View Full Version : Geothermal - Put your excavator to good use!

01-29-2008, 12:17 AM
Make a difference while making a profit!
Many of you on this part of the forum have the equipment and skills to add a new service to your business while also helping to conserve energy and the environment.

Geothermal ground loops can be installed using track excavators and loaders, and are an excellent system to save up to 60% on heating and air conditioning bills. More information can be found at the Geothermal Heat Pump Consortium - www.geoexchange.us (http://www.geoexchange.us). Some ground loops are installed vertically with well drilling equipment, while others can be installed in a horizontal configuration which is more cost effective and therefore frequently the preferred installation. Obviously, many here on this forum can be involved and profit in this endeavor with equipment that they already own. A search for geothermal contractors or engineers in your area will probably turn up a nice source of work for yourselves. There are already over one million geoexchange systems installed in the United States, so this is no longer a fringe technology.

There is not a single person I know who wouldn't want to save 60% on their heating and air conditioning bills. Geothermal energy is both energy efficient and environmentally friendly and will become more and more popular as traditional fuel prices maintain their upward trend. Many states already have generous rebates, some as high as $600 per ton, for new geothermal systems.

Below is a photo of a ground loop we recently installed in New Jersey. This system is 7 tons and required 3600 feet of piping in the ground. It can provide heating, air conditioning, and hot water at significant savings of approximately 60%. The trenches were seven to eight feet deep and about 42" wide. A hydraulic screener was used to sift away the stones to keep them off of the ground loop without needing to buy any sand. Note the smooth trench bottom despite the rock vein in the middle of the photo. The HDPE piping will last for over 100 years, so a little extra precaution is well worth the effort.
Geothermal - A smart investment that is good for the country and great for the environment!

Dirt Digger2
01-29-2008, 12:46 AM
we dig a lot of geo-thermal trenches for a well drilling company around here...not really that profitable...not really a whole lot of digging involved for a "typical" field

Az Gardener
01-29-2008, 12:50 AM
Thank you for the link. We are designing a new home now and want to use geothermal but no one in Az does it.. I have contacted a accredited designer in Ca. and she wants 2500 just for the design. So I am looking for other options for the design part.

We will be doing the install ourselves, my father in law is an old Colorado farmer and HVAC guy so he thinks he knows what needs to be done but we would like some confirmation.

That part is kind of on the back burner for now as we are dealing with setbacks, variances and slow draftsmen. But I will probably contact you later to "pick your brain".

01-29-2008, 01:08 AM
There is a guy i know that does this with a core drill and does it the vertical way.One of the reason this is used is when you don't have a big area to work in.Doesn't take much room going straight down.I think he usually drills three holes.

Uses a backhoe and it core drill mounted on a truck,plus his supply truck.

He keeps busy ,especially with the high price of heating fuel.I would consider this if i was building now days.I would do the horzinal with my own equipment and having enough room to install.

Last time i visited with him,he did say that now the state is trying to get it passed to be certified and having to get permits ,since he gets into under ground water table the way he is doing it.

Nice tip for someone wanting to expand there work options.

AWJ Services
01-29-2008, 09:24 AM
Most Geothermal equipment is 3 to 5 times that of conventional Heat pumps with the 60% savings not an accurate number over the new high seer conventional equipment.
The equipment should be less price due to fact that it is easier to build with less components.
The pump that runs the ground loop can and do fail regularly in my area with the high loads put on the ac/cooling units.the pumps are rather pricey too and if swayed from the geothermal units speccs any damage to the unit from an inferior pump will void the warranty.

An average 3 ton heat pump installed here is around 4000 dollars.
A geo thermal will run 12 to 15 k.

They also rate the Heat pump and the Geo thermal in 2 different specs to further confuse the consumer.

Modern heat pumps are pushing 14 +seer ratings and most geo thermals overall will only get in the high teens seer ratings.
Expect 20 to 30 % savings.
The Ground loop is tough to engineer in some areas to get rated efficiencies.

On an average electric bill of 200 a month in can take upwards of 15 + years to recoup the savings.

