Ground Source Heat Pump:Type, Efficiency,Benefit,Setup

21 May 2023

By Debarghya Roy

Introduction

Ground source heat pumps are an efficient and sustainable energy technology for space heating, cooling and hot water production. They harness the relatively constant temperature of the ground to deliver a clean and renewable form of energy with outstanding performance year-round.

Ground source heat pumps were first developed in the 1940s and their popular use has increased exponentially over recent years. Now nearly 85,000 units are installed in US homes annually. Growing concerns about fossil fuel emissions have driven many towards this clean renewable solution. Not only is it good for the environment but also boasts significant long-term cost savings.

Definition And Working of ground source heat pumps

Ground source heat pumps (GSHP) are systems that can be used to transfer heat from the ground directly into a home. The system works by using ground loop pipes buried several feet below the Earth’s surface that fill with fluid and absorb natural energy coming from the Earth.

This heated liquid is then run through a compressor and circulated around radiators or air-blown ducts to warm up a house. Finally, the cool liquid is pumped back outside where it absorbs heat again before starting another cycle. There are two types of heat pumps :

Ground source heat pumps
Air source heat source

Ground source heat pumps Vs Air source heat pumps

Ground-source heat pumps offer several advantages compared to their air-source counterparts, including higher efficiency, lower operating costs, and a reduced environmental impact. The following table highlights the key differences between them :

Aspect	Ground Source Heat Pump	Air Source Heat Pump
Efficiency	Ground source heat pumps have efficiency rates ranging from 300% to 600%, making them more efficient than air source heat pumps.	Air source heat pumps typically have efficiency rates ranging from 200% to 300%, which is lower than ground source heat pumps.
Operating Cost	Operating costs for ground source heat pumps are generally lower due to their higher efficiency, which leads to significant energy savings over time.	While air source heat pumps are still more efficient than traditional heating systems, they tend to have higher operating costs compared to ground source heat pumps.
Environmental Impact	Ground source heat pumps produce fewer greenhouse gasses and have a smaller carbon footprint compared to air source heat pumps, making them a more environmentally friendly option.	Air source heat pumps produce more greenhouse gas and have a larger carbon footprint than ground source heat pumps.
Installation Cost	Initial installation costs for ground source heat pumps tend to be higher due to the need for ground loop installation, but these costs can be offset by long-term energy savings and available incentives and rebates.	Air source heat pumps generally have lower installation costs, but may not offer the same long-term energy savings or incentives as ground source heat pumps.

In conclusion, while both ground source and air source heat pumps provide an efficient and eco-friendly alternative to traditional heating and cooling systems, ground source heat pumps often have the edge in terms of efficiency, operating costs, and environmental impact.

Types Of Ground Source Heat Pump Systems

There are various types of ground source heat pump systems available for energy efficiency, including closed-loop, vertical,and hybrid systems.

Closed-Loop Systems

Closed-loop geothermal systems are the most commonly used ground source heat pump type. A closed-loop system circulates a mixture of water and antifreeze in pipes buried vertically or horizontally in the ground.

Depending on your property’s size, layout and orientation, there are several ways to install these systems: vertical loops, horizontal loops and pond/lake designs. The major advantage of this loop design over other types is that it can be located anywhere since it does not rely on having access to a body of permanently existing water like an open-loop system would.

The consistent temperature underground enables the pump to extract enough heat during winter to provide efficient space heating, as much as 4 times more efficient than air-source heat pumps! In summer seasons, when cooling is desired, the process works in reverse by extracting warmth from inside buildings before releasing it back into the ambient environment outdoors through the earth loop.

And because this cycle happens without involving any warming or cooling agents like refrigerants which degrade easily with time, maintenance requirements for closed-loop systems are generally minimal compared to other types such as air source models.

Vertical Systems

One of the more popular types of ground source heat pumps is the vertical system. This system involves drilling boreholes up to 400 feet deep into the earth and connecting a U-shaped loop of pipes at each depth, which can then connect to an indoor heat pump unit.

By using longer, deeper loops, this type of system requires less surface area than most other types. Additionally, it’s suitable for buildings with limited land space or where excavation isn’t feasible due to soil properties.

The vertical systems are relatively easy to install due to their smaller footprint requirements when compared with some open-loop systems that require large manpower resources for drilling multiple wells, but overall costs could increase accumulated from narrower holes in comparison with open-looped options.

