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Construction

AutomotiveIndustry

PEXa GROUND LOOP HEAT EXCHANGE SYSTEM

RAUGEOTM

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REHAU 10.09.08- Page 2

- Geothermal overview

- Terminology

- Benefits

- HDPE piping systems

- RAUGEO system components

- PEXa ground loop pipe

- Fittings

- Manifolds- System sizing typical outputs

- Reference projects

- Regulations

RAUGEO SYSTEM

OUTLINE

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Ground source heat pumps are

- self-contained, electrically-powered systems that take advantage of the Earths

relatively constant, moderate ground temperature to provide heating, cooling, and

domestic hot water more effic iently and less expensively than would be possible

though other conventional heating and cooling technologies. IGSHPA*

*International Ground Source Heat Pump Association (IGSHPA)

www.igshpa.org

GEOTHERMAL OVERVIEW

INTRODUCTION

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GEOTHERMAL INTRODUCTION

Definitions:

- Geo (Earth) thermal (heat)

- Ground sourcea.k.a. geothermal

- Geoexchangeis also used

Units:

- BTU (British Thermal Unit)

- Heat energy required to raise 1 poundof water 1Fahrenheit

- Ton

- 1 Ton = 12,000 BTU/hr

- 1 Ton = 3.51 kW

kW (kiloWatt)- 1 kW = 3,413 BTU

TERMINOLOGY

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Ground source heat pump system types:

- Direct exchange

- A direct exchange (DX) geothermal heat pump system is a geothermal heat pump system in

which the refrigerant circulates through copper tubing placed in the ground. The refrigerant

exchanges heat directly with the soil through the walls of the copper tubing. This eliminates the

plastic water pipe and water pump to circulate water found in a water-source geothermal heat

pump.

- Open loop

- Also known as pump and dump- Closed loop

- Vertical wells

- Horizontal trenches

- Pond loops

- Thermal piles (storage)

TYPES

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Ground source heat pump systems:

- Closed loop

- Vertical wells

- Horizontal trenches

TYPES

Closed-loop ground source heat

pump system elements:

- Ground connection- Ground loop a.k.a. the Ground

heat exchanger a.k.a. GHEX

- Grout

- Antifreeze/water (fluid)

- Heat pump and controls- Pumping systems

- Indoor distribution

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From where does the energy come?

- The Earth's core?

- Radioactive decay

- This heat energy is very deep, more than 1

km

TAPPING THE EARTHS STORED ENERGY

- The sun

-Insolationimpacts the outer crust

- Vast majority of thermal energy in the top

500 feet of the Earth is from the Sun

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Energy source:

- Heat is continually supplied to the

ground in the form of solar energy

- Approximately 50% of the Suns

energy is absorbed by the Earth

- At a depth of approximately 15

feet the ground temperature

remains fairly constant (per

location), with a mean annual

Earth temperature of42-77F

(depending on latitude)

TAPPING THE EARTHS STORED ENERGY


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Heat pump in winter

Heat pump in summer

Principles:

- A geothermal system does not directly burn

fossil fuel

- Electricity is used for circulator pumps

and compressor

- A geothermal system can be used to heat or

cool a space

- When heating, a geothermal system collects

and concentrates heat from the ground and

delivers it to the building

- When cooling, a geothermal system collects

and concentrates heat from the building and

delivers it to the ground- The ground acts l ike a heat battery

- The piping ground loop is like the

battery cables

GROUND SOURCE HEAT PUMP

HOW DOES IT WORK?


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REHAU 10.09.08- Page 10

CONFIGURATIONS: CLOSED LOOP

Vertical Wells Horizontal Trenches


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REHAU 10.09.08- Page 12

COPEnergy Source

4.0

0.93

0.85

0.88

1.00

Geothermal heat pump

Natural Gas

(condensing boiler)

Fuel Oil (boiler)

Propane (boiler)

Electrical Resistance

COP = Total energy delivered

Energy purchased

ENERGY SAVINGS

COP = COEFFICIENT OF PERFORMANCE


Example:

- A geothermal system which

delivers 4 kW of heat for every 1kW of energy purchased (for

circulators and the compressor)

has a Coefficient of Performance

of4.0/1.0 = 4.0

- Some systems deliver COP

even greater than 5.0

COP is analogous to Efficiency

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REHAU 10.09.08- Page 16

1

BASIC COMPONENTS OF WATER-TO-WATER AND WATER-TO-AIR GEOTHERMAL SYSTEMS

2

3

GEOTHERMAL SYSTEM COMPONENTS

Ground Loop (vertical)Heat Pump

Radiant Heat Distribution

Forced Air Distribution

1

2

3

4

4

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REHAU 10.09.08- Page 17

GROUND LOOP PIPES

POLYETHYLENE PIPES WITH FUSED U-BEND

SYSTEM COMPONENTS

Fusion-welded HDPE single U-bend:

- High Density PolyEthylene

- 3/4, 1, 1 1/4pipes

- CTS or IPS dimensions

- Fused joints, in field or factory

- Two pipes in a bore hole (one loop)

- Field joints may be butt-fused (pipe-to-

pipe) or socket-fused (pipe-to-fitting)

Socket fusion HDPE connection

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REHAU 10.09.08- Page 18

GROUND LOOP PIPES

POLYETHYLENE PIPES WITH FUSED U-BEND

SYSTEM COMPONENTS

Fusion-welded HDPE single U-bend:

- J oints may be butt-fused (fitting-to-fitting)

or socket-fused (pipes-to-fittings)

Butt and socket fusion HDPE U-bend connection

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REHAU 10.09.08- Page 20

How to join these pipes?

