Operational Flow Diagrams - Worcester Highflow 400 BF Installation And Servicing Instructions

16. Operational Flow Diagrams

230V
mains
supply to the
boiler.
Frost thermostat and CH
control knob ON
Room thermostat ON
Green
CH programme ON
power
light ON.
CH temperature control
(NO HW demand)
(NO TANK demand)
230V
mains
supply to the
boiler .
Green
power
light ON.
HW
temperature
HW
control ON.
light ON.
Pump ON.
AND
HW flow above
2.7 l/min.
CENTRAL HEATING MODE
3 minute wait
AND
CH
temperature
4°C below
set point.
OR
(or link)
AND
CENTRAL
HEATING
(or link)
DEMAND
AND
ON
DOMESTIC HOT WATER MODE
Gas valve
OFF.
HW programmer ON
(or link)
AND
HW flow above 9 l/min &
HW temperature lower
than set point
OR
HW flow below 9 l/min &
HW temperature
4°C below
set point.
Gas valve OFF.
CH light ON.
Pump ON.
Diverter valve
ON.
CH light ON.
Minimum
Pump ON.
heat input for
Diverter valve
20 seconds
ON.
then ramp up
Ignition
over next
Sequence
minute.
at minimum
heat input.
DHW clock OFF
OR
DHW temperature 6C
above set point
OR
DHW flow below 3.9
litres & DHW
temperature
above set point.
Modulate heat
Ignition
sequence at
temperature
minimum heat
set by user
input.
Modulate heat
input if the
flow is above 9
l/min.
temperature
Minimum heat
input for 30
seconds if the
flow is below
9 l/min.
34
CH
temperature
5°C above set
point.
Modulate
heat input to
maintain set
point set by
user
control
(50-82°C).
Pump continue for
Pump pulse for 3 seconds if
primary temperature is
above 82°C.
input to
Flow
maintain
less than
2 l/min.
control
( 55-75°).
65% heat
input if
primary
above
84°C.
DEMAND
END
Pump and
diverter
valve
energised for
3 minutes.
OVERRUN
MODE
3 seconds.
Tank 7°C
above
set point.
Tank 7°C
below
set point.
TANK
MODE