than in May.



Infrared house 2013