Richard Simmons Drilling Company, Inc.

60 Drill Rig Drive, Buchanan, Virginia 24066 Telephone (540) 254-2289

Geothermal Heating & Cooling How it Works

1. Air Source Heat Pump – Heating Mode 2. Air Source Heat Pump – Cooling Mode 3. Geothermal Heat Pump – Heating Mode 4. Geothermal Heat Pump – Cooling Mode 5. Advantages of a Geothermal Heat Pump

Heat Pumps

Background

Heat is the flow of energy from one body or substance to another due to a difference in temperature.

To heat the interior of a building, energy must be extracted from a source and transferred to interior air.

Heat Pumps

Background

First Law of Thermodynamics

– Energy cannot be created or destroyed. It exists in the universe in a fixed amount. It can be stored, and can be transferred from one material to another.

Second Law of

Thermodynamics - energy generally cannot spontaneously flow from a material at lower temperature to a material at higher temperature.

Heat Pumps

Background

Water does not move spontaneously, but can be pumped from point A to point B, and can even be made to flow uphill by a

water pump

, powered by an outside source of energy.

Likewise, energy can be relocated and elevated (from a lower temperature to a higher temperature) by a

heat pump

.

Heat Pumps

Background

Consider a heat pump that is heating the interior of a building during winter. Outdoor energy at 45 degrees F will be transferred to indoor air whose temperature is 70 degrees F.

Any substance at any temperature has internal energy. The energy in outdoor air at 45 degees F is readily available and is free, and so can be part of the energy needed indoors. An additional energy input will be required to satisfy the 2 nd Law of Thermodynamics. i.e., before energy can be transferred to indoor air, temperature must be elevated to above 70 degrees F.

Heat Pumps

Background

Energy can be transferred into and out of a

refrigerant

closed loop.

flowing in a Two heat exchangers plus an additional source of purchased energy are required.

The refrigerant will evaporate in one heat exchanger and condense in the other. Evaporation will occur when the refrigerant absorbs energy and condensation will occur when it gives up energy.

Heat Pumps

Background

Evaporation will occur at a certain temperature that is dependent on pressure (Ex.- water boils at 212 degrees F

at atmospheric pressure

. Water temperature can be raised above 212 degrees in a pressure cooker without evaporation occuring.) Likewise, condensation temperature (dew point) can be controlled by manipulating pressure.

The operation of a heat pump is dependent on manipulation of the pressure, the boiling point, and the dew point of the refrigerant. This allows heat transfers to occur within the range of temperatures typically found inside and outside a building.

Air Source Heat Pump

–

Heating Mode

Indoors Outdoors Temperature T2 > T1 The refrigerant enters the evaporator at a pressure such that its boiling point temperature is less than T2. It evaporates and exits as a vapor, having absorbed energy from outdoor air.

It will need to circulate through the loop, give up its energy, and return to the evaporator as a cold liquid.

Refrigerant Vapor Temperatue = T2 Outdoor air (Heat Source) Temperatue = T2 Temperatue = T1 Cold mixture of liquid and vaporized refrigerant Heat Exchanger (Evaporator) Cooled outdoor air

Air Source Heat Pump

–

Heating Mode

Indoors Hot refrigerant vapor Temperatue = T3 Outdoors Compressor Refrigerant Vapor Temperatue = T2 Compression elevates the pressure, the temperature, and the dew point of the refrigerant.

Since T3 > 70 degrees, energy can now be transferred to indoor air and the refrigerant is at a pressure such that it will condense at 70 degrees.

$$ Outdoor air (Heat Source) Temperatue = T2 Temperatue = T1 Cold mixture of liquid and vaporized refrigerant Heat Exchanger (Evaporator) Cooled outdoor air

Air Source Heat Pump

–

Heating Mode

Indoors Hot refrigerant vapor Temperatue = T3 Outdoors Compressor Refrigerant Vapor Temperatue = T2 Heat Exchanger (Condenser) $$ Outdoor air (Heat Source) Return Air Temperatue = T2 Supply Air (Heat Sink) Refrigerant gives up most of its absorbed energy to interior air in condenser. Refrigerant exits condenser as a cool liquid.

Temperatue = T1 Cold mixture of liquid and vaporized refrigerant Heat Exchanger (Evaporator) Cooled outdoor air

Air Source Heat Pump

–

Heating Mode

The pressure, temperature, and boiling point are suddenly reduced by the expansion valve and the refrigerant is ready to return to the evaporaor.

Indoors Hot refrigerant vapor Temperatue = T3 Heat Exchanger (Condenser) Outdoors Compressor $$ Refrigerant Vapor Temperatue = T2 Outdoor air (Heat Source) Supply Air (Heat Sink) Return Air Temperatue = T2 Cool Liquid Refrigerant Expansion Valve Temperatue = T1 Cold mixture of liquid and vaporized refrigerant Heat Exchanger (Evaporator) Cooled outdoor air

Air Source Heat Pump

–

Heating Mode

Supply Air (Heat Sink) Indoors Hot refrigerant vapor Temperatue = T3 Outdoors Compressor Refrigerant Vapor Temperatue = T2 Heat Exchanger (Condenser) $$ Outdoor air (Heat Source) Return Air Temperatue = T2 Cool Liquid Refrigerant Expansion Valve Temperatue = T1 Cold mixture of liquid and vaporized refrigerant Heat Exchanger (Evaporator) Cooled outdoor air

Air Source Heat Pump

–

Cooling Mode

A heat pump is a reversible process. To cool the interior of a building, the refrigerant flow is reversed. The evaporator and condenser swap functions. Interior air at 70 degrees F is the heat source, and exterior air at 90 degrees F is the heat sink.

