Commercial / Residential
Applications
Why Water?
• Most efficient
• 5,1 cm water pipe = 61 cm
air duct
• Less space
• Higher mass and thermal
conductivity
• Benefit of thermal storage
Why WSHP?
• COP ~ 5
Efficiency 500%
• Boilers/fossil fuel furnaces < 100%
• More compact than Air cooled
• Linked to outdoor WB or deep
earth temperatures ----->Higher
efficiencies and longer service life
Why Geothermal?
• Less dependency on
Temperature variations ~
Constant Ground temperature
• Utilizes the natural thermal
properties of earth.
• Eliminates boiler and heat
rejecter installation.
• Eliminates all outdoor
equipment
• Reduces mechanical room
space
• Single zone applications
• Higher efficiency
Open Loop Applications
• Open Vertical loop with a recharge well
Well ----->Heat Pump ----->Separate recharge well
• Open Vertical loop with a Surface discharge
Well ----->Heat Pump ----->Pond , Stream or River
• Open Loop surface water system
Pond,Stream,river ----->Heat Pump ----->Water body
Open Loop-Thumb rules
• Water well which can produce
2,0 to 2,6 l/m per kW
• Water quality must be good to
prevent fouling and clogging of
pipes
• Ground water from a fresh
water aquifer better than surface
water
– constant temperature
– thermodynamic advantage
– Surface water - organic
materials
Open Loop-Thumb rules
• Shut off valves for ease of
servicing
• Boiler drains - tee’d for acid
flushing
• P/T plugs to measure
temperature and pressure
• Cu HX recommended
• Cu-Ni HX -Heavy scale
• Expansion tank to minimize
mineral formation by air
exposure
• Water control valve(Slow
closing) on discharge line to
prevent mineral precipitation
Closed Loop Applications
• Vertical Borehole loop
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Least land space
High excavation/drilling costs
Holes drilled 45-180 m
Typical hole 10 cm diameter
for each 3 to 4 kW of cooling
capacity
– Minimal spacing is about 3 m
– U-shaped pipe (HDPE)
– Computer model determines
exact length.
Closed Loop Applications
• Horizontal trenched or bored
loop
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More land space
Low excavation costs
Less expensive installation
Straight length U-tube laid flat
in wide trenches
– Typical depth is 1,5 m
– Polyethylene coil tube (flat
Slinky)
Cost Comparison for decision
Vertical, Horizontal straight tube, Horizontal Slinky
• Parameters
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Land
Cost of pipe
Cost of trenching
Cost of Excavation
• Example
• Vertical 122 m deep BHE requires 21 sq m SA with wells separated by 5
m=HHE 2.5 m trench will have to be 183 m in length with 5m separation
= 848 m of land/40 times land area
• Straight pipe - Higher trenching cost
• Slinky - Higher pipe costs
Soil/Rock Conditions
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Open Loops
– Simple
– Can the aquifer support the
volume extraction and
injection?
Closed Loops
– Large soil categories
• Dry soil
• wet soil
• saturated soil
– Solid rocks (granite, igneous
rocks) - Highest thermal
conductivity
– Dry sands and clay - Lowest
thermal conductivity
Grouting
• Why Grout?
– Drilling geothermal boreholes
• Surface water penetrates
downward into the aquifer
• Hydraulic characteristics of
aquifer degraded
– Bentonite (Clay) + Water --->
Swells 10 to 20 times volume
– forms a gel with low viscosity
and semi-rigid when set
– Good seal between upper and
lower aquifers
Geothermal and Hydronics
• Most acceptable indoor climate
Floor temperature: 19 and 29°C
Air temp at head level: 20 and 24°C
• Air convection methods - Warm,
buoyant air rises wastefully to the
ceiling in convection-heated rooms,
warming the upper body
• A simple heating element is installed
beneath the flooring
• Warms the lower part of both the room
and the body - convects from the
radiant floor surface
Geothermal and Hydronics
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Radiant floor heating with water- water heat pumps
Buffer tank
– control flow rates through the unit
– Typically 13 litres/kW
– Electric water heaters
Hybrid Systems
• Cost not justified for a GHP with
uneven demands
• Cooling demand >> Heating demand
– Cooling tower
• Heating demand >> Cooling demand
– Boiler
• First cost low
Benefits
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Year round individual control
Tenant metering
Quiet operation
Minimizes downtime
– Failure affects the single zone served
Low overall Life cycle cost
Low operational costs
Higher comfort
Health and safety
– eliminates the need for onsite fossil fuel combustion
Low maintenance
Longer service life
Benefits
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Hedge against Fuel Savings
Space/Structural savings
Higher comfort
Reduced emissions
– eliminates the need for onsite fossil fuel combustion
• Simpler to design
• Simpler to control
• Simpler to commission
Green/Sustainable design
• Certification programs/Incentives
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Energy efficiency
Geothermal
Enhanced refrigerant management
Functionality, flexibility, maintainability
Lower operational environmental impacts
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USGBC - LEED
BREEAM in UK
VROM in Netherlands
DENA in Germany, Austria and 11 Euro Nations
Thank You
Arun Shenoy
ClimateMaster Inc
ashenoy@climatemaster.com