Ground Source Heating and Cooling

7/30/2019 Ground Source Heating and Cooling

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Geothermal++++++

Earth Energy


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Geo means Earth

Thermal means Heat

Geothermal energy is the natural heat of the Earth

Earth energy is sub-surface heat from the Sun


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Capturing Geothermal EnergyThe 1st System

In 1904 1st demonstration. Emerging steam powered a turbine to light

5 light bulbs

Worlds 1st Geothermal Power Station. 1911 in Tuscany, Italy

By 1913 a 250 kW power station had been built and was used to power the

Italian electric railway system. Today world production is 5 TWh, or 10%


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Earth Energy Heat PumpA heat pump is an electrical device

that extracts heat from one placeand transfers it to another


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Capturing Earth Energy I

Geothermal Heat Pumps can provide heat in thewinter and cool air in the summer best of both

worlds

Residential and commercial/institutional scale is

available.

Geothermal heat pumps can be used anywhere inthe world without a geothermal reservoir. The

insulating properties of the earth, just below our

feet, can keep us warm or cool !!


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Energy Under Our Feet

47% of Solar Energy is Absorbed

By the Ground

19% Absorbed by

Water Vapor & Dust

4% Absorbed

By Clouds

17% Reflected

By Clouds6% Absorbed

By Surface


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Terms to Know Refrigerant. Liquid/gaseous substance that circulates through the heat pump,

alternately adsorbing, transferring and releasing heat. Commonly usedrefrigerants are distinguished by the fact that over a relatively moderate range

of elevated pressures, they vaporize and condense at temperatures that can

generate spontaneous heat flow to maintain interior building comfort

Classified as hydro-chloro-fluoro-carbons (HCFC), or chloro-fluoro-carbons (CFC).

Todays refrigerants are designed to have minimal impact on the atmosphere by eliminating

the chlorine (hydro-fluoro-carbons)

COP. Coefficient of Performance is a measure of a heat pumps efficiency. It is

determined by dividing the energy output or the heat pump in BTU/hr by the

electrical energy needed in watts to run the pump, at a specific temperature.

The higher the COP, the more efficient the pump.

EER. Energy Efficiency Ratio measures the steady state cooling efficiency of a

heat pump. It is determined by dividing the cooling capacity of the pump in

BTU/hr by the electrical energy input in watts at a specific temperature


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More Terms

to KnowCompressor. It squeezes themolecules of the refrigerant, gastogether, increasing the temperature

of the refrigerant shifting it to avapor phase

Evaporator. A coil in which the

refrigerant absorbs heat from the

soil/water and boils to become a low

temperature vapor.Condenser. A coil in which the

refrigerant gives off heat to its

surroundings as it condenses back

into a liquid.

Expansion Device. Lowers the pressurecreated by the compressor. This

causes the temperature to drop, and

the refrigerant becomes a low

temperature vapor/liquid mixture.Evaporator Condenser

Expansion

EvaporationCondensation

Compression

Expansion

Device

Compressor


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Ground Source Heat Pumps Source. A ground source heat uses the earth or ground water or

both as the sources of heat in the winter, and as a sink for heatremoved from your home in summer.

Access. The heat is extracted from the earth (land or water) using a

liquid, antifreeze solution, or refrigerant (direct expansion system)

The temperature of the antifreeze is raised by the heat pump

The heat is transferred to the indoor air

Summer reversal heat is taken from indoor air and transferred to the

ground

Delivery.

Forced air

Hydronic radiant

Electrical resistance base board


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Ground Source Operation I Location Entire pump system is inside, unlike air source in which

one of the heat exchangers, usually the compressor is outside

Open System

Open System takes advantage of the heat retained in underground body of

water, usually a well.

Water is drawn up directly to the heat exchanger where heat is extracted

Discharge is to a stream, lake or pond, where permitted, or a discharge

well.

Closed System

Collects the heat through an underground system of piping.

An antifreeze solution, or refrigerant, which has been chilled by the heat

pumps refrigeration system to several degrees colder than the soil/water

circulates through the piping and absorbs heat from the soil


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Ground Source Operation II Heat Cycle

The antifreeze solution or refrigerant (heat carrier) which has circulated

through the piping and absorbed heat is brought back to the heat pump

in the building.

