Bosch Worchester GREENSTAR ZWB 7-27 HE combi Installation And Servicing Instructions page 37

Expansion vessel
The expansion vessel should be checked once a year.
B Depressurise appliance.
B If necessary, adjust expansion vessel charge pres-
sure to static head of the heating system.
Heating system pressure
Fill the system using the WRc approved
i
filling loop.
B The pointer on the pressure gauge should be 1 bar.
B If the pointer is below 1 bar (when the system is
cold), water should be added until the pointer is
1 bar again.
B Max. pressure of 2.5 bar when the heating system
water is at maximum temperature must not be
exceeded. If this pressure is exceeded then an extra
expansion vessel must be fitted in the system return
as close to the appliance as possible.
B If the system does not retain the pressure, the expan-
sion vessel and the heating system should be
checked for leaks.
Electrical wiring
B Check the electrical wiring for physical damage and
replace any damaged wires.
6 720 610 576 GB (02.05)
Maintenance
37