01-29-2008, 11:47 AM
I've only done one, 3 big woven "balls" and back filled with sand. It's cheaper in the long run in our region.

Dirt Digger2
01-29-2008, 11:54 AM
i understand how it cools the water but what i don't understand is how you can get heat out of the ground unless you are drilling way way down...in which case i dont see how the savings cost can overshadow the initial cost...someone enlighten me please

RockSet N' Grade
01-29-2008, 12:27 PM
Someone will correct me if I am wrong, but my general understanding is this. At a ground depth of 10-12', the earth remains a constant temp of around 52 degrees. This is the "heat source" you are tapping into. So, your fluid encased in piping picks up this temp and transfers it back. So now you have air coming back into the house of 52 degrees and it costs less to heat that or cool that in your environment vs. the outside air temp (which in our area varies from 108 in summer to -15 in the winter).

RockSet N' Grade
01-29-2008, 12:33 PM
Another thing I have found in my research on geothermal is that a good designer can "tweek" a standard geo system with the use of a passive solar collector (for heating) and increase the efficiency of the system another 20% on the heat side.

01-29-2008, 09:40 PM
Lots of good questions and points.

Az - It would be a good idea to know that your design is going to work before you start digging. On a new home, geo is a good way to go. In New Jersey, horizontal closed loop systems do not fall under the State's well drilling regulations like vertical bores do because they do not go through several layers of aquifers. It is important for the system to be designed properly as there are many engineering factors that are taken into consideration such as characteristics of the soil such as specific heat and moisture content, heat loss rates of the structure, friction losses, water velocity through the loop field, pump curve characteristics, and proper equipment sizing to name a few.

Dirt digger - The geothermal system extracts heat from the constant ground temperature in the same way that your refrigerator/ freezer extracts heat from inside the cold box and blows that heat out the back. (http://en.wikipedia.org/wiki/Heat_pump) The ground does not need to be hotter than 55 degrees to for the system to blow 100 degree hot air. Even though the ground is 55 degrees, there is still heat to be extracted as the loop fluid will leave the geothermal unit at a lower temperature than it was when it entered it. It then warms up in the loop field and returns to the unit for more heat extraction. This process continues all winter. A compressor, condenser, and evaporator are used with a refrigerant that has a low boiling point. When mater undergoes a phase change from liquid to gas (or liquid to solid), latent heat energy is absorbed or released to effect that phase change, and is the principal behind modern refrigerators and heat pumps. A geothermal unit has a reversing valve that can reverse the direction of flow and allow it to heat and cool.

Horizontal loops will provide plenty of earth moving for an excavating company on every installation.

Awj - Of course it is going to cost more for the first cost, but that is the price one will pay to have a steady cash flow (savings) on their investment. After an initial investment, you will see a return every year. Geothermal systems are typically more cost effective on larger installations, though they will still provide a decent return to the owner on a properly designed smaller system. Your efficiencies are incorrect: An 038 unit by waterfurnace can achieve an efficiency rating of 30 SEER, and many of their units have seer ratings in the 20 to 25 range. Their specifications are here. (http://www.waterfurnace.com/products.aspx?pl=&prd=Envision) Smaller units tend to be more efficient than larger units. An older central air conditioner can have a seer rating of only 10 or 12 for comparison. On the heating side, a properly designed ground loop will always out perform an air to air heat exchanger as the incoming loop temperature will be higher than the ambient air, and cause the efficiency to be increased.

AWJ Services
01-29-2008, 10:04 PM
an efficiency rating of 30 SEER,

30 EER / 5 COP (ARI 13256-1 GLHP)

You see that is eer not seer.

SEER is related to the Energy Efficiency Ratio (EER) which is the ratio of cooling capacity in Btu/Hr and the input power in watts W at a given operating point and also to the coefficient of performance (COP) commonly used in thermodynamics. COP is a unitless measure of efficiency. The COP of a heat pump is determined by dividing the energy output of the heat pump in watts W by the electrical energy in watts W needed to run the heat pump. The higher the COP, the more efficient the heat pump. For example resistive heat has a COP = 1. The EER is the efficiency rating for the equipment at a particular pair of external and internal temperatures. EER is related to COP by the converting the cooling capacity from watts W to Btu/Hr by multiplying by 3.413 Btu/Hr/W.

