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 2nd 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 flowing in a
closed loop.
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
Refrigerant Vapor
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.
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
Outdoors
Hot refrigerant vapor
Refrigerant Vapor
Temperatue = T3
Temperatue = T2
Compressor
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.
$$
Outdoor air
(Heat Source)
Temperatue = T2
Temperatue = T1
Cold mixture of liquid and
vaporized refrigerant
Heat Exchanger
(Evaporator)
Cooled outdoor air
Air Source Heat Pump – Heating Mode
Indoors
Outdoors
Hot refrigerant vapor
Refrigerant Vapor
Temperatue = T3
Temperatue = T2
Compressor
Heat Exchanger
(Condenser)
Supply Air
(Heat Sink)
Return Air
Refrigerant gives up most of its
absorbed energy to interior air in
condenser. Refrigerant exits
condenser as a cool liquid.
$$
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
The pressure,
temperature, and
boiling point are
suddenly reduced
by the expansion
valve and the
refrigerant is ready
to return to the
evaporaor.
Supply Air
(Heat Sink)
Indoors
Outdoors
Hot refrigerant vapor
Refrigerant Vapor
Temperatue = T3
Temperatue = T2
Compressor
Heat Exchanger
(Condenser)
$$
Return Air
Outdoor air
(Heat Source)
Temperatue = T2
Temperatue = T1
Cool Liquid
Refrigerant
Expansion
Valve
Cold mixture of liquid and
vaporized refrigerant
Heat Exchanger
(Evaporator)
Cooled outdoor air
Air Source Heat Pump – Heating Mode
Indoors
Outdoors
Hot refrigerant vapor
Refrigerant Vapor
Temperatue = T3
Temperatue = T2
Compressor
Heat Exchanger
(Condenser)
Supply Air
(Heat Sink)
$$
Return Air
Outdoor air
(Heat Source)
Temperatue = T2
Temperatue = T1
Cool Liquid
Refrigerant
Expansion
Valve
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
Indoors
Outdoors
Warm refrigerant vapor
Hot refrigerant Vapor
Compressor
Return air
(Heat Source)
Heat Exchanger
(Evaporator)
$$
Outdoor air
Heated outdoor air
(Heat Sink)
Supply air
Expansion Valve
Cold mixture of liquid and
vaporized refrigerant
Heat Exchanger
(Condenser)
Cool, pressurized liquid
refrigerant
Heat Pumps
Background
An air source heat pump requires a backup heat system when in
the heating mode, and when outside air temperature is low.
Air Source Heat Pump – Heating Mode
Backup Heating System
Hot refrigerant vapor
Return air
Heat Exchanger
(Condenser)
Supply air
(Heat Sink)
The auxiliary heat source
can be electric or a furnace
burning fossil fuel.
Auxiliary
Heat Source
Cool, pressurized liquid
refrigerant
$$
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
Indoors
Outdoors
Compressor
The earth replaces outdoor air as the
heat source.
$
Warm refrigerant
vapor
An underground circulating water
system transfers energy from the earth
to the evaporating refrigerant.
Evaporator
Above ground
Cold refrigerant liquid
and vapor mix
Below ground
Earth (Heat Source)
Expansion Valve
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
Indoors
Compressor
Hot refrigerant
Vapor
Hot Water
Heater
$
Desuperheater
Condenser
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
Cool, pressurized
Liquid refrigerant
Below ground
Earth (Heat Sink)
Expansion Valve
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 – a geothermal system can save 30 to
70% in electricity costs.
• Reduced carbon emissions – 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