Air Supply; Sealed System - Bosch Greenstar ZWBR 7-25 A 23 Installation And Servicing Instructions

8. Air Supply

A separate air supply for combustion is not required.
If the appliance is in a cupboard or compartment then, because
of the low casing losses, it is not necessary to have additional
ventilation for the boiler.
The specified clearances around the appliance must be
maintained to allow the free movement of the air. Refer to
Fig.2,3.
Note: In order to prevent corrosion the air for combustion must not
contain corrosive substances such as solvents, paints, adhesives,
household cleaners etc. The combustion air should be dust free to
reduce the risk of the pre-mix burner becoming blocked.
9. Sealed Systems
The appliance must not be operated without the system being
full of water, properly vented and pressurised.
The expansion vessel has a volume of 10 litres and is charged to
a pressure of 0.75 bar.
The water capacity of the system is shown in Table 9. If a greater
capacity is required then an additional expansion vessel must be
fitted into the system return as close to the appliance as possible.
The system pressure can be set up to a maximum of 1.5 bar with
1 bar being the normal setting.
If the system pressure is greater than 2.5bar when the appliance
is operating at maximum temperature then an additional
expansion vessel must be fitted into the system return as close
to the appliance as possible.
Fig. 6. Sealed primary water system.
Automaticl air vent
Domestic
hot water
Domestic
hot water
Fig. 7. Sealed primary water system – filling method.
Heating
return
APPLIANCE
Refer to Fig.1
Appliance
water flow
diagram
WRC approved
filling loop
Central heating return
Central heating flow
BS stop valve.
Fixed spindle type
Water
main
Non-return Non-return
valve valve
Test
cock
The filling point must be at low level and arranged as shown in
Figs. 6 and 7
The pressure relief valve is set to operate at 3 bar.
There must be no connection to the mains without the approval
of the local water company. All connections in the system must
be capable of withstanding a pressure of up to 3 bar and the
radiator valves conform to the requirements of BS 2767:10.
If Thermostatic Radiator Valves are fitted then it is recommended
that one radiator is left open.
Repeated venting probably indicates a leak and this must be
rectified to ensure the proper operation of the appliance.
No galvanised radiators or pipes must be used.
If any system water treatment is required then only products
suitable for use with Aluminium shall be used i.e Fernox-
Copal or Sentinal X100, in accordance with the
manufacturers instructions. The use of any other substances
will invalidate the guarantee. The pH value of the system
water must be less than 8 or the appliance guarantee will be
invalidated.
A drain cock to BS2879 must be fitted to the lowest point of the
system.
IMPORTANT: Check that no dirt is left in the water pipework
as this could damage the appliance. Thoroughly flush the
heating system and the mains water supply before fitting the
applianceto the
recommendations of BS7593:1992.
A drain cock should be fitted at
the lowest point of the heating
circuit and the appliance
Hose Hose
union union
Temporary hose
7
wall in accordance
Lockshield
valve
Radiator
valve
Test
cock
with the