ClimateMaster
Geothermal
What, When,
Where, & How
What Is
Geothermal?
Boiler/Tower
Systems
Ground-Source
(Geothermal)
Several Variations of
Geothermal
 Vertical Closed Loop
 Horizontal Closed Loop
 Hybrid (Geo and Tower/Boiler)
 Lake Closed Loop
 Closed to the Aquifer
 Standing Column Well
Vertical Loop System
Avg Depth
Avg Depth
Avg Depth
Verticals
When Loops are
shallower than
one ton per loop
One Pair
Two Pair
Series/Parallel One Pair
Vertical Loops
• 3/4” pipe - One vertical bore per ton. One
circuit and 3 gpm flow per ton.
• Many areas require bentonite grouting
• Some locales restrict drilling
• Bore per ton
– Cold climates 150 ft per ton
– Warm climates 230 ft per ton
Horizontal Loop System
(Slinky shown)
2 ft
2 ft
2 ft
2 ft
2 ft
Two-Pipe
Four-Pipe
Six-Pipe
Back-Hoe Loops
1 ft
2 ft
Horizontal
Loop Types
Two-Pipe
Four-Pipe
Trenched Loops
Extended Slinky
Horizontal Loops
• Limited tonnage due to land area
• Backhoe or trench excavation. In areas with
any rock typically backhoe only.
• 1 circuit and 3 gpm flow per ton w/ 3/4” pipe
• Pipe per ton
– Cold Climates - 400 to 1000 ft
– Warm Climates - 700 to 1800 ft
Ground Source - Closed Loops
• Benefits
– Lower maintenance
– No water requirements
• Hurdles
– Requires land space
– First cost
Ground Loop
• 3 gpm flow per ton of cooling
• 1 circuit or flow path per ton of cooling w/ 3/4”
loop pipe
• Loop Temperatures
– 40 - 90 deg F
Hybrid Systems
Hybrid Loops
 Ground Loop/Tower
 Ground Loop/Boiler
 Benefits:
– Off Peak Operation
– Low First Cost
Lake Loop System
Concrete
Blocks for
weight
Reverse Return
Header
3 foot separation
Heavy Duty Plastic
Safety matting
Nylon Cable Ties
to secure blocks
Nylon Cable Ties
to secure Netting
and bricks
4 ft between coils
300 ft coil per ton
separated by scrap
pipe
Traditional Coiled Pond Loop
- Southern Climates
8-10 Bricks for
weight
300 ft slinky coil
per ton
High Efficiency Slinky/Matt Pond
Loop - Northern Climates
Pond Loops
• Least expensive ground loop
• Minimum 300 ft2 per ton and 9 feet deep
• In north need ice cover for operation (no
aeration). Utilizes 39 degF water temp.
• Pond should be within 300’ of structure
• 300 ft Pipe per ton
Closed to the Aquifer Systems
Ground Water - Plate Frame HX
• Benefits
– Lower first cost
– No land requirement
– Isolated internal loop via HX
• Hurdles
– Requires annual HX maintenance
– Requires injection well
– Typically used only with more than 4 total units
Standing Column Well
Ground Water - Direct Use
• Benefits
– Lowest first cost
– No land requirement
• Hurdles
–
–
–
–
Requires clean water and more maintenance
Getting rid of water can be difficult
Larger pump and pressure tank
Typically used only with 3 or less total units
Heat of extraction/rejection
Moving Heat to Water or Air
water
or
refrig
or
air
Heat of extraction
HEATING
11.6 kbtu/hr
15.3 kbtu/hr
refrig
water
WORK
air
1.08 kw=3.680 kbtu/hr
COP = 15.3/3.68 = 4.15
Heat of rejection
COOLING
15.2 kbtu/hr
water
12.0 kbtu/hr
refrig
work
air
0.95 kw=3.2 kbtu/hr
EER = 12.0/0.95 = 12.6
Refrigeration Circuit Overview
Suction
Air
Coil
Reversing
Valve
Expansion
Device
Coax
To Loop Source
Compressor
Discharge
Refrigeration Circuit Overview
53 F
Cooling Mode (GS036)
60 F
76 psi
Suction
80 F
Air
Coil
60 F
Reversing
Valve
Expansion
Device
62 F
Coax
92 F
9gpm
Compressor
Discharge
155 F
218 psi
90 F
100 F
To Cooling Tower
a) Lvg air coil temp is lower than ent air coil temp is due to pressure drop through air coil.
b) Suction temp at compressor is higher than lvg air coil temp because vapor continues
to superheat as it travels back to compressor.
