Www.kensaheatpumps.com Ground Loop Design. Heat Sources Horizontal ground loops Collector pipework...
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Transcript of Www.kensaheatpumps.com Ground Loop Design. Heat Sources Horizontal ground loops Collector pipework...
Heat Sources
Horizontal ground loops
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
Most common in commercial buildings
Space efficient
Surface water (closed loop)
o Ideal solution where surface water (eg lake) is available
o Extremely efficient and cost effective
Open loop
Extracts ground water from an underground aquifer
Efficient
Costly
o Ground provides a highly efficient source of heat
o Unaffected by air temperature
o Recharged by solar energy and rainfall
o Ground type (thermal conductivity) needs to be factored into sizing calculations
o Important not to over extract – sizing important
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Ground Loop Design
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/yDHW 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 kW heat Pump at a flow temp of 50C 6
2442
11
1.7
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14650
Kensa Room by room heat loss calculator
6 kW heat Pump at a flow temp of 50C 6
2442
11
1.7
44
Wet Clay
Southwest
From MCS 022
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Property
2 Bed Detached Property
Peak Heat Load 3.5kWAnnual Energy Load 6580kWhDHW annual load = 2578kWh
Underfloor at a flow temperature of 40C (5 stars) SPF 4.1
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9158Kensa Room by room heat loss calculator
4kW heat Pump at a flow temp of 40C 5.1
1796
11
1.7
59
Wet Clay
Southwest
From MCS 022
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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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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 cost-effective to install
SlinkiesHorizontal 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
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Manifolds
Above ground manifolds
Compression Joints – Asymmetrical olives
Subterranean manifoldsElectrofusion joints40 -32mm EF joints63mm to the heat pump
Kensa Supply
An optional expansion vessel can be fitted to the slinky pipework.
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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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Antifreeze samples
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
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Installation of the heat pump
Flow to heating system from heat pump 28 mm OD
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.
Return from ground 28 mm OD. Connected via ‘L’ connector with a single 50mm Plasson connection termination.
‘Y’ Connector
‘F’ Connector
‘L’ Connector
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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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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