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13
Commissioning
6.6 Connection of Secondary Return
For cylinders that do not have a dedicated
secondary return connection, it is possible to
install a secondary return by connecting a
swept - T to the cold water inlet of the cylinder
(see Figure 10).
The secondary return pipe should incorporate a
check valve and a WRAS approved
circulation pump; timer and thermostat to be
provided separately. Where secondary return
circuits are used, then an additional expansion
vessel may be required.
The secondary return loop must avoid:
- stagnant water in long pipe runs
- undue water wastage
To minimise the energy consumption of the
secondary return circuit and to ensure reliable
operation it is important to consider:
- the control of the circulation pump to be time
and temperature controlled.
- the secondary return circuit pipework to be
insulated.
- the secondary return pump to be of suitable
HW Outlet
To Taps
From Taps
Swept-T
Figure 10: Secondary Return Loop
7 Commissioning
At the time of commissioning, complete all
relevant sections of the Benchmark Checklist
located on the inside back pages of this
document.
The following commissioning procedures only
detail the required steps to be taken for the
potable water loop:
1) Before making any mains connections to
pipework out to ensure all debris has been
removed so as not to damage the strainer
within the combination valve.
combination valve and check all
connections and joints to ensure they have
been tightened and secured correctly.
3) Before turning on the mains supply to the
cylinder a hot water tap should be opened,
below where the cylinder is located.
4) Check the pre-charge in the expansion
vessel and ensure it is at least 3 bar. Note
actual pressure on label on expansion
vessel.
until water runs from the open hot water
debris has been removed.
6) Close the hot water tap.
7) Check all joints for leaks, even those not
having been altered especially when
replacing a vented cylinder.
8) Open temperature and pressure relief valve
to ensure proper discharge and check after
closing that valve is not dripping.
9) Open expansion relief valve to ensure
proper discharge and check after closing
that valve is not dripping.
10) Check all shower outlets, toilet cisterns and
(especially when replacing a vented unit).
Open all water outlets to purge air from
pipework and ensure proper operation.
11) Instruct user in the operation of the unit
and hand over this manual advising the
owner of annual service requirements.
12) Complete the technical data label on the
cylinder with legible and permanent
writing.
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