Hard Water Area; Bypass; System Control; Treatment Of Water Circulating Systems - Baxi 424 Combi 2 Installation And Service Manual

Important
Any wiring to the boiler, from either the mains or an external
control, MUST be cable of the following specification:- 0.75mm
3183/4/5Y (depending on installation) multi strand flexible cable
conforming to BS 50525-2-11. Cable of the above specification
is sufficiently flexible to with-stand normal regular opening and
closing of the facia/control box as expected during routine
servicing and other maintenance work. Use ONLY cable glands
supplied with the boiler, or provided as spares by the
manufacturer. Under no circumstances must solid core cable be
used as it is not intended for applications where movement may
occur. The use of solid core cable could result in situations
potentially haz-ardous to health. These points must be
considered when initially wiring the boiler to the installation, and
if replacing any wiring during the service life of the boiler.
5.2.3

Hard water area

Important Only water that has NOT been artificially softened
must be used when filling or re-pressurising the primary system.
If the mains cold water to the property is fitted with an artificial
softening/treatment device the source utilised to fill or re-
pressurise the system must be upstream of such a device.
5.2.4

Bypass

The boiler utilises the primary side of the DHW plate heat exchanger as an
automatic integral bypass.
5.2.5

System control

Further external controls (e.g. room thermostat sensors) MUST be fitted to
optimise the economical operation of the boiler in accordance with Part L
of the Building Regulations. A range of optional controls is available. Full
details are contained in the relevant Sales Literature.
Any proprietary OpenTherm control MUST allow individual adjustment of
CH and DHW temperature.
5.2.6

Treatment of water circulating systems

All recirculatory water systems will be subject to corrosion unless an ap-
propriate water treatment is applied. This means that the efficiency of the
system will deteriorate as corrosion sludge accumulates within the system,
risking 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.
BS 7593 gives extensive recommendations on system cleansing and wa-
ter treatment.
All systems must be thoroughly drained and flushed out using appropriate
proprietary flushing agent.
A suitable inhibitor must then be added to the system.
All system additives (flushing agents, cleansers, inhibitors etc.) must com-
ply with the requirements of BS 7593. Full instructions are supplied with
the products and for further information contact the additive manufacturer
directly or consult their website.
5 Before installation
Combi 2 23