Worcester 350 Combi User Manual

NO
'fum the domestic hot water tap to ----. Have the STANDBY and DEMAND
maximum. Once lit, does th e burner indicators gone out ?
stay alight '
YES
NO
Remove the Molex plug from terminal ----.
X13 . is there a resistance of 1.5 to 25
kohms across both black pins ?
YES
NO
Replace the domestic hot water
sensor.
I
1----------- System overheat thermostat has
activated. Reset the thermostat and
bleed any air from the system. Repeat
test Does the burner stay alight?
Remove and inspect the domestic hot ----. Replace the driver board assembly .
water sensor. Is it badly scaled up ?
Is it possible to slightly reduce the
domestic hot water flow raie so that NO
the gas pressure reduces and settles, ----.
and the hot water t emperature
stabilises at 55·65'C
YES
NO
Slowly reduce the domestic hot water ----.
flow so that the burner eve n tually
shuts down. Does the boiler
successfully relight when the tap is
immediately fully opened again ?
YES
1\Jm off the tap . Does the boiler
shutdown immediately?
I YES
NO
----.
I NO
Reset the thermostat.
NO
Does the voltage on the wh ite pin of ----------...1
terminal XS increase as the flow rate
reduces ?
---------------- Replace t he gas valve
------ - YES
NO
A lockout condition has occurre d ----. Use the potentiometer RV2 on the
driver board to reduce the domestic
hot water temperature. Repeat the
t est If a lockout occurs again then
replace the domesti c hot water sensor.
because the domestic hot wa t er
thermostat has activated to shut off
the gas valve . Note . This ap plies only
if the domestic hot water thermostat
is wired in series with the gas valve.
Replace the flow switch .
f YES
NO NO
Switch off the electrical mains supply. ----. Replace the flow switch. Also measure ----. Also replace the driver board assembly.
Remove the connector from terminal the resistance between the top pin of
X1 and measure the resistance terminal X1 on the driver board and
across the blue and brown pins . Is it neutraL Is it 3-5 kohms ?
End of domesti c hot water test
Remove the manometer. Reset
app li ance controls.
an open drcuit? I
.... •--------------' YES
40

Worcester 350 Combi Specifications

General

Brand	Worcester
Model	350 Combi
Category	Boiler
Language	English