Refrigeration Circuit Overview
168 F
Heating Mode (GS036)
66 F
86 psi
Suction
70 F
Air
Coil
107 F
62 F
Expansion
Device
96 F
59 F
Reversing
Valve
Coax
9gpm
70 F
62 F
To Boiler
Compressor
Discharge
168 F
248 psi
How did
Geothermal
Gain Momentum?
History
Behind
Geothermal
Late 70’s-Early 1980’s
• Energy crisis: Fossil fuel shortages and price
shocks
• Dependence shifts to electricity
• Opportunity builds for geothermal technology
• Technical competence for geothermal water
source heat pumps develops in the industry
Mid 1980’s
• Electric utilities experiencing “peak demands”
• DSM (demand side management) becomes a
strategic planning tool
• Extensive monitoring reveals geothermal
efficiency and market potential
• Geothermal becomes recognized as DSM
planning tool
Late 1980’s
• Performance Standards established for
geothermal systems
• Support grows from regulators, research
groups and utilities
• Substantial performance in utility DSM
programs
• A proven technology competitive with
conventional fuels
Early 1990’s
• Geothermal systems increase in performance
and functionality
• EPA, DOE, EPRI (Electric Power Research
Institute), NRECA (National Rural Electric
Cooperative Assoc), EEI (Edison Electric
Institute) recognize potential for geothermal
• Utility geothermal DSM programs begin
implementation
Mid 1990’s
• Geothermal recognized as key technology to
reduce greenhouse gases
• EPA and DOE release reports confirming
industry growth potential
• Government, utility, and industry consortium
formed to assist in the development of the
geothermal market
Late 1990’s-Year 2000
• Geothermal becomes recognized as a major
renewable energy source on an international
scale
History of Ground Source Heat
Pumps Installations
• Based upon water source heat pump from
Florida of 1950’s
• Ground loop development using iron and
copper loops 1930’s and 40’s. PB and PE
pipe made viable in late 1970’s.
• Three regions of development in 1979:
– OSU - J. Bose, J. Partin, G. Parker
– Ft Wayne, IN - Dan Ellis
– Ontario - Dave Hatherton
Antifreeze Materials
• Methanol - least expensive and good heat
heat transfer
• Ethanol - More expensive and best heat
transfer
• Propylene glycol - non-toxic and expensive,
but lowest heat transfer
Pipe and Fittings
Pipe and Fittings Material
• High Density polyethylene (HDPE )pipe
developed for natural gas distribution industry
• Socket or Butt heat fusion joints are stronger
than the pipe wall itself
• 3/4, 1, 1-1/4, 1-1/2, and 2” sizes common
• Coils and straight lengths
• Many fittings available in tee’s, elbow’s, and
couplings
Loop Design
Loop Terminology
Header
Supply/Return
Lines
Loop/Heat
Transfer Field
Loop Terminology (cont.)
Manifold
To Building
Supply/Return
Isolation
Valves
To Earth Loop
Supply/Return
Lines
Loop Design
• Loop style and total trench/bore length
obtained from software design
• Goal is 2.5 - 3 gpm flow per ton of capacity
(minimum of 2.25 gpm)
• Loop circuiting is designed for:
– Low pressure drop
– Good heat transfer
• Headers are piped in reverse return to even
out pressure drop in parallel circuits
Pumps
• Option 1 - Redundant Alternate - Size single
pump to handle complete circulation install
duplicate redundant pump in parallel and
control alternately
• Option 2 - Redundant Staged - Install two
pumps in parallel that can handle load and
stage them with alternating controls
• Option 3 - Variable speed pumps with
solenoids at each unit
• Option 4 - Distributed pumping - Install
pumps at each heat pump with single pipe
system and continuous circulation
Circuit Design rules
• 1 circuit per ton of capacity in 3/4”
• 2.5 - 3 gpm per ton of capacity
Header Design
Design Do’s and Don’ts
• Design air scoop/trap between building and
earth loops to entrap air stemming from wshp
maintenance
• Utilize Mechanical room or outside pit to
house manifold of supply/return lines with
individual shut-offs and main loop to building
• Ensure equipment is rated for temperature
range of loop WLHP, GWHP or GLHP
• In hybrid design size loop for heating load
and tower for extra cooling required
Flushing
• Flush exterior loop first using system pumps.
