System Control; Treatment Of Water Circulating Systems; Showers; Expansion Vessel (Ch Only) - Baxi COMBI 224 Installation And Service Manual

5 Before installation
26

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.

5.2.6 Treatment of water circulating systems

All recirculatory water systems will be subject to corrosion unless they are
flushed and an appropriate water treatment is applied. To prevent this, fol­
low the guidelines given in BS 7593 Treatment of Water in Domestic Hot
Water Central Heating Systems and the treatment manufacturers instruc­
tions.
Treatment must involve the use of a proprietary cleanser, such as Sentinel
X300 or X400, or Fernox F3 and an inhibitor such as Sentinel X100 or Fer­
nox MB-1.
Full instructions are supplied with the products. For further information
contact Sentinel (0800 389 4670) or Fernox (0870 870 0362).
Note
Failure to flush and add inhibitor to the system will invalidate the
appliance warranty.
It is important to check the inhibitor concentration after installation, system
modification and at every service in accordance with the inhibitor manufac­
turer's instructions. (Test kits are available from inhibitor stockists.)
Complete the label supplied with the inhibitor and attach to the inside of
the boiler case. Detail of system treatment should be added for future ref­
erence.
For information or advice regarding any of the above contact Baxi Custom­
er Support 0344 871 1545.

5.2.7 Showers

If a shower control is supplied from the appliance it should be of the ther­
mostatic or pressure balanced type. Thermostatic type shower valves pro­
vide the best comfort and guard against water at too high a temperature.
Existing controls may not be suitable - refer to the shower valve manufac­
turer.

5.2.8 Expansion vessel (CH only)

The appliance expansion vessel is pre-charged to 1.0 bar. Therefore, the
minimum cold fill pressure is 1.0 bar. The vessel is suitable for correct op­
eration for system capacities up to 120 litres. For greater system capaci­
ties an additional expansion vessel must be fitted.
For GB refer to BS 7074 Pt 1. For IE, the current edition of IS 813 Domes­
tic Gas Installations.
Checking the charge pressure of the vessel - to check the charge accu­
rately ensure the system is cold. It is also necessary to relieve the pres­
sure by draining the boiler. Using a suitable gauge check the pressure at
the valve on the underside of the vessel. Adjust the pressure as required
and repressurise the system.
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