Innovations to Reduce the Cost of the Closed Loop Ground Heat Exchanger

Although we advocate installing closed loop systems for the reasons stated in my previous post, this does make it difficult for us to be competitive with the majority of other contractors who cling to “pump and dump” (open loops) in order to install geothermal heat pumps for the least cost. Unfortunately, in recessionary times like these, consumers are less concerned with life cycle and environmental costs than they are with initial installed cost. It makes no matter if their open loop system may have half the life span of a closed loop, if installing an open loop system at two thirds (or even half) the cost will get them the same utility rebates and government incentives. As I am not the greatest salesperson and have yet to find a program that shows me ROI of closed loops vs. open loops, I find myself losing these jobs more often than not. Despite all of the benefits, most potential residential geothermal consumers are unwilling to pay the additional price tag of a properly designed and installed closed loop system. This is why we need to find more significant ways to reduce the cost of the ground loop heat exchanger.

By far the largest cost component of the GHEX (ground heat exchanger) is bore drilling. In our area, typical costs to drill and install the GHEX can be anywhere from $17 to $20 per foot. At a typical bore depth of 180-200 feet per ton of cooling, a cost of $3000 to $4000 per ton for just the ground loop can send most consumers back towards open loops or conventional fossil fuel/electric systems. That is why it is essential to do a proper Manual J load analysis with all of the relevant envelope information to make sure that you are not over-sizing the equipment and pushing folks away. Another factor, at least in the metro New York area, is how relatively few certified ground loop installers and drillers there are. Fortunately, these costs are coming down as more drilling contractors get IGSHPA certified and familiar with installing closed loops as an additional revenue stream as compared to standard domestic water and geothermal wells. However, with the renewable energy tax credit sun setting in 2016, do we have time for this economy of scale to happen without some technology push? Probably not.

Rygan HPGX

Enter the entrepreneur who finds ways to wring more thermal performance and BTUs per foot out of a GHEX through innovation. Take, for example, the Thermonexus HPGX by Rygan and the Kelix Thermacouple, two GHEX innovations developed to reduce required bore depths and increase thermal performance. With a 300′, 6″ round bore, Kelix claims that their Thermacouple “supports heat transfer rates of up to 5 tons (60,000 BTUhr) with deep Earth environments rich in aquifers”. While Rygan makes no specific claim on thermal performance, they do say, “HPGX® advanced materials offer the toughest and highest yielding thermal performance of any closed geoexchange system”. The real question is, how much actual cost will installing these high thermal performance GHEX systems save the contractor and consumer? Also, how can we estimate thermal performance for these systems in different regions.

This link will take you to a data logging site that shows the live performance of three types of ground loop heat exchangers operating now. The top system is a 5 ton Earthlinked DX system (refrigerant) which we have not discussed here. The second system is a WaterFurnace Envision system operating on 2- 500′ standard U loop bores. The third system is apparently a Carrier 5 ton water source heat pump operating on a Kelix 300′ Thermacouple.

As always, to keep up to date with what’s new in HVAC technology, visit our website at airideal.com and follow us on Twitter @airideal and at our Facebook page!

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NPR on Closed Loop Geothermal Systems

Congress may be looking to de-fund public television and National Public Radio, but these are two media outlets that have always provided interesting insight into the world of green energy. Recently, this “All Things Considered” program ran a story on the benefits of closed loop geothermal systems called “Tapping the Earth For Energy Savings”. Read the story or give it a listen here and become a convert.

Of course, there are also those who are less concerned about the environmental benefits of geothermal and much more concerned about the cost and potential tax advantages. In this PBS parody of the “Iron Chef” called “Iron Accountant”, a team of tax experts competes to see who can get their client the highest deduction. And the winner is…IRS Form 5695 for Energy Efficiency Tax Credits of 30% for the installation of a geothermal heat pump system. So, if your subchapter S corporation had a good year, the best thing you can do to keep your money is to install a geothermal heat pump or solar photovoltaics.

New York Times Touts Benefits of Geothermal

Most of the testimony we read regarding the benefits and costs of a geothermal heating and air conditioning system come from the mid-west. However, if you are a local Long Islander considering going “geothermal”, this recent article in the NY Times Science section should help you with your cost/benefit analysis. It is interesting to note that Ms. Kreahling sites in her article the lack of qualified designers and installers in our area, as well as one-stop responsibility. You need a qualified, IGSHPA accredited designer and installer that will handle both the important work in the ground AND the HVAC system inside. Without that, you are asking for trouble and finger pointing by contracting yourself to several different vendors for drilling, excavating, loop installation and HVAC installation. However, you need look no further for a successful designer and installer of entire closed-loop geothermal HVAC systems.

