Bosch Worchester GREENSTAR ZWB 7-27 HE combi Installation And Servicing Instructions page 46

Pump ON Fan to
Diverter valve start speed.
operates. Gas valve opens.
Pre-heat satisfied.
Burner remains OFF
until flow temperature
is below set value.
Mains Green Hot
Pre-heat
switch light water
mode.**
ON. ON. demand.
Ignition sequence
Ignition spark for
5 seconds.
Repeats 5 times
before lock-out.
Ignition
spark
Ignition sequence
5 secs
Burner shut-down if
primary temperature
Burner lights.
exceeds 94 °C remains
Red light ON.
OFF until 78 °C
Over temperature
shut-down if water
Gas valve shuts.
Pump remains ON. temperature is 8°C
above set value.
.
Pump ON Fan to
Diverter valve start speed.
operates. Gas valve opens.
Yes
Burner lights.
Red light ON.
No
Fan runs to purge
gas from burner.
** NOTE:
The appliance controls can be set to one of
2 modes of operation.
1. "Comfort" mode -
Full pre-heat
2. "ECO" mode -
a) Operates as an instantaneous combination
boiler.
b) Demand Detection: a short demand (less
than 5 seconds) switches the control to
"Comfort" mode for 5 mins. Mini pre-heat.
The Factory setting is "Comfort" mode.
Heat input
Gas valve
modulates to
Demand
maintain the
ends. Red light
delivery
temperature.
6 720 610 576 - 24.1O
Fan runs for
closes. upto 3 mins. Pre-heat
Pump runs mode.**
OFF. for 30secs.