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9
Installation
Cold water
from Mains
Balanced Cold
Water Supply
Expansion Vessel
Connection
Cold Water Inlet
Expansion Relief
Valve
Figure 3: Detail Showing the Connection of the
Expansion Vessel to the Inlet Group
If a balanced cold water supply is required a
connection can be taken from the bottom of the
inlet group.
6.1.4 Balanced Cold Water Supply
It is also recommended to install a drain valve
(not supplied) in the lowest point of the cold water
feed to the cylinder. This allows the cylinder to be
drained in a controlled manner should this become
necessary.
6.1.5 Drain Valve
6.2 Hot Water Outlet
The hot water pipe work is to be directly
connected to the hot water outlet connection on
the cylinder.
A thermostatic mixing valve may be required to
limit the outlet temperature. In this case, the
valve should be installed following the
manufacturer’s instructions, ensuring none of the
safety equipment has been isolated, (i.e. make
sure the connection to the thermostatic mixing
valve is taken after the safety equipment of the
inlet group).
6.2.1 Thermostatic Mixing Valve
It is recommended to insulate the hot water pipe
work from the cylinder to the outlets, to reduce
the energy requirements for providing hot water.
It is also recommended to insulate all other
exposed pipework, such as the T&P to the tundish,
thecoilowandreturnandthecoldwaterinlet
pipes.
6.2.2 Pipe Insulation
6.3 Discharge Pipes from Safety Devices
The temperature and pressure relief valve must
be discharged directly or by way of a manifold via
a short length of metal pipe (D1) into a tundish;
and the discharge pipe must be installed in a
continuously downward direction and in a frost
free environment. Water may drip from the
discharge pipe of the pressure relief device and
this pipe must be left open to the atmosphere.
The diameter of discharge pipe (D1) should not be
less than the nominal outlet size of the safety
device, e.g. temperature relief valve.
Where a manifold is used it should be sized to
accept and discharge the total discharge from all
the D1 discharge pipes connected to it.
The discharge pipe work from the expansion relief
valve must be installed constantly falling to an
open point of discharge. It is recommended to
combine it with the discharge of the temperature
and pressure relief valve.
Note: The T&P valve is pre-sealed and if
moved the seal will be broken, should this
occur, it will need to be resealed with an
appropriate sealant (see Figure 13)
6.3.1 Discharge Pipe D1
The tundish should be vertical, located in the
same space as the unvented hot water storage
systemandbettedascloseaspossibleto,and
lower than, the safety device, with no more than
600mm of pipe between the valve outlet and the
tundish.
Discharge should be visible at the tundish, where
discharges may not be apparent, e.g. in dwellings
occupied by people with impaired vision or
mobility, consideration should be given to the
installation of a suitable safety device to warn
when discharge takes place, e.g. electronically
operated.
Note: To comply with the Water Supply
(Water Fittings) Regulations, the tundish
should incorporate a suitable air gap.
6.3.3 Tundish
For a detailed description of the discharge pipe-
work D2 see chapter 6.3.1.
6.3.2 Discharge Pipe D2
It is important that the tundish is positioned away
from any electrical components.
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