Searching for GeoThermal System Info

Searching for GeoThermal Heating & Cooling information.
It’s been a while since I have seen a system in person. Homeowner was useless for any info as the system was installed a couple years before he purchased, and he got nothing from the seller he purchased from.
Anybody have any experience, words of wisdom, or a link to a QUALITY site for research and education?
Don’t bother mentioning Internachi as I’ve already searched their archives and only found menial comments, mostly 10-15 years old, and from past questionable members. I actually got more from the US EPA site… Geothermal Heating and Cooling Technologies | US EPA
Appreciate any assistance.
Thanks in advance.

From yesterday…

maybe here,
but it is a .gov site, so might be redundant to what you already found. not much of that stuff here in south florida


I haven’t had time to check this out but seems to be the company.


Jeffrey, not exactly sure what you’re looking for specifically, but these are some of my concerns for what observations I make on geothermal.

As far as the refrigeration part, it is all the same, except it uses water exchange rather than air. Head pressure will be lower on a hot day. They can be run on a cold day outdoors without concern for freeze ups or compressor damage because the water temperature is basically about the same between winter and summer. Keeps the pressures of the refrigeration from working at below freezing temperatures that ice up coils in cool weather, but when you still have a cooling load inside the house to take care of. I.e. lots of glass.

My biggest concern is the water system.
What is the source? It can be a ground loop, a well, a river/stream or pond.

What type of heat exchanger between the water and the refrigeration circuits. I.e. shell and tube, tube in a tube. Some work better than others. Quality of water used makes a difference and affects maintenance requirements.

Scaling from the water will happen in the condenser heat exchanger, and there may be water treatment issues for maintenance to be concerned about. Some heat pumps go into an extremely cold reverse cycle that actually the strips the interior of this heat exchanging system of its scale.

I’ve had a lot of trouble with low water table during droughts sucking up sand and other issues of North.

The longevity of the equipment generally will last much longer i.e. the compressor. Because water is more efficient in removing heat, head pressures on the compressor remain much lower and are not stressed under high temperature, clogged up outdoor condensing coils, and the defrost cycle of a heat pump. These systems do not have a defrost cycle which is highly inefficient on a normal air source heat pump. In a normal heat pump, you take the heat out of the house to defrost ice on the outdoor coil and all of the auxiliary electric heat coils come on to keep you from freezing yourself from this cycle that occurs every 45 minutes-hour and a half range depending on geographically where the heat pump is located.

You have pumps instead of fans. Check amperage draw on those during an inspection.

The systems are actually very simple with less complicated circuit boards and sensors. Again, water source, potential leaks, and volume/flow are usually the big repairs.

Finding servicemen to work on these restrict availability of qualified technicians.

Your header says geo thermal systems; I’m assuming you’re talking about Ground Source Heat (Water Source) Pumps not Geothermal, which in the field mean something different. Kind of like people calling refrigerant Freon. Geo Thermal sounds more high-tech and impressive to people from the EPA and such.

Hope that touches on it a little for you. Have any questions, get hold of me.


Geocomfort Model and Serial numbers please.
1: Check for recalls.
2: Link to Geocomfort Installation & Operations Manual above.

I enjoyed your geothermal summary. Could you elaborate some on your comments about “head pressure.” Are there concerns about the head pressure? I have not heard of compressor damage in cold weather, which we have in abundance. BTW, while there is some geo in Colorado, I’ve yet to see my first system. But I get questions about it.
A neighbor (30 miles away) put in one on a home similar to mine. Her system cost $30K. (We are both on 35 acres & propane.) She told me that her utility cost was down to $250 a month! I nodded, but thought, my utility cost is about $250/month and I still have $30K in my pocket. I assume geo is not all equal and makes more sense in some situations than others.

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Lon- sorry for the response delay, I was out of town on a regional single action cowboy match.

Head pressure: this is the highside pressure being discharged out of the compressor into the condenser coils. If the condenser cannot remove sufficient heat (for numerous reasons) the pressure goes up.

Temperature/pressure are relative dependent upon the type of refrigerant. So for R-22 refrigerant we generally do not like to see the pressure over 260 psi. The head pressure varies with the outdoor air temperature on an air cooled condenser, and we generally like to see refrigerant temperature/pressure of the system not significantly more than 30° F above the outdoor air temperature. (90°F +30°F = 120° F. Converts to 260 psi). Anything significantly higher than 260 psi indicates a problem at the condenser i.e. airflow, dirty coils, excessive refrigerant charge and in geothermal, water flow problems.

When the temperature becomes excessive, the liquid refrigerant that comes out of the condenser, heading to the evaporator coil has too much heat and as it passes through the metering device some of the refrigerant must flash off to cool the liquid refrigerant entering the evaporator coil (this is an efficiency loss). Head pressure/temperature also increases the evaporator pressure/temperature. So at 69 psi you may have a coil around 40°F. Raise the psi with the head pressure to 76 psi, then the evaporator coil temperature goes up about 5°. You can’t cool the house to the design temperature/moisture if those temperatures are too high. It is inefficient and takes more time to accomplish its purpose.

