Technical data

should be flowing through the heat pump or through the other slinkies. The flow rate should be in

excess of 30 litres per minute. This can be checked simply by holding a 10 litre bucket to collect wa-

ter returning from the slinky, and ensuring that it fills in less than 20 seconds. If the flow is less than

this, sufficient velocity is not being achieved to displace the air at the tops of the slinky coils.

v. After water has circulated for about ten minutes, and no more debris has collected in the sieve,

place the return pipe below the water level in the dustbin to ensure all the air has also been

expelled (Fig 24). Stop the purge pump and then the valves on the first slinky can then be closed,

again ensure that the return pipe into the dustbin is secure. At this stage, the valve to the heat

pump should still be closed.

c. Close A

flow

d. Close A

return

Repeat the above procedure (steps iii to v) for the next slinky (i.e. slinky B on the diagram).

vi. When all the slinkies have been purged, the valve to the heat pump can be opened, which will purge

the heat pump of air - this is likely to be very quick, and great care should be taken that the hose

discharging into the dustbin is secure, as any air in the heat pump will be rapidly expelled.

e. Close all valves to the slinky pipes.

f. Open V1

vii. Continue purging the heat pump until all the air has been expelled. (No more bubbles are expelled

from the return pipe. Fig 24)

viii. After the air has been removed it is advisable that before the antifreeze is added the system is leak

tested at 5 bar for 15 mins. (See 5.1.2.1)

Fig 23 Purging the

Slinkies of Air

Fig 24 Slinkies

Purged of Air

5.1.2 Adding Antifreeze for Multiple Slinkies

The antifreeze provides protection to the heat pump by preventing the circulating ground fluid from

freezing in the heat exchanger. If not added in sufficient quantities the heat pump can freeze and cease

working. All antifreeze provided with the order should be added and it is recommended that the quantity

is roughly divided between the number of slinkies. This amount of antifreeze is the minimum required for

a standard system. If the heat pump and manifold are a distance apart this quantity may need to be in-

creased. Please contact Vent-Axia for further details.

It is very important to purge all the air from the system before adding the antifreeze as it is very difficult

to remove the air with the antifreeze in the system due to the higher viscosity of the mixture.

Once the purging of all the air within the slinkies and heat pump has been completed the antifreeze needs

to be added.

i. Open the flow and return valves to one of the slinkies and with the purge pump running, empty

some of the water out of the dustbin via the return pipe to the dustbin. This is fresh water and

hence can be discharged to drain. The level needs to drop to about 200 to 250mm. Take care that

the suction pipe remains covered with water to stop any air being admitted into the system.

ii. Turn the purge pump off and close both the flow and return valves on the slinky.

iii. Carefully pour a drum of antifreeze into the dustbin using appropriate handling protection as out-

lined in the COSHH (Section 8). Allow the solution to settle for a few moments to allow any trapped

air to escape.