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Pressure relief valve
This should be installed between the pressure reducing valve and the Andrews water heater. Should a balanced pressure
cold water draw off supply be required for the cold water outlets, this should be taken off between the pressure reducing
valve and pressure relief valve.
Branches to drinking water outlets should be taken before the pressure relief valve to avoid the possibility of warm
expanded water being drawn from the tap.
Drain valve
It is recommended that the drain valve (supplied) be incorporated into the cold water inlet system, Fig 08, page 17.
It is recommended that the outlet point of the drain pipe work be at least 1 metre below the level of the heater (this
can be achieved by attaching a hose pipe to the drain valve outlet spigot).
Outlet pipework
Ideally the pipework from the cylinder to the outlet fittings should be in 2" BSP 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 design.
Secondary circulation
If a secondary circulation system is required it is recommended that it be connected to the cylinder as shown in Figure
6, Page 18. The secondary return pipe should be in 28mm pipe and incorporate a check valve to prevent backflow.
A suitable WRAS approved circulation pump will be required. On large systems, due to the increase in system water
content, it may be necessary to fit additional expansion volume to the secondary system by fitting an external expansion
vessel to the 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)
35mm o/d = 0.83 litres per metre run (10 litres = 12m)
42mm o/d = 1.23 litres per meter run (10 litres = 8m)
Warnings
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Under no circumstances should the factory fitted temperature / pressure relief valve be removed other than by
authorised Andrews Water Heaters personnel. To do so will invalidate any guarantee or claim.
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The cold water combination valve must be fitted to the mains water supply to the cylinder.
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No control or safety valves should be tampered with or used for any other purposes.
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Water may drip from the discharge pipe of the pressure relief device (expansion valve) and this pipe must be left
open to atmosphere. The discharge pipe should not be blocked or used for any other purpose.
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The tundish must be installed so that it is visible to the end user.
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The tundish, drain valve and motorised valves must be installed away from any electrical components.
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No valve should be fitted between the pressure relief valve and the cylinder.
17
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