As for your question on compressor damage during cold weather: the opposite is happening as I described above. The condenser lowers the refrigerant temperature/pressure too much, which drops the evaporator temperature/pressure below the freezing point. (If you drop evaporator pressure 3 psi, the evaporator temperature will drop below freezing, depending on the heat load within the house, which is why I recommend running the heat before testing the operation of the air conditioner). Reciprocal Refrigeration compressors have extremely tight headspace clearance between the piston and the head of the compressor (for best efficiency) and any oil or liquid refrigerant which does not have any space within that clarence becomes a hydraulic force that generally breaks the valves or crankshaft. This does not apply to scroll compressors which can handle this slugging of refrigerant, however it’s extremely noisy and significantly inefficient. Refrigerant slugging also washes the oil out of the compressor and you’re running the compressor dry.

Yes, they are very expensive initially and they can be much more expensive to maintain, but they are very efficient because of what we discussed above. The system runs under much lower pressure which uses less horsepower, thus less electricity, and the heat of compression which accelerates metal fatigue is hardly there. You may also want to note that the refrigerant in the system has a primary job of cooling the compressor after it cools the house. That is why we want the section line coming back to the condenser to be cold and sweaty. The house may be cooling down perfectly fine but if that section line is hot, it’s like running your vehicle without antifreeze.

So next, people are going to say, we don’t have all these gauges to do this. If you understand the temperature/pressure correlation above you can determine these factors just by the temperature of the components. You can use a thermometer (if you know what you’re going to do with those temperature readings), or you can simply use your hand. If the section line feels like a cold beer, the superheat is probably fine. You can even just look at it; if it’s dry you probably want to touch it and see. If there’s ice on it you have an overcharged system or air restriction (dirty filter). As for the small refrigerant line coming out of the condenser, you should not feel any significant heat. The body (your hand) is 98°. The outdoor air span falls within this temperature range and you should not feel significant heat. If it’s cold you have a problem. If it burns your hand you have a problem.

As for equipment not being equal; there are different types of geothermal and yes they are not all equal in efficiency. System design will determine what this is (not your purview) but under any working design, geothermal operates under much lower temperatures than is experienced from the outdoor air. If you have a heat pump, there’s more heat in the ground/water in the winter than in the air, and the ground/water is always cooler than the air in the summer. Its ability to remove heat mathematically determines your savings.

Longevity of the equipment is always longer than air cooled equipment if properly designed and installed.

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To be honest, I’m not exactly sure myself. I see these systems so infrequently, that I have not made it much of a priority to learn more about them. I think that needs to change for the near future. I suspect they will become a bigger part of our lives as technology improves and the systems eventually (?) come down in cost to make it more of an actual option (such as with Solar Panels) with an actual benefit.

Dave, I appreciate all your posts on this MB, and especially in reply to my query. Last weeks and today’s posts are both great, even if I am trying to fully comprehend what you are explaining for everyone’s benefit. Thank you much!!

Thanks also to everyone else that is taking their time to contribute to this discussion. I think it’s long overdue that we move towards the future with topics such as this. Much of the education on the site is geared towards the newbie inspector. Internachi needs to step it up and pay more attention to the longtime veteran inspectors that need to stay current with new or updated technologies.
Thanks all!!

The problem Jeffrey!

I have a bunch of this stuff stuck in my head that I’ll never use again, just hope somebody can make use of it! :slight_smile:

I also have come across very few residential geothermal systems, even though I live in the land of electricity (TVA). I’ve worked on a lot of commercial and industrial applications over the years. I have worked in the State of Kentucky, who put geothermal in all of their school construction.

The primary problem I found there was water supply. They were drilling two 8 inch Wells per facility, one for supply and one for discharge.

The other problem was that Train/Ingersoll-Rand were building these to specification, not a product line, and some of the fans and compressors were running backwards because they were three-phase. I was just there for the computer control systems, but I ended up having to fix things that weren’t right when they came online.

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Well, if nobody else, I am learning from your ‘affliction’!! :wink:
Thank you!

Wow! What a great explanation!
Frankly, I’ve had trouble getting info that seems reliable on Geo partially because, most websites and everyone I talk to around here who knows much about it, is in the geo business and are gung-ho promoters of geo.

For instance, your comment about scaling (in your earlier post) is very applicable around here because most of our natural water sources (ground and river) are typically hard to extremely hard. But I never hear anyone say more than a passing advisory about that. (Ditto about scaling in tankless water heaters)

So a question…regarding compressors. It seems that the information I see about regular AC & heat pumps, scroll compressors are most common. Are reciprocating pumps more common in geo systems?

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Sorry, but I’m older than dirt! I’m used to seeing Recipts in residential in days gone by…
You are correct, Scroll is #1 these days.

I provided that info because you may just come across one,as they do last a long time in some geo locations.

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Well, if we are going to talk age or shooting stuff…dirt calls me dad and I have a new double barrel double trigger shotgun with English style stock. All are firsts for me and the learning curve is killing me. I look like I picked up a shotgun for the first time. The quail around me are dying of old age.


:rofl: :+1: (;ksdjshlvksdjhdflkh)