Air Source Heat Pump

–

Cooling Mode

Return air (Heat Source) Indoors Warm refrigerant vapor Outdoors Compressor Hot refrigerant Vapor Heat Exchanger (Evaporator) $$ Outdoor air Supply air Cold mixture of liquid and vaporized refrigerant Expansion Valve Cool, pressurized liquid refrigerant Heat Exchanger (Condenser) Heated outdoor air (Heat Sink)

Heat Pumps

Background

An air source heat pump requires a backup heat system when in the heating mode, and when outside air temperature is low.

Air Source Heat Pump – Heating Mode

Backup Heating System

Hot refrigerant vapor Return air The auxiliary heat source can be electric or a furnace burning fossil fuel.

Heat Exchanger (Condenser) Auxiliary Heat Source Supply air (Heat Sink) Cool, pressurized liquid refrigerant $$

Geothermal Heat Pump

–

Heating Mode

The earth's temperature underground is constant at about 56 degrees F. Thus, it is almost always warmer than the air above it during winter, and cooler during summer.

A geothermal system in heating mode utilizes the earth as the heat source. A closed loop circulating water system flows from the evaporator to the earth and back again. Energy is transferred from the earth to the water, then from the water to the refrigerant.

Geothermal Heat Pump

–

Heating Mode

Compressor $ Warm refrigerant vapor Evaporator Cold refrigerant liquid and vapor mix Expansion Valve Indoors Outdoors The earth replaces outdoor air as the heat source.

An underground circulating water system transfers energy from the earth to the evaporating refrigerant.

Above ground Below ground Earth (Heat Source) Circulating water supply from earth Circulating water return to earth

Geothermal Heat Pump

–

Cooling Mode

In a geothermal system in cooling mode, the earth replaces outside air as the heat sink.

Geothermal Heat Pump

–

Cooling Mode

Compressor Hot refrigerant Vapor Hot Water Heater $ Desuperheater Indoors Condenser Cool, pressurized Liquid refrigerant Expansion Valve Outdoors The earth replaces outdoor air as the heat sink.

An underground circulating water system transfers energy from the condensing refrigerant to the earth.

Waste heat returning to earth is exchanged to the hot water heater.

Above ground Below ground Earth (Heat Sink) Circulating water supply from earth Circulating water return to earth

Geothermal Heat Pumps

Underground Circulating Water System

There are two types of underground water systems used with geothermal heating and cooling systems: Closed loop o

Vertical – water is circulated through piping in geothermal wells.

o

Horizontal – water is circulated in horizontal piping at least five feet underground.

Open loop – water is pumped from the aquifer through a well, utilized by the heat pump system, then returned to the earth through a well.

Geothermal Heat Pumps

Advantages

• • • • • • •

Reduced operating costs

– 70% in electricity costs.

Reduced carbon emissions

a geothermal system can save 30 to – power plant emissions are reduced by approximately 44%.

Reduced demand for foreign oil imports.

No visible machinery or components outdoors.

Backup heating system never required.

Quiet

– the compressor is installed indoors in a garage or storage room and normally cannot be heard.

Tax credits

– federal and state governments frequently offer income tax credits to encourage installation of geothermal systems. A tax consultant should be consulted.

Geothermal Heat Pumps

Cost Considerations (1)

Installation costs are higher than for air source systems and operating costs are lower. The period to recover excess installation costs depends on the cost of electricity and the size of the building. The recovery period for a system installed now is not static – as electricity costs increase over time, the recovery period decreases.

As of December, 2008, there is a reasonably good chance that the US Congress will enact “ cap and trade ” or “ carbon tax ” legislation. Such legislation might significantly increase the cost of electrical power. That would reduce cost recovery periods, and should increase resale value of a building equipped with a geothermal system.

Geothermal Heat Pumps

Cost Considerations (2)

Cost recovery periods are generally acceptable for larger homes and for institutional buildings, such as school or office buildings. Environmental considerations may influence the building owner when deciding whether a projected recovery period is acceptable.

If a geothermal system will be financed by a long-term mortgage, a study should be made to determine whether the additional cost of the monthly mortgage payment will be offset by monthly savings in the cost of electricity.

Richard Simmons Drilling Co., Inc.

What We Do

We install underground circulating water systems that are components of geothermal heating and cooling systems.

We act as a contractor in cooperation with an HVAC contractor, or as subcontractor to a general contractor.

We will be happy to visit with you, or talk to you by phone, to initiate a conversation about geothermal systems.

Call today to begin, telephone (540) 254-2289

Stephen Brooks Geothermal Manager