Glow-worm swift flow 75 Installation Instructions Manual page 10

4.7 Bypass
It is essential that a bypass is fitted in all installations,
22mm o.d. minimum. The bypass must have a lockable
valve "B" in diagram 4.2, incorporated in a position so
that inadvertent closure or unauthorised interference is
not possible.
The bypass MUST be fitted before any system control.
A radiator bypass is NOT recommended.
4.8 Make-up
Provision should be made for replacing water lost from
the system using a make up bottle mounted in a position
higher than the top point of the system, connected
through a non-return valve to the return side of the
heating circuit, see diagram 4.2.
Alternatively, provision for make-up can be made by
pre-pressurisation of the circuit
221129A
4 H e a t i n g S y s t e m
ADDITIONAL
EXPANSION
VESSEL
(if required)
HEATING
CIRCUIT
10
3-LITRE
MAKE-UP
BOTTLE
(if required)
NON-RETURN
VALVE BOILER
AUTO AIR
VENT
MIN. 22mm
DIA. BY-PASS
RETURN
'B'
BY-PASS
'A'
VALVE
FLOW CONTROL
VALVE
DOMESTIC
WATER
FILLING
POINT
DRAIN
POINT
Diagram 4.2