Grant DuoWave Direct 170, Installation & User'S Instructions

Page: 12 / 32

Secondary Cir
c
uit
Installation
12
4 Secondary Circuit Installation
4.1 Cold Water Inlet Manifold
This manifold contains a pressure
reducing valve (with integral strainer),
double check valve, expansion valve
with a stainless steel seat. The pressure
reducing valve is factory set. The set
pressure is shown on top of the valve.
Maximum inlet pressure to valve is 12
bar.
4.2 Installation
1. Cold water supply to be 22mm
nominal size.
2. Flush supply pipework before
connection to remove all flux and
debris prior to fitting the inlet
controls. Failure to do this may
result in irreparable damage to
the controls and will invalidate
the warranty. Once the pipework
is flushed connect the cold
supply to the Inlet manifold.
3. The manifold can be installed in any
position as long as it is installed in
the correct flow direction. Refer to
the arrows on the side of the body.
Make sure that the head of the
expansion relief valve is offset from
the cylinder for ease of access.
4. The expansion relief valve should be
either horizontal or upright - if fitted
inverted, debris may be deposited
on the seat and cause fouling of the
seat when the valve operates.
Check direction of flow arrows.
5. The black plastic plug in the body is
a pressure gauge connection to
enable pressure monitoring to be
carried out, should the system
develop a fault. It is recommended
that this be accessible.
4.3 Expansion Vessel
A suitable expansion vessel with a pre-
charge pressure of 3bar is supplied for
fitting to all cylinders.
The supplied expansion vessel must be
connected into the cold water supply
between the expansion relief valve (in
the inlet manifold) and the cylinder
using the flexible hose provided.
Flexible hose not supplied with 50 litre
expansion vessel. This vessel to be
connected using rigid pipe. The
expansion vessel must be positioned
with the entry point at the bottom. No
valve should be fitted between the
expansion vessel and cylinder.
The air charge pressure in the
expansion vessel must be regularly
checked (e.g. at every service) and
topped up as necessary. The correct air
charge pressure is 3.0bar.
Refer to Sections 7.1 and 7.5 for further
details.
4.4 Temperature and Pressure
Relief Valve
The temperature and pressure relief
valve (T&P Valve) is supplied factory
fitted to the cylinder. The T&P valve
must not be removed from the cylinder
or tampered with in any way. The valve
is pre-set to lift at 7bar or 90°C and
any attempt to adjust it will invalidate
the warranty.
4.5 Hot Water Supply
1. Connect the hot water supply pipe
to the top outlet (1) of the cylinder.
4.6 Prevention of Scalding
Building Regulations Approved
Document G (Part G3) requires that the
hot water temperature supplied to a
bath should be limited to a maximum of
48°C by using an in-line blending valve
(not supplied with the cylinder) with a
maximum temperature stop. The length
of the supply pipe between the
blending valve and the bath hot water
outlet should be kept to a minimum to
prevent the colonisation of waterborne
pathogens (e.g. legionella). Refer to
Approved Document G for further
details.
6. Expansion relief drain pipework
must be connected to a safe visible
discharge point via a tundish and
the pipework must have a
continuous fall. Connect the
Expansion Relief valve outlet into
the discharge pipe from the
Temperature and Pressure Relief
valve using a 15mm copper pipe
and tee piece (not supplied). Fit the
Tundish below this tee piece using
a short length of copper pipe. Refer
to Sections 4.7, 4.8 and 4.9 for
further information on Tundish and
Discharge pipe.
7. The pressure reducing valve has
two outlets, the second one is for a
balanced cold water supply, to a
shower or a bidet
(over rim type
only, ascending spray type
requires type AA, AB or AD air
gap). Major shower manufacturers
advise fitting a mini expansion
vessel in the balanced cold
supply to accommodate thermal
expansion and prevent tightening
of shower controls. If the
dwelling has a shower mixing
valve (manual or thermostatic) or
a Bidet (over rim type) use the
cold water supply from the
Balanced Cold water connection
on the Inlet Manifold for these
outlets. Do not use the balanced
cold connection to supply bath
taps as this can reduce the flow
of water available to the cylinder.
If the balanced cold water outlet is
not required, blank off the port.
The Benchmark book enclosed with
the cylinder should be completed
after commissioning of the system.
The cylinder must be registered
with Grant UK within 30 days of
installation. Refer to Section 11 for
further details on the Cylinder
Warranty.