Ground Loop Design
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Horizontal ground loops
Heat Sources
o Ground provides a highly
efficient source of heat
o Unaffected by air
temperature

Collector pipework laid horizontally

Requires large land area

Cost effective
Slinkies

Pre coiled pipework laid in trenches

Requires large land area, but less digging

Cost effective
Vertical boreholes

Closed loop pipework inserted into vertical hole

Typically 100-150m deep
o Recharged by solar energy
and rainfall

Most common in commercial buildings

Space efficient
o Ground type (thermal
conductivity) needs to be
factored into sizing
calculations
Surface water (closed loop)
o Important not to over
extract – sizing important

Extracts ground water from an underground aquifer

Efficient

Costly
o
Ideal solution where surface water (eg lake) is
available
o
Extremely efficient and cost effective
Open loop
Ground Loop Design
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Table 3 of MIS3005 can be used to help design the
ground array in conjunction with MCS022 ground heat
exchanger look up tables.
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3 Bed Semi detached.
From room by room heat losses:Space Peak Heat Load = 5.188 kW (6kW heat pump)
Annual Energy load = 11212 kWh/y
DHW load = 3438 kW/y
Heating System Radiators with a flow temperature of 50C (3 stars)
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14650
Kensa Room by room
heat loss calculator
6
6 kW heat Pump at a
flow temp of 50C
2442
11
1.7
Look up extraction tables
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14650
Kensa Room by room
heat loss calculator
6
6 kW heat Pump at a
flow temp of 50C
2442
11
Southwest
1.7
Wet Clay
44
From MCS 022
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3.4
4235.3
96.25
5
481.3
500
From Heat Emitter
Guide
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Property
2 Bed Detached Property
Peak Heat Load 3.5kW
Annual Energy Load 6580kWh
DHW annual load = 2578kWh
Underfloor at a flow temperature of 40C (5 stars) SPF 4.1
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9158
Kensa Room by room
heat loss calculator
5.1
4kW heat Pump at a
flow temp of 40C
1796
11
Southwest
1.7
Wet Clay
59
From MCS 022
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4.1
From Heat Emitter
Guide
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 Maximum Power Extracted from the ground:-
[ Box 2] x 1000 x (1- ( 1/[ Box 7]))
=5.1 x 1000 x (1-(1/4.1))
= 5.1 x 1000 x (0.756)
= 3856 W
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4.1
3856
65.36
5
326.8
400
From Heat Emitter
Guide
Slinkies
Myths:
 You need less land area – FALSE
 You need less pipe – FALSE
 They are less efficient – FALSE
 They are more likely to freeze the
ground than straight pipe – FALSE
Facts:
 You need the same land area as a
straight pipe collector
 There require only a fifth of the
digging of a straight pipe collector
 Quicker, easier and more costeffective to install
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Slinkies
Horizontal Slinky Trenches
•
Horizontally installed slinkies should be
placed in a 1.2m wide by 1.2m deep
trench.
Vertical Slinky Trenches
•
Vertically installed slinkies should be
placed in a 300-400mm wide by 2m
deep trench.
Separation Distances
•
Each trench should be separated by a
minimum of 5m between centres
Energy Absorption
•
For every 10m of slinky 1kW of energy can
be absorbed from the ground.
Trench Layout
•
Trenches do not have to be straight, they
can twist and turn as long as the 5m
separation distance is maintained.
Crossing Services
•
Insulate about 1m either side of crossing
point
Unrolling a slinky
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Manifolds
Kensa Supply
An optional expansion vessel can be
fitted to the slinky pipework.
Subterranean manifolds
Electrofusion joints
40 -32mm EF joints
63mm to the heat pump
Above ground manifolds
Compression Joints –
Asymmetrical olives
Pressure testing the slinkies
 Pressure test with water
(generally safer)
 Remove all the air
 Pressure Test to EN805
Section 11.3.3.4 (See
manual)
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Purging the Slinkies
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Antifreeze samples
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 2 independent antifreeze
samples are required by
MCS.
 Taken from the schrader
values an hour apart.
Tested using a
refractometer and
samples returned to Kensa.
 Beware some
refractometers measure
concentration some
measure freezing
temperature
 20% concentration or -10C
protection
Installation of the heat pump
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Installation of the heat pump
Flow to heating system from
heat pump 28 mm OD
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Return from ground 28 mm OD.
Connected via ‘L’ connector with a single
50mm Plasson connection termination.
‘Y’ Connector
Return from heating system to heat pump.
Connected via ‘Y’ connector 28mm OD Speedfit
connection termination.
Supply to ground 28 mm OD. Connected via ‘F’ connector
with a single 50mm Plasson connection termination.
‘L’ Connector
‘F’ Connector
Meter Ready Installations
Pipe Diameter
(mm)
Total length of straight
pipework required in return
pipe (mm)
Total length of straight pipework
required in the flow pipe (mm)
15
300
175
22
440
175
28
560
175
35
700
175
42
840
175
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Electrical Connections
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Simple diagnostics and fault
finding.
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B readings and settings
B01 – Heating Distribution Temperature
B02 – Temperature of water returning from the ground arrays
B03 – Temperature of water going out to ground arrays
B04 – Refrigerant pressure
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Fault Codes
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Fault Codes
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