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An inline filter (open vented) and an effective scale prevention device must be fitted to the cold feed inline
before the feed reaches the unit.
6.5 Cold Water Combination Valve
The Cold Water Combination Valve must be sited close enough to the unit to allow the safety
discharge pipe to run in to the tundish, in line with appropriate Regulations. The
expansion (safety valve) must not be used for any other purposes.
Under no circumstances is the expansion vessel to be connected to the balanced cold outlet on
the combination group valve.
The Cold Water Combination Valve can be installed as a complete one piece unit. The valve incorporates a
factory set, non-adjustable Pressure Reducer/ Strainer, an Expansion Valve connection a single Check
Valve and balanced cold feed. The valve can be fitted in any orientation to suit the installation, however,
ensure that the valve is installed with the direction of flow arrows (stamped on the side of the brass body)
pointing towards the unit (in the direction of the flow of water).
If a balanced pressure cold water supply is required for a thermostatic shower mixer valve this
must be supplied from the cold water balance outlet (see above). Branches to drinking water
outlets should be taken before the combination group valve to avoid the possibility of warm
expanded water being drawn from the tap.
6.6 Drain-Cock
The unit is fitted with a drain-cock and this is used for draining down the unit. You must ensure
that this is accessible and that a hosepipe can be easily attached to allow water from the unit to
be drained down.
6.7 Outlet Pipe Work
Ideally, the pipe work from the unit’s outlet fittings should be in 22mm pipe with short runs of 15mm pipe
to showers and basin taps. Small bore pipe can also be used to suit some taps, but runs should be of
minimum length. Pipe sizes may vary due to system particulars.
6.8 Secondary Circulation of Hot Water
If a secondary circulation system is required, it should be
installed as per Figure 6. The secondary return pipe should be in
15mm pipe and incorporate a check valve to prevent backflow. A
suitable WRAS approved bronze circulation pump will be
required with appropriate unions. On large systems, due to the
increase in system water content, it may be necessary to fit
additional expansion volume to the system by
fitting an external expansion vessel to the secondary circuit. This
should be done if the capacity of the secondary circuit exceeds
10 litres.
Pipe capacities (copper):
15mm o/d = 0.13 litres per metre run (10 litres = 77m)
22mm o/d = 0.38 litres per metre run (10 litres = 26m)
28mm o/d = 0.55 litres per metre run (10 litres = 18m)