It has been used successfully in commercial buildings such as hotel complexes and apartment blocks; retail complexes like malls; stadiums including polo grounds and soccer fields as well as multi-story residences in urban areas where typical installations don’t offer many viable solutions for lack of adequate room located onsite or larger lot sizes incurred elsewhere on residential landscape design standards.

Hybrid Systems

Hybrid ground-coupled heat pumps (HyGCHPs) are a type that combines the technology of ground-source heat pump systems with solar energy systems. This combination can offer significant benefits in terms of energy efficiency and cost savings compared to air-source heat pumps, as the warmer source water temperature is closer to ambient air temperatures than that of other geothermal sources.

In addition to providing efficient heating and cooling capabilities due to their hybrid nature, HyGCHPs also reduce greenhouse gas emissions compared to traditional fossil fuel sources as they do not emit carbon into the atmosphere upon operation.

The design of such a hybrid system includes several components, including a set point controller, an aquifer thermal store, a boiler venturi flow control valve, surface collectors for producing hot water directly from sunrays, vertical or horizontal circulating loops connected with groundwater sources at certain depths spanning up to 200 feet deep; and certain types of hydraulic equipment used for transferring collected solar energy between two distinct liquid fluids like meltwater mixed brine in order to increase overall effectiveness during performance operations.

How Much Does A Ground Source Heat Pump Cost?

The cost of a ground source heat pump varies from $10,000 to $30,000 based on the system size and complexity. Factors such as drilling, electrical work, and additional components will affect the total installation cost.

Factors In Calculating The Cost

Ground source heat pump installations can vary significantly in cost, with many variables impacting the bottom line. The size of the system, the condition of the site it will be installed, the type of loop system, and available tax incentives and rebates all contribute to the overall expense of installation.
Factors such as local labor costs, drilling requirements for horizontal or vertical systems, the number of loops needed, and supplier access influence pricing.
A more extensive system will increase capital expenditures upfront but may offer more significant energy savings over time if properly maintained. For example, a large residence requires more loops than a tiny home would need and, therefore, would have a corresponding higher initial cost likely offset by lower operational expenses due to its increased efficiency in cooling or heating an entire house.
Furthermore, having existing underground infrastructure onsite could reduce potential excavation costs associated with borehole projects since no digging may be done if working pipelines are already underground.

Tax Incentives And Rebates For Installing A Heat Pump

Installing a ground source heat pump can be a significant investment, but federal and state tax incentives and rebates can help offset the cost. One of the primary tax incentives available to homeowners and businesses is the Federal Geothermal Tax Credit, which covers expenses associated with the installation of ground source heat pumps. Here’s a snapshot of what you need to know about this tax credit:

Attribute	Details
Filed Through	Form 5695
Credit Amount in 2021	30% of the installation cost
Credit Amount in 2023	22% of the installation cost
Commercial vs. Residential	Available for both residential and commercial installations
Eligibility	Must meet Energy Star criteria

Additional Costs And Considerations

When considering installing a ground source heat pump system, it is crucial to recognize that there are additional costs and considerations.

First, the site must be evaluated for suitability, and design specifications must be prepared to ensure proper equipment sizing. This can include assessing geologic formations for open-loop systems and measuring space requirements for closed-loop horizontal, vertical, or pond/lake systems.
After installation, regular filter changes and annual inspections should be performed to maintain maximum efficiency and cost savings.
Also, having available incentives such as energy rebates and tax credits, which can bring down initial installation costs substantially while helping reduce long-term operational expenses even further, is essential.
To maximize energy savings and life expectancy of components like pumps, filters, defrost controls, etc., manufacturers’ recommendations must be followed when selecting the right parts, along with necessary repairing or upgrading services when required.

Benefits Of Using Ground Source Heat Pumps

Installing a ground source heat pump in your home or business can provide significant financial, environmental, and comfort benefits.

