Www.kensaheatpumps.com Ground Loop Design. Heat Sources Horizontal ground loops Collector pipework...

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Ground Loop Design

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


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.


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)


14650

Kensa Room by room heat loss calculator

6 kW heat Pump at a flow temp of 50C 6

2442

11

1.7


Look up extraction tables


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


3.4 From Heat Emitter Guide

4235.3

96.25

5

481.3

500


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


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


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



3856

65.36

5

326.8

400


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


Unrolling a slinky


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.


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)


Purging the Slinkies


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

Installation of the heat pump


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


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


Electrical Connections


Simple diagnostics and fault finding.


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


Fault Codes

Www.kensaheatpumps.com Ground Loop Design. Heat Sources Horizontal ground loops Collector pipework...

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