As always, to keep up to date with what’s new in HVAC technology, visit our website at airideal.com and follow us on Twitter @airideal and at our Facebook page!

The Great Debate: Pressurized vs. Non-Pressurized Geothermal Ground Loops

When walking into another contractor’s installation, it never ceases to amaze me how differently installers approach things. This can be attributed to the lack of serious construction standards for ground source heat pump systems, the lack of qualified contractors willing to get proper accreditation and an ever-changing product landscape. Once we determined that closed ground loops were the best alternative for our equipment and our local environment (see this link), one of our other dilemmas as installers was whether to install pressurized or non-pressurized ground loops and flow centers (pumps). Most of the non-pressurized systems we had seen were installed by contractors trying to shave installation costs by using PVC for their indoor circuits. Most of these that I have seen were leaking after a year or two. Nothing beats good old HDPE fused piping to avoid closed loop leaks.

Ultimately, we decided that pressurized loops and flow centers were the best alternative for to meet our needs and those of our customers. However, there are varying opinions depending upon your perspective. I did some research and surveyed several other accredited installers and here is a summary of the potential advantages and disadvantages of each:
Non-Pressurized Loop Advantages:
• Lower installed cost than pressurized loops in HDPE or copper.
• All loops can be manifolded inside the mechanical room to aid in isolating loop blockages by using shut-off valves and the equipment to purge entrained air.
• Open loops allow the customer to check and add fluid himself (not sure if this is an advantage)
• Allows for contraction and expansion.
Non-Pressurized Loop Disadvantages:
• Potential leak of fluid if done in PVC or if customer constantly removing cap to check fluid level.
• Safety concern for customers exposed to methanol or antifreeze and its potential flammability.
• Higher potential for bacterial growth.
• Potential for the dilution of anti-freeze concentration by customers adding water to systems.
• Potential for system damage during flushing or purging if done incorrectly.
• Aesthetically not as pleasing as to piping configuration.
• Vertical lift limitations for any compresserized unit mounted above the flow center.
Pressurized Loop Advantages:
• Neater installation
• Less chance of anti-freeze dilution.
• No exposure for customer to flammable anti-freeze or fumes.
• Two flow center connections vs. three
• Easier to flush out dirt with flush cart at 6 ft. per second
• Less potential for damage to flow center
Pressurized Loop Disadvantages:
• Higher installed cost
• Potential for system loops to “go flat” over time due to temperature change and loop expansion and contraction that requires simple re-pressurization
• More difficult to isolate individual loop problems without interior manifold

As always, to keep up to date with what’s new in HVAC technology, visit our website at airideal.com and follow us on Twitter @airideal and at our Facebook page!

New Closed Loop Heat Exchanger Could Lower Installed Costs

If you’ve ever traveled through a Florida neighborhood you’ve probably seen those weird looking polyethylene manifold contraptions for solar pool heating assist.  A company called Maytal Tech is currently marketing a similar looking product called HyperLoop for use as a closed-loop heat exchanger in underwater applications such as ponds, lakes and canals.  This product is much less expensive than current submerge-able slinky or plate technologies and is much less labor intensive. The HyperLoop heat exchangers come in modular 2 ton sections that can be combined for greater capacity.  In speaking with the manufacturer’s representative, their objective is to also get approval for subterranean installation for ground loops with narrow trenches made by a small chain trencher that would lower the cost for horizontal loops as well.  For more information on this product, you can view their web site at http://tevaenergy.com/geothermal/innovation/ or view product information on HyperLoop here.

The Case for Closed-Loop Geothermal Heat Exchangers

Introduction

When choosing the type of ground loop to provide heat transfer for your geothermal heat pump system, you are presented with two primary options, closed and open loops. An open loop system uses water volume directly from a local source such as a pond or lake or a well drilled to tap below grade aquifers.  In this case, heat is moved to and from the water source directly. A closed loop is a very different system because it uses the earth as a heat transfer storage battery, moving thermal energy back and forth as the seasons dictate. There are several distinct advantages and disadvantages to both types of geo-exchange, but we make the case here for utilizing closed, vertical loops.