Reason	Fact
Energy Efficiency	Ground source heat pumps can reduce energy consumption for heating and cooling by up to 50% compared to conventional systems.
Cost Savings	The average homeowner can save between $400 to $1,500 annually on heating and cooling costs with a ground source heat pump system.
Tax Credits	Federal tax credits of up to 26% can be claimed on the cost and installation of a ground source heat pump system (as of 2021).
Lifespan	The ground loop component of a ground source heat pump system is predicted to last more than 50 to 200 years.
Maintenance	Ground source heat pumps have a lower risk of malfunction, with a failure rate of less than 1% per year.
CO₂ Emissions Reduction	Installing a ground source heat pump can result in a 44% reduction in CO₂ emissions compared to using natural gas heating.
Renewable Energy Use	Geothermal energy accounts for approximately 3.7% of renewable energy consumption in the United States.
Heating/Cooling Performance	Ground source heat pumps can reach a coefficient of performance (COP) of up to 5.0, meaning they produce 5 units of heat for every unit of energy consumed.
Noise Reduction	Ground source heat pumps operate more quietly than conventional heating and cooling systems, with noise levels below 50 dB.
Property Value Increase	Installing a ground source heat pump system can increase a property’s value by an average of 5%.
Initial Investment Recovery Time	The initial investment in a ground source heat pump system can be recouped in energy savings within 5 to 10 years.
Scalability and Flexibility	Ground source heat pump systems can be scaled and adapted to various building sizes and heating/cooling needs.
Job Creation	The geothermal industry has created over 35,000 jobs in the United States, with future growth expected.

Factors To Consider When Installing A Ground source heat pump

When installing a ground source heat pump, it is important to consider the site suitability, installation costs, available incentives and rebates, maintenance requirements, and troubleshooting.

Site Suitability: Assessing the site’s suitability for ground source heat pump installation is essential. We consider the following facts:

Soil features:

The type of soil can affect the heat transfer rates.
Different soil types (sand, loam, clay) have different thermal conductivities.
Soil moisture content can also influence the effectiveness of the heat pump.

Climate requirements:

Ground source heat pumps work best in moderate climates where the ground temperature is relatively stable.
Extreme hot or cold climates might affect the efficiency of the system.
Average air temperatures, seasonal variations, and the depth at which the ground temperature remains constant are all important considerations.

Available land area:

The size of the land area determines the type of ground loop system that can be installed.
Vertical boreholes, one type of ground loop system, typically require an area of approximately 500 to 1,000 square feet per ton of heating and cooling capacity.
Other types of systems, like horizontal loops, may require more or less space, depending on the design.
The available land area also influences the total capacity of the heating and cooling system that can be installed.

Installation Costs: The installation costs of a ground source heat pump system vary based on the site characteristics.

Installation Costs:

The cost for installing ground source heat pumps typically ranges from $20,000 to $25,000 per ton of heating and cooling capacity.
This cost can vary depending on various factors including the specific heat pump model, the size of the area being heated or cooled, and local installation costs.

Additional Expenses:

Complex installations may lead to additional expenses.One such complex installation method is directional drilling.
The cost for directional drilling typically adds approximately $2,000 to $5,000 per borehole to the overall installation cost.
Other potential additional expenses could include site preparation, landscaping after installation, and any necessary modifications to the existing heating/cooling system.

Overall Budget Considerations:

When planning for a ground source heat pump installation, both the basic installation costs and any potential additional expenses should be taken into account.
The total cost can vary significantly depending on the complexity of the installation and the specific characteristics of the site.
It’s also important to consider the long-term energy savings that a ground source heat pump can provide, which can offset some of the initial installation cost over time.

Available Incentives: Many regions provide incentives and rebates to promote the adoption of ground-source heat pumps. In the United States, for example, homeowners can take advantage of the federal Residential Renewable Energy Tax Credit, which offers a 26% tax credit on the total system cost. State-level incentives and utility rebates can further reduce the upfront costs by several thousand dollars. The following table provides an overview of the incentives and rebates available for installing ground-source heat pumps:

Type of Incentive	Description
State Programs	Various state-level programs offer incentives for installing ground-source heat pumps, including grants, rebates, and low-interest loans.
Federal Tax Credits	The Inflation Reduction Act of 2022 provides tax credits for geothermal heat pump systems. The credit amount depends on the type of system installed and other requirements.
Payback Time	The payback time for installing a ground-source heat pump depends on factors such as electricity, equipment, installation costs, and the number of incentives available.

4. Maintenance Requirements and Troubleshooting: Regular maintenance and troubleshooting of ground source heat pump systems are crucial for optimal performance and energy efficiency. The annual inspection of all system components can help prevent major repairs or replacements.

Common issues include air leaks in underground loop systems, incorrect pump performance due to filter screen and check valve neglect, corrosion or mineral build-up due to weather conditions, and wiring issues leading to control or electrical problems. Regular inspections and tune-ups of components like motors or reversing valves can prevent potential issues.

Periodic water tests for proper pH balance are necessary to prevent scaling build-up, which can significantly reduce efficiency if left unchecked.