- Pipes must be connected in

some sort of header

- Fusion becomes more of a

challenge in wet, cold

conditions

- Typical trench conditions

following rain or reaching

the water table

SYSTEM COMPONENTSHDPE BUTT FUSION TECHNOLOGY

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REHAU 10.09.08- Page 21

Reverse return piping arrangement:

- Field assembled manifolds of fused HDPE tees and pipes

- Headers need to step-up and step-down to forcethe fluid flow to be equal to all wells

- Larger diameter header pipes are costly and require extra fusion equipment

- Each piped U-bend must be within 5% length of one-another to avoid short circuits

- Pressure drop can become an issue

- Purging is a challenge, requiring high velocity through purge carts, lots of water and time

SYSTEM COMPONENTSTRADITIONAL HDPE MANIFOLDS

Example of step-up, step-down reverse return header with a four-well vertical system

Heat

Pump

Flow

Center

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REHAU 10.09.08- Page 22

HDPE Close Manifold :

- Field assembled manifolds of fused

HDPE tees

- Reducing tees need to step-upor

step-down

- Each piped U-bend must be within

5% length of each other to avoid

short circuits

- Purging is a challenge, requiring high

velocity through purge carts, lots of

water and time

SYSTEM COMPONENTSTRADITIONAL HDPE MANIFOLDS

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REHAU 10.09.08- Page 23

RAUPEX cross-linked polyethylene

- Radiant heating/cooling in the building

PRO-BALANCE manifold

- Connection to ground source pipes

- Increased control of flow

- Ease of installation

- Ease of operation

RAUGEO pipe in wells or ground loop

- System security

- Ease of installation

- Savings

EVERLOC fit tings

- Easy to install, secure

1

2

2

1

3

3

RAUGEO GROUND SOURCE HEAT EXCHANGE SYSTEMBASIC SYSTEM COMPONENTS OF REHAU SYSTEM

3

RAUGEO Double U-bend assembly

4

4

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REHAU 10.09.08- Page 30

PEXa PIPE CAPABILITIESENVIRONMENTAL STRESS CRACK RESISTANCE

RESISTANCE TO IMPACT, SLOW CRACK GROWTH, ROCK IMPINGEMENT, SCRATCHES

PEXa pipe in rocky native soil

PEXa has high impact resistance:

- More flexible than other piping materials

- Will not crush, kink or collapse when proper

backfill techniques are used

- Superior notch resistance

- Will not dent or crush from typical impacts

- Native backfill is usually allowed, no sand

Note: Clay is not recommended backfill due to shrinkage

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REHAU 10.09.08- Page 33

RAUGEO GROUND LOOP PIPES

Pipe dimensions:

- 3/4, 1 and 1 1/4 Inch Copper Tube Size

- PEXa, grey UV Shield

- Inside Diameter: 0.681 Inch

- Outside Diameter: 0.875 Inch

- Boxed in coil lengths 300 - 800 ft

depending on size

- Used for field systems

HORIZONTAL APPLICATIONS: RAUGEO COLLECT

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REHAU 10.09.08- Page 36

RAUGEO GROUND LOOP PIPES

U-bend packaging:

- Delivered on pallets as individual coils

VERTICAL APPLICATIONS:

SINGLE AND DOUBLE U-BENDS, CONTINUOUS U-BENDS WITHOUT JOINTS

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REHAU 10.09.08- Page 50

- Commonly used in residential applications

- Sometimes used in commercial applications where space allows

- Approximately 300 - 400 ft. of trench (600 - 800 ft. of pipe) per ton of energy required

- Variations in trench layout are acceptable

SYSTEM SIZINGCONFIGURATIONS: HORIZONTAL FIELD

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REHAU 10.09.08- Page 51

SYSTEM SIZINGCONFIGURATIONS: VERTICAL BOREHOLES

- Commonly used in commercial applications or

wherever where space is limited

- Approximately 200 ft. of borehole per ton of energy

required. This varies across the country with

different soil types, water tables, etc.

- Typical sizing is 1.5 tons per 300 feet well depth

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REHAU 10.09.08- Page 53

RAUGEO GROUND LOOP HEAT EXCHANGE SYSTEMREFERENCE PROJECTS

Documents

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