The primary advantage of an open loop is the cost factor. Open loop wells are considerably less costly than multiple closed-loop bore holes because only two are required in most instances; supply and rejection wells. Whereas, a properly sized closed-loop heat exchanger will require approximately 200 feet of high density polyethylene tubing per ton in vertical loops and perhaps 400 feet per ton in horizontal loops. Obviously, the additional cost here is incurred in excavation, drilling and pipe fusion, which are labor intensive tasks that are inherent in closed-loops.

If this is the case, why would one advocate the additional expense of closed-loops over open-loops?  Open-loops have historically proliferated in geothermal heating and cooling installations and closed-loops are actually now becoming the preferred method for several reasons that tip the balance away from initial installed cost. Primarily, open-loop systems have more potential problems than closed-loop systems because they bring outside water into the loop system and the heat pump (unless a plate and frame heat exchanger is utilized). Because of the uncontrolled nature of ground water, this can lead to clogging, mineral deposits, and corrosion in the system due to natural organic particles, minerals and acidity. Open loop systems also require a large supply of clean water in order to be cost effective. This often limits their use to coastal areas, and areas adjacent to lakes, rivers, streams and abundant aquifers. Wells are unpredictable by nature and water volume can dissipate or vanish at any point during a well’s life cycle, especially if proper testing and planning has not been undertaken.

Water Quality, Volume and Maintenance

A closed-loop system is more reliable and requires less maintenance in the long term. With an open-loop you are also taking the risk that the wells drilled on your property will produce as many gallons per minute of clean water necessary to make the system operate at capacity with the proper flow rate. The water should be tested for hardness, acidity and iron content before a heat pump is installed. Even water which has suitable qualities could change with time to poor quality that causes problems with corrosion and scaling.  One of the largest concerns people have with open loop systems is the potential for scale build up on the earth loop coil and desuperheater. Mineral deposits can build up inside the heat pump’s condenser. Even if a heat exchanger and filter are inserted to create an interior closed-loop to protect the heat pump, fouling can occur in the primary open loop along with diminished capacity.  Impurities, particularly iron, can eventually clog a return well. If your water has high iron content you should be sure that the discharge water is not aerated before it’s injected into a return well. Using water from a spring, pond, lake or river as a source for your heat pump system is a poor choice because of excessive particles and organic matter. They can clog a heat pump system and make it inoperable in a short time. Because of water quality, a geothermal heat pump has a much shorter system life on open-loop. Since a closed loop system simply recirculates a constant volume of clean water, system longevity increases.  Additionally, open loop well pumps are considerably larger than the small circulators used on closed-loop flow centers and require considerably more maintenance and cost to replace in the case of mechanical failure. The potential added cost of having to replace a well or its various components could outweigh the cost differential you had chosen it for to begin with.

Environmental Factors

A closed-loop system presents absolutely no environmental impact to the earth or our aquifers and this is recognized by environmental authorities. As such, no special permitting or licensing is required. In some localities, all or parts of an open-loop installation may be subject to local ordinances, codes, covenants or licensing requirements. Here on Long Island, we are lucky enough to be independent of the reservoir system for our drinking water because we have abundant clean water beneath our feet. However, this water is threatened on a daily basis by chemical run-off, pollution and aquifer cross-contamination. Typically, the upper aquifer may be unsuitable for drinking purposes and is considered gray water because of fertilizer, chemical, fuel, pollution and storm water run-off. Adding to this contamination should not be taken lightly. An improperly installed open-loop system can have a considerable environmental impact in the case of cross contamination. This is why there must be separate intake and rejection points. As such, the New York State Department of Environmental Conservation strictly regulates well water. NYS law requires driller and pump installer registration and certification for open-loop or standing column systems. Driller registration and certification is not required for closed-loop geothermal systems with boreholes drilled up to 500 feet deep. A Part 602 permit is required for all open-loop or standing column geothermal systems with boreholes drilled up to 500 feet deep. Many homeowners are unaware of these regulations and are taken advantage of by installers who do not obtain the necessary permits. This leaves the homeowner with potential legal and environmental complications.

Summary

For all of these reasons, we believe that the inherent risks associated with the installation of an open-loop system justify the additional cost of protecting your investment by installing a more reliable closed-loop system. Combine these risks along with the added longevity and system life that a closed-loop system will provide for your equipment and comfort and you will see that the added investment is well worth the potential benefits for you, your wallet and the environment.