5.Upgrading and Replacing Components: Upgrading or replacing components, such as compressors, heat exchangers, and electrical parts, can improve the performance and efficiency of a ground source heat pump. Switching from single-speed compressors to variable-speed models or upgrading from direct-drive motors can yield significant energy savings by offering better temperature regulation.

High-efficiency upgrades include advanced digital controls for more precise temperature regulation, improved fan motors that consume less energy and operate at lower noise levels, and insulated cabinet designs to prevent condensation loss and reduce external noise.

Installation Of Ground Source Heat Pumps

Heat Pump Installation

Proper installation of ground source heat pumps is a critical part of the process, as it ensures optimal performance and longevity of the system. A properly sized, designed and installed ground source heat pump system can provide efficient heating and cooling for up to 25 years or more.

Site Evaluation And Design

An evaluation of the proposed site to determine if it has suitable conditions for installing a ground source heat pump such as soil type, land slope, access points etc. This evaluation will also guide size requirements and possible excavation depths .

Loop field layouts may vary depending on climate zone and soil type but they are typically horizontal trenches if space allows or vertical borehole systems if there’s limited room available.

Ground Loop Installation

After this assessment the excavation process begins where large machinery is used to dig deep holes below the frost line according to layout preference followed by pipe connection in horizontals or coils with U-shaped loops placed inside holes in vertical installations.

Then piping between loops needs to be connected using couplings before everything can be refilled back into place.

Image: Ground Loop Installation

System Testing And Commissioning

System testing and commissioning is an essential part of installing a ground source heat pump (GHP) system. During this process, the performance and efficiency of the GHP system will be evaluated to ensure that it functions properly.
This includes tests on the different components and systems within the GHP installation such as the piping network, control valves, pumps, sensors, and blowers; verifying refrigerant charge levels; ensuring all safety features are working correctly; performing pressure drop tests across filter screens or meter readings for closed loop systems; testing pump flow rates; checking supply water temperatures against design conditions etc. Some instruments may also be used during these tests such as data loggers for temperature monitoring and thermocouples for constant temperature readings.
All test results should be recorded accurately so any deviations from expectations can be determined quickly in order to take corrective action if necessary.

Maintenance Of Ground Source Heat Pumps

Regular filter changes and annual inspections for ground source heat pumps are essential for ensuring their performance and longevity. Without regular maintenance, dirt, dust and other debris can clog air filters resulting in poor air flow within the system which lowers efficiency.

Furthermore, annual inspections are important as this allows trained technicians to diagnose any existing or potential issues before they become larger problems. This includes checking for pipe deterioration or water quality issues in geothermal systems so adjustments can be made to ensure optimal performance.

Inspections will identify areas of improvement such as cleaning flash plates to reduce the risk of sediments entering the combustion chamber which may affect second-stage operation or damaging surface temperatures with high condensation level if not addressed early on.

FAQs:

1. What is a Ground Source Heat Pump?

A ground source heat pump (GSHP) uses the heat stored in the earth’s soil to provide energy efficient heating and cooling, by transferring energy from one system to another. The GSHP circulates a liquid between underground pipes which absorbs heat from the earth before delivering it into your property as hot water or warm air.

2. How efficient are ground source heat pumps?

Ground source heat pumps are highly efficient; typically providing up to four kilowatts of renewable energy for every single kilowatt used over their lifetime providing savings of up to 70% compared with traditional fuel sources such as gas or oil boilers. This can significantly reduce long term running costs while protecting against volatile prices caused by fluctuating markets and global supply chain issues that wouldn’t be felt otherwise when using other forms of dated technology present throughout typical “off-the-grid” homes today.

3. Are there any advantages associated with having a ground source heat pump installed?

Yes, not only do these systems provide an incredibly cost effective form of heating but they also effectively protect against environmental damage/pollution found through more traditional methods such no longer relying upon burning fossil fuels, producing little noise and emissions being generated on site during operation either due to located being placed deep beneath surface , so users won’t suffer external disruption usually associated with unsightly smoke stacks visible around local neighborhood(s).

Conclusion

Ground source heat pumps are an increasingly popular choice in cities around the world looking for a sustainable and energy-efficient alternative to traditional heating and cooling systems.

They offer a number of advantages over airsource systems, including improved indoor air quality, better overall efficiency due to their direct connection with ground temperatures, cost savings through reduced energy bills, and extended system lifespan thanks to low maintenance requirements.