• Flush supply/return one at a time.
• Flush interior loop with exterior isolated so as
not to move air to earth loop
Antifreeze
• Antifreeze to 15 deg F below coldest loop
temperature expected
• Always add alcohols below water level to
reduce fumes
• Check antifreeze concentrations using the
specific gravity charts
Equipment
Components Allowing Geothermal
Oversized lanced fin /
rifled tube refrigerantto-air coil
Copeland UltraTech™
two-stage unloading
scroll compressor
Insulated Refrig Circuit
Large coaxial
refrigerant-to-water Bidirectional TXV
heat exchanger
Ground source versus air source
•
•
•
•
Water has better heat transfer than air
Improved low temp heating capacity
Lower peak demand
Outdoor ambient conditions, damage, and
vandalism
• Noisy and unsightly outdoor unit
• Better dehumidification
• Higher efficiencies
ARI Ratings Summary
• ARI/ISO/ASHARE 13256-1 Ground loop heat
pump
– Based upon typical extreme loop temperatures
– Htg 32 degF and clg 77 degF
Comparative Analysis of LifeCycle Costs of Heat Pumps
 Lincoln,
NE school district compared
leading systems for 3 new schools:
System
150 Tons
$/sq. ft.
Geothermal WLHP
$1,021,257
$14.66
Air Cooled Recip Chiller/VAV
$1,129,286
$16.21
Water Cooled Cent Chiller/VAV
$1,164,268
$16.71
• Note: Air Cooled Chiller is 1kw/ton. Water Cooled Chiller is
0.6kw/ton. Vertical Bore Loop Field cost is $2.50 included in
the Geo WLHP cost.
Garrett Office Buildings
Edmond, Oklahoma
Geothermal Building
20,000 Sq. Ft.
VAV Building
15,000 Sq. Ft.
Floor 2
Conference
Floor 2 Private Office
Floor 2 Open Office Space
Geothermal Building
Floor 2 Heat Pump Zoning
HP-15
HP-14
HP-13
HP-9,10
HP-12
HP-8
HP-11
Loop Field Overview
Geothermal Building
Loop Field Site Plan
Loop
Field
Details
Geothermal
Mechanical
Room
CWS
Backflow Preventor
Heat Pump
Return
Heat Pump
Supply
Pressure Reducer/Relief
3/4”
Expansion
2” PE typical
Air Vent
Air
Separator
Geothermal
Mechanical
Room
Bypass
3” Copper
125 GPM @ 70’
Pumps
Primary/Standby
Charging
2” PE typical
Ground Loop
Ground Loop
Floor 1 Heat Pump Piping
Garrett Office Buildings
Highway View
Geothermal Building
Roof View
VAV Building
Roof View
VAV Building
Central Air Handler
VAV Building
Air-Cooled Condensing Unit
VAV Building
Boiler Room
Garrett Office Buildings 2000 Energy Consumption
VAV 15,000 ft^2
Gas Mcf
Elec kWh
36.2
12,400
21.0
14,720
6.9
13,600
4.3
15,760
3.5
17,920
4.2
18,560
3.2
21,280
3.2
23,520
3.2
18,720
11.2
16,080
21.9
12,720
69.4
13,600
188.2
198,880
Month
Jan-00
Feb-00
Mar-00
Apr-00
May-00
Jun-00
Jul-00
Aug-00
Sep-00
Oct-00
Nov-00
Dec-00
Total
$ Cost
$
1,882
$
17,899
Geothermal 20,000 ft^2
Gas Mcf
Elec kWh
0.0
9,920
0.0
10,880
0.0
9,960
0.0
10,120
0.0
11,600
0.0
12,400
0.0
13,120
0.0
14,480
0.0
11,120
0.0
9,840
0.0
10,360
0.0
13,600
0.0
137,400
$
$
10,992
Garrett Office Buildings
2000 Energy Consumption Profile
Garrett Office Buildings
Installation Costs
• Geothermal System circa 1998
– Complete exterior loop, mechanical room,
interior PE piping, flushing and unit startup, heat
pumps, duct work, exhausts, MUA system,
timeclock-based controls
– $128,700 ($2,574 per ton)
• VAV System circa 1987
– air-cooled condenser, VAV air handler, boiler,
VAV boxes with reheat coils, economizer,
electronic controls
– $100,000 ($2000 per ton)
– costs per building owner do not include
structural or architectural
ClimateMaster
Geothermal
Heat Pumps