1.6 Water
Supply
M
ains Supply Requirements
It is essential that the mains supply pressure and
available flow rate are capable of meeting demand for
both hot and cold water
P
romax Store is not
recommended for unvented use where the dynamic
mains pressure is below
1
.0 bar.
Unless consistently high mains pressures are available,
it is unli
k
ely that a service pipe of less than 2
5
mm OD
(Blue MD
P
E) will supply an adequate flow rate.
Plumbing Design
A combination inlet valve group is included with every
P
romax Store (pac
k
ed in the “Accessories” box
supplied with the Heat Engine). The mains water supply
must be connected via the combination reducing valve
and the cross fitting, in that order. Both components are
clearly mar
k
ed with the direction of flow (see Fig.
11
page 23).
The cold feed pipe to showers (and other mixer fittings
needing balanced pressures) must be ta
k
en from the
22mm blan
k
ed outlet port of the combination reducing
valve (or a tee between this and the cross fitting). The
valve can be sited near where the water mains enters
the dwelling, to assist with providing reduced pressure
to all the system.
C
old water draw-offs that do not require a balanced
supply e.g. hose-union or W
C
cistern, should be teed
off upstream of the combination reducing valve.
A 22mm connection is provided from the hot water
store. Smaller diameter pipewor
k
may be used locally
for terminal fittings as part of a balanced design.
Thermostatic shower mixers are recommended to
optimise performance; these must be suitable for use at
mains pressure. Using flow restrictors will help prolong
the showering time available from smaller capacity
stores.
Use in Hard Water Areas
In the UK., water is drawn from diverse sources some
of which have high levels of natural hardness. If not
dealt with effectively, the scaling associated with hard
waters can adversely affect hot water performance. As
a general guide, if the temporary hardness exceeds 200
mg/l, then some form of water treatment device is
required. The ultimate solution is an ion-exchange (salt
regenerated) water softener. In addition to protecting
the
P
romax heat exchanger against the effects of
limescale, an ion-exchange softener offers users other
benefits and should be specified with an appropriate
flow rate capacity.
Water “conditioning” devices such as those which dose
the incoming water with food grade polyphosphates can
be effective in reducing limescale but require correct
siting and regular replenishment to remain operational.
They should generally not be fitted where heat could
impair their performance. Other types of device can
inhibit scale formation but their effectiveness may vary.
The manufacturers of any water conditioning device
should be consulted regarding its suitability for the
application and the particular water supply to the
installation address.
Record the type of conditioner being used in
“Benchmar
k
”
C
ommissioning
C
hec
k
list.
Treatment of Water Circulating Systems
All recirculatory water systems will be subject to
corrosion unless an appropriate water treatment is
applied. This means that the efficiency of the system will
deteriorate as corrosion sludge accumulates within the
system, ris
k
ing damage to pump and valves, boiler noise
and circulation problems.
When fitting new systems flux will be evident within the
system, which can lead to damage of system
components.
All systems must be thoroughly drained and flushed out.
Using, for example Sentinel
X
300 or
X
400 or Fernox F3.
They should be used following the flushing agent
manufacturers instructions.
System additives - corrosion inhibitors and flushing
agents/descalers should comply to BS
75
93
requirements, e.g Sentinel
X1
00 and Fernox MB-
1
which
should be used following the inhibitor manufacturers
instructions.
Full instructions are supplied with the products, for
further information contact Sentinel (0
8
00 3
8
9 46
7
0) or
Fernox (0
87
0
87
0 0362)
Failure to flush and add inhibitor to the system will
invalidate the appliance warranty.
It is important to chec
k
the inhibitor concentration after
installation, system modification and at every service in
accordance with the manufacturers instructions. (Test
k
its are available from inhibitor stoc
k
ists.)
Sealed Primary Systems
This boiler must be installed into a sealed primary
system. As a general guide systems of up to
7
-9
radiators will operate satisfactorily with the
1
0 litre
expansion vessel built into the boiler.
•
Guidance on expansion vessel sizing
These notes explain how to calculate the total
expansion vessel volume required, based on the size
and the initial cold fill pressure of the system. If the
required volume exceeds that of the vessel fitted to
the boiler then an additional vessel should be
installed, on the return connection from the heating
system. The charge pressure of any additional vessel
is assumed to be
1
.0 bar, the same as the vessel
fitted to the boiler.
17
© Baxi Heating UK Ltd 2015