In the ground water or antifreeze system the carrier passes through the refrigerant

filled primary heat exchanger and transfers the heat In the direct expansion (DX) system the refrigerant enters the compressor directly with

no intermediate heat exchanger

The heat is transferred to the refrigerant, which boils to become a low

temperature vapor - it then goes to the compressor In the open system the ground water is pumped back to the discharge well

In the closed system the heat carrier is pumped through the outdoor piping to be

reheated again


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Ground Source Operation III A reversing valve directs the refrigerant vapor to the compressor at

which point the vapor is compressed by reducing the volume and

increasing its temperature.

The reversing value then directs the hotter vapor (gas) to the

condenser coils.

Here it gives up heat to:

Air blowing across the coil and through the duct system to heat the home

Water flowing across the coils and to the radiators in the rooms

Having given up the heat, the refrigerant passes through the

expansion device where the temperature and pressure are decreased

further before returning the the first heat exchanger, or to the DX

system, to begin the cycle again


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Technology & OperationHow the Heat Pump Works

Heat pumps transfer heat bycirculating refrigerant through acycle of alternating evaporation

and condensation.

A compressor pumps therefrigerant between 2 heatexchanger coils.

In one coil, the refrigerant isevaporated at low pressure andabsorbs heat from its surroundings(blue in the soil/water).

The refrigerant is then compressedin route to the other coil where itcondenses at high pressure (red)

At this point, it releases the heat itabsorbed earlier in the cycle (intothe home)

Earth Home

Compression

Condensation

Expansion

Evaporation

Evaporator Condenser

Low PressureLow Temperature Liquid

High PressureHigh Temperature Liquid

Low Pressure

Low TemperatureLiquid

Low PressureLow Temperature

Liquid


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Heat Pump Ground Loops I

Points to Consider

Size of the system

Ground loop design

Soil Type, Depth and

Consistency

Land area available


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Heat Pump Ground Loops II

Vertical

Most appropriate for suburban homeswhere lot space may be restricted.

Pipe inserted into bore holes 6 inches

by 60-200 feet, depending on soil type

and system size

100 m piping per ton of heat capacity(3.5kW or 12,000 BTU)

DX systems smaller holes, less cost

Horizontal

Rural areas with more property

Piping in trenches 3 to 6 m deep

150 m piping per ton of heat capacity

Well insulated 2,000 sq.ft. home

would use 360 to 540 m pipe


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Heat Pump Ground Loops III Regardless of the arrangement

chosen, all piping for refrigerantor antifreeze solution systems

must be polyethylene or

polybutylene with thermally fused

joints to ensure leak free

connections for life of the pipe, or

25 to 75 years.

DX systems use copper pipe that is

of refrigeration grade.

Or

PolyethyleneCopper


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Heat Pump Ground Loops

Multi-Unit Dwellings

Same principles apply for commercial/institutional settings

In room systems compartmentalized and operate independently

Integration with Solar PV can help optimize benefits


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Pipe Installation

New Construction Sites

More Rural

Retro-fit Construction Sites

More Urban


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Earth Energy - Advantages

Uses 25% - 50% less energy than conventional heating andcooling

Improved humidity control

Can be retrofitted

Long lasting, quiet and easily accessible Less expensive to operate and maintain

Investment return of 3 to 10 years.or less

It can work in land or waterlots of flexibility

They conserve fossil fuel reserves and enable their use forhigher value products

They provide clean heating and cooling with no emissionsfrom burning fuels


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Earth Energy - Disadvantages

High initial cost, particularly for retrofitting

Horizontal ground loop systems which are the least

expensive require a hectare This can be addressed by combining vertical and slinky

systems to reduce spatial requirements

A qualified installer is recommended. However, this

does open the door to financial grants that do not

come with a do it yourself operation


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Benefits of Heat Pumps

They can be used almost everywhere world wide

They are energy and cost efficient

They conserve fossil fuel reserves and enable their

use for higher value products

They provide clean heating and cooling with noemissions from burning fuels (depending on

electricity source)


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Geothermal Benefits

Replacing your natural gas

furnace is equivalent to

parking 2 cars for a year.

EPA: Geothermal heat pump

systems are the most energy

efficient, environmentally

clean, and cost effective

space conditioning systemsavailable

Originates from

the electricity

source


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Summer/Winter Operation

Winter Heating Cycle Winter Cooling Cycle

Documents

Ground Source Heating and Cooling