Strebel S-CB Px 120, Installation Operating & Maintenance Manual

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S-CB Px 120 Manual 21
6.14. Water pressure
First and for all, the installation should be designed and built conform all applicable regulations and standards,
including the right safety valves.
IMPORTANT: Always keep the pressure in the boiler lower than the value at which its safety valve opens.
Sensor
A water pressure sensor has been built into the boiler. With this sensor, the minimum water pressure in the boiler
is 0,8 bar and the maximum pressure is up to 4,0 bar (sensor values). The normal water pressure is supposed to
be between 1,5 and 2,0 bar.
The pressure sensor will stop the boiler from firing when the water pressure drops below 0.8 bar, and start the
boiler firing again when the water pressure reaches above the 1.0 bar. These values can be changed in the boiler
control settings.
Higher pressure systems (e.g. in high buildings)
If pressures higher than 4,0 bar occur in the heating system, the best solution is to separate the system from the
boiler by means of a plate heat exchanger. Now the boiler pressure can still be under 4,0 bar and the boiler con-
trol remains as described above.
Without plate heat exchanger, above 4,0 bar, a water pressure switch has to be built into the boiler instead of the
water pressure sensor - the maximum allowed value in the boiler now is 6,0 bar and the boiler control needs to be
adjusted.
6.15. Chemical water treatment
The chemical compatibility of several products for treatment of the central heating equipment has been tested on
the heat exchangers and the boilers. A list of corrosion inhibitors in preventative and curative treatment for gas
fired central heating boilers can be supplied by the manufacturer.
6.16. Under floor heating
When using an under floor heating system, the boiler circuit must be separated from the heating circuit with a
plate heat exchanger.
6.17. Flush the system with fresh water
The water of the boiler and heating circuit should be free of any particles, debris and pollution. Therefore the
complete installation must always be thoroughly flushed with clean water before installing and using the boiler(s).