As always, to keep up to date with what’s new in HVAC technology, visit our website at airideal.com and follow us on Twitter @airideal and at our Facebook page!

Geothermal Landslide in Heating and Air Conditioning

In the past year, we have had an onslaught of inquiries about Geothermal (also known as Geo-Exchange) HVAC. With the availability of a 30% Federal Tax Rebate on top of  local and state rebates, it is now economically viable to become “green” with your heating and cooling system. You can even finance the whole project while you wait for your rebates!

Essentially, Geo-exchange is just that, the exchange or extraction of solar energy stored in the earth. The sun’s energy is soaked up by the earth year-round and stored below the initial frost layer. Just 5 feet below the surface, the soil remains a constant 50-55 degrees F year-round. A geothermal or geo-exchange system circulates water with antifreeze through a closed ground loop piping system to capture this energy and return it to a “ground source heat pump” for compression and uses that heat to meet the demand in your building or home. The reverse process moves the heat from your home to the earth to create cooling. Unlike fossil fuel and air-to-air heat pumps, a ground source heat pump can produce 5 times the amount of energy that is consumed with virtually no carbon footprint. A typical fossil fuel furnace can produce only 80% of the energy it consumes in the form of heat and does this while polluting the atmosphere.

Wait a second. Did you say heat pump? Those things don’t work when it gets below freezing, right? WRONG. As previously explained, this is not an air-to-air source heat pump. The history of air-to-air heat pumps in the northeast has been that they were unable to produce high enough discharge air temperatures when the outdoor ambient temperature dropped below freezing. However, we aren’t using air as our heat exchange medium anymore, remember! We are using a constant ground temperature of 50-55 degrees F, even when it is freezing outside. So we don’t have the same fluctuations or temperature minimums as an air-to-air heat pump. In fact, we have left over heat which is used in an add-on heat recovery coil called a “de-superheater” which is used to preheat your domestic water heater or for radiant floor heat. You may need back up hot water heating capability in the winter (usually in the form of an electric immersion heating element), but, depending upon the size of your home or building, your primary hot water heating could be satisfied by a de-superheater in the summer. You are simply putting part of the rejected heat in the hot water and the rest back into the ground from whence it came!

There are 4 main types of geothermal heating and cooling. The first type is called “open loop” which pulls water from an open well to be used in your system and then returns it back to the aquifer via a rejection well, a standing column well or a leaching field. We don’t advocate this type of system because of the brackish nature of water and the associated minerals and alloys contained in the earth. This type of system is less expensive, but does not as long of a system life as does a “closed loop” system. It may also cause cross contamination of the aquifers if one of them contains surface pollutants. There are 3 major types of closed loop systems including vertical loops, horizontal loops and pond/lake loops. Essentially, all 3 types use a closed and fused polyethylene piping system with a flow center (or pump) to circulate the heat exchange medium (water with methanol or another antifreeze) through the ground loops and through your ground source heat pump. We advocate vertical loops bored to a depth of about 200 feet with one vertical bore per ton. A vertical system requires the least amount of acreage for the best heat exchange. There is significant cost in drilling the vertical bores and filling them with a thermally conductive grout (called Betonite), but there is better heat transfer and less property and excavation required than horizontal loops, which lie just below the frost line at 5 feet. If you have a pond near your home or building, this can also be used by sinking a system of closed loop “slinkies” to the bottom to use the water and ground temperature below the freezing surface. For a more in-depth discussion of this process and a geothermal installation, please see this October 2009 article in Popular Mechanics. You can also watch the short WaterFurnace video below.

Air Ideal is one of the largest dealers of WaterFurnace ground source heat pumps in the New York metropolitan and suburban area. We are also one of the few accredited installers who have passed WaterFurnace and the International Ground Source Heat Pump Association’s System Design, Pipe Fusion and Accredited Installers training and testing process. (IGSHPA Accredited ID # 20675-0909). We are a design/build contracting and engineering firm that is capable of working seamlessly with your architect via AutoCAD design drawings or on our own for new installations and retrofits. We conduct an energy survey and load analysis of your home or building to make sure that we size systems that meet your requirements while not wasting excess energy or cost.  We’ve set up this easy-to-use Geothermal Savings Calculator to help you see how much a geothermal system can save you.

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