Technical information

18
4.5 Bypass
A bypass is not required on the central heating
system unless the system controls could allow
the boiler and pump to operate when there is
no flow.
Where a bypass has to be fitted, the bypass
must be placed at least 1.5 metres away from
the boiler.
4.6 Water Treatment
In the case of an existing installation, it is
ESSENTIAL that prior to installing the new boiler
the system is thoroughly flushed. For optimum
performance after installation of a new system,
the boiler and its associated central heating
system should also be flushed. Flushing should
be carried out in accordance with BS7593: 1992
using a cleanser such as Sentinel X300 or X400,
or Fernox Superfloc.
For long-term corrosion protection, after flushing,
an inhibitor suitable for stainless steel exchangers
should be used, refer to the current issue of BS
5449 and BS 7593 on the use of inhibitors in
central heating systems. Examples are Sentinel
X100 and Fernox.
Flow Rate (litres/hour)
Flow Rate (litres/hour)
Diagram 4.1
12572
Diagram 4.2
12573
Open (vented) system.
Recommended relationship
between pump, cold feed and vent.
22mm (MIN.) VENT
FEED AND EXPANSION
CISTERN
15mm (MIN) COLD FEED
15mm (MIN.) BY-PASS
WITH LOCKSHIELD
VALVE IF REQUIRED
RETURN
FLOW
HEATING
CYLINDER
PUMP
BOILER
150mm
MAX.
1000mm
MIN.
450mm
MIN.
HEIGHT