Worcester Gas boiler User Manual

BOILER FUNCTION
6 720 645 222a (2012/05)
17
7.2 BOILER FUNCTION
Fig. 21 Boiler function
NO
YES
MAINS
POWER
SUPPLY
ON
BOILER
DEMAND
Fan to
start
speed.
Pump ON.
IGNITION
SEQUENCE
(see detail)
BLUE
LIGHT
ON
BURNER
LIT?
GREEN
FLAME
LIGHT
ON
Stop spark
and gas.
Wait
10 seconds
5th
attempt?
LOCKOUT
10 second
stabilisation
period.
Fan
modulation
to achieve
set
temperature
(40-82°C)
END OF
BOILER
DEMAND
Gas valve
OFF
Pump run 3
minutes
Fan run 30
seconds
Over temperature shut-
down if water tempera-
ture is 5°C above set
value.
Gas valve OFF.
Fan overrun
30 seconds
3 minute pump
over run
Spark
ignition and gas
4 seconds
NO
YES
Room
thermostat and/or
mains
programmer ON
(or link fitted at
ST10)
AND
Facia mounted
programmer (if
fitted) ON
AND
CH control knob
ON
IGNITION SEQUENCE
6720645222-25.1Wo
Diverter valve
CH position down
Cylinder position up

Worcester Gas boiler Specifications

General

Mounting	Wall-mounted
Brand	Worcester Bosch
Boiler Type	Gas
Fuel Type	Natural Gas
Type	Condensing
Efficiency	Up to 94%
Warranty	Up to 10 years
Heat Exchanger	Stainless Steel
Dimensions	Varies by model
Weight	Varies by model
Control Options	Digital, Smart Thermostats