The SEER is calculated over a range of expected external temperatures (i.e., the temperature distribution for the geographical location of the SEER test). Formulas for the approximate conversion between SEER and EER or COP in California are: [2]

SEER = EER ÷ 0.9
SEER = COP x 3.792
EER = COP x 3.413
From equation (2) above, a SEER of 13 is approximately equivalent to a COP of 3.43, which means that 3.43 units of heat energy are removed from indoors per unit of work energy used to run the heat pump.

The relationship between SEER and EER is relative depending on where you live because equipment performance is dependent of air temperatures, humidities, and pressures. The relationship stated above is typical if you live in the lower-elevation portions of California; however, if you live in Georgia it is better approximated by

SEER = EER ÷ 0.80

due to the much higher humidities. A similar relationship exists in relating SEER and COP, also depending on where you live.

[edit] US Government SEER Standards
Today, it is rare to see systems rated below SEER 9 in the United States because aging, existing units are being replaced with new, higher efficiency units. The United States now requires that residential systems manufactured after 2005 have a minimum SEER rating of 13, although window units are exempt from this law so their SEERs are still around 10.[3] Substantial energy savings can be obtained from more efficient systems. For example by upgrading from SEER 9 to SEER 13, the power consumption is reduced by 30% (equal to 1 - 9/13). It is claimed that this can result in an energy savings valued at up to US$300 per year depending on the usage rate and the cost of electricity.

With existing units that are still functional and when the time value of money is considered, most often retaining existing units rather than proactively replacing them is the most cost effective. Maintenance should be performed regularly to keep their efficiencies as high as possible.

But when either replacing equipment, or specifying new installations, a variety of SEERs are available. For most applications, the minimum or near-minimum SEER units are most cost effective, but the longer the cooling seasons, the higher the electricity costs, and the longer the purchasers will own the systems, incrementally higher SEER units are justified. Residential split-system ACs of SEER 18 or more are now available, but at substantial cost premiums over the standard SEER 13 units.


I am very well versed in this field.
Lake loops do the best.

Remember that that the whole principle behind HVAC is based on Latent heat of Fusion/Vaporization.
You take the inlet temp to the condenser and the outlet temp and that is best case scenario at the evap.
The geo thermal principle can provide a better drop.

But the facts are geothermal up to 4 times the initial cost of a 15 + seer system and real world results of only a 20 seer end result happen often.
Sorry thats real life not a salesman speech.
But a 30 eer in Ga is equal to a 24 Seer.
So a 30% best case scenario will only net you a 60 dollar a month savings or a 720 dollar a year savings which end result will take a s much as 10 years to get money ahead.The avearge life of a heat pump is around 7 years.

You do the math:nono:

We cool 8 to 10 months out of the year.

Dirt Digger2
01-29-2008, 10:20 PM
Horizontal loops will provide plenty of earth moving for an excavating company on every installation.


how big of loops are you doing?...i know when we have to dig these things we just schedule to be on the job putting in a septic or drywell when the drilling crew is out there...when i get my work done and my labor is laying pipe or raking stone i drive down, dig the loop, then go back to my labor. At most theres probably 3 hours worth of work between digging and backfilling on the loops we dig with a backhoe

01-30-2008, 12:54 AM
Geothermal units are evaluated on EER because they operate indoors and away from seasonal temperature swings.
As I wrote, larger installations are generally more cost effective on a per ton basis because the costs of the loop field, though larger, are amortized over a larger system size. This is why they can be frequently found in larger homes and over 600 schools across the country. In your example, you are not factoring the savings on free hot water for your 8 to 10 month cooling season from a desuperheater equipped geo unit. That can be $35 a month additional savings on top of the electric savings.

According to a study conducted by the CEC, "air coil contamination and weathering causes standard plate fin coil equipment to lose 27% of its efficiency over the first 18 months of after installation. Thus, a 10 ton air-coupled system with a rated 10 SEER becomes a real 7.5 ton system with a real 7.5 SEER. Since earth coupled systems are installed inside the facility, there are no such losses. System capacities and equipment EER values are maintained, which results in faster paybacks and greater system dependability. Thus, a minimum 12 EER system stays at 12 EER, and a 10 ton system performs as a 10 ton system."

In any case, a geothermal system is more efficient than traditional equipment, lasts longer because it is stored indoors and away from the weather, it will add value to a property as well as provide a return on investment that will exceed anything you can get from a bank. Plus it's good for the environment, provides work for Americans and reduces demand for foreign sources of fuel. Who wouldn't want that?

01-30-2008, 01:03 AM
With your equipment and a property that has some space, you can dig a horizontal loop in place of the vertical loops that you have seen. The work becomes yours instead of the well drillers. I guarantee you it will take more than three hours to do it...

In my area, it can cost nearly $15 - $20,000 to hire a well driller for vertical bores at a residence.

AWJ Services
01-30-2008, 01:14 AM
I am not arguing that geothermal unit is not more efficient but at there current cost they will not pan out in the long run for the average homeowner.
The unit will help with hot water but only when the unit is running.
The pump itself that powers most of the ground loops does consume electricity and it is not figured in the seer rating.
SEER stands for Seasonal Energy Efficiency Rating and has nothing to do with inside or out side.
You obviously are in the business of pushing Geothermal.

The funny thing is the unit itself is cheaper to build and less complex than a modern Heat pump yet costs 2 to 3 times the amount from most manufacturers and for warranty claims it takes a specially trained tech to get the unit fixed.
The actual pumps for the ground loop are very expensive and do fail.
In the south the units will run for possibly 12 months of the year and the pump may need replacing as much as every 2 years.
This is info from owners that actually have the systems.
Figure up keep and maint and the cost of Geothermal goes up.
Not to mention what happens if the Ground loop fails.
I do not recall any HVAC tech having an excavator on his truck.
Half of a conventional hvac system is indoors as well.
Geothermal is not a new concept it is just a way for people to exploit the needs of the common consumer with promises of these huge savings and money in the bank.
The high costs of it are due to the manufacturers and greedy installation contractors .
I actually have a source for a quality Geothermal unit in the 3 ton size that can be installed and up and running for slightly more than a conventional unit.

Actual excavation costs are usually less than 1000 dollars so I would not say this is a barn burner for us dirt guys.

02-03-2008, 04:50 PM
SEER stands for Seasonal Energy Efficiency Rating and has nothing to do with inside or out side.
You obviously are in the business of pushing Geothermal.

I don't profit by promoting geothermal other than by the fact that I know that I will have helped others save limited resources while also helping the environment that we all share. Of course since the ground loop is in fact the single largest cost component of a geothermal system, an excavating/loop contractor (www.builditsolar.com/Projects/SpaceHeating/Builder's%20Guide%20to%20GeoThermal.pdf) can benefit substantially from installing one (see page 5).

I didn't intend for this to be a technical post, but you have got facts wrong in your last post - It is a scientific fact that it takes more energy for an air conditioner to pump heat into hot 95 degree summer temperatures that it does on a cooler 82 degree (SEER average) day. SEER takes into account a seasonal efficiency average that is raised by lower spring and fall outdoor operating temperatures. While seer does stand for Seasonal Energy Efficiency Rating, geothermal units are not rated this way because they operate indoors and with a loop field that is not adversely affected from outdoor seasonal temperature swings. As shown in the photo below, standard central air conditioner becomes less and less efficient as the outdoor temperature gets hotter and hotter and not the other way around. Actual efficiency on an ordinary air conditioner will always go down below a SEER rating as it gets hotter outside and it is in greatest demand. The EER rating on a geothermal unit is not much affected by hot summer air and therefore a more accurate measure during peak loads. It is not used to confuse the consumer.
This fact is a principal reason why geothermal is so efficient: in heating and cooling, the temperature differential between the ground loop and indoor temperature is much less than traditional air exchange.