Bosch Appliances 12/18, 18/25, 25/32kW Base of the control box before replacing any components

Boiler not operating with a heating / hot water demand

Replace

control box

	Yes
230V at			Replace
solenoid coil
		No
			pump
in purge?

Replace

lead

		Photo cell
	No				Yes
		lead OK?
			Yes
Disconnect photo cell,
reset lockout, burner
				No
lights then locks out?

Stray light

on photo

cell?

No

Replace

photo cell

Replace coil

lead

No

Coil lead

OK?

	Replace
Yes
	control box

These fault finding charts locate and rectify faults. correct and complete we Worcester, Bosch Group to be competent.

INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR HEATSLAVE EXTERNAL 12/18-18/25-25/32 8 716 106 252b (07/06

FAULT FINDING

Yes

Yes

No

Burner

Yes

Burner

No

Lockout

No

Pump

Yes

Spark

Yes

Lockout

No

Nozzle

No

230V at

Yes

2.2kΩ

No

Replace

within 1

produces

after purge

atomising

solenoid

motor runs?

lights

produced?

across

solenoid coil

second?

pressure?

before oil

fuel?

coil?

immediately

solenoid

motor runs?

solenoid

Yes

coil?

opens?

Yes

No

No

Combustion

Reset air

Yes

No

air setting

No

setting

Drive

correct?

Replace

Solenoid

Replace

coupling

Yes

No

control box

operating?

pump

broken?

230V at

Transformer

No

No

Combustion

Reset

Yes

transformer?

lead OK?

head set

No

combustion

Control box

Motor or

Replace

Oil to

Yes

Yes

correctly?

head

Pipe to

Yes

pump

Yes

motor/

Yes

nozzle

locks out?

pump?

seized?

pump

Electrodes

holder OK?

Replace

No

No

Yes

& leads

Flame off

Yes

control box

Boiler or

OK?

and

No

flue blocked

Check

Yes

re-lights?

Oil check

Replace oil

L & N to

230V at

Replace oil

No

connections/

Yes

valve OK?

No

check valve

control box?

motor?

pump

replace leads

(if fitted)

(if fitted)

Replace

No

Yes

Yes

transformer

If BF

remove

Check boiler

Motor 40Ω

Replace

burner

Reseal BF

Replace

controls &

across

No

snorkle tube

Yes

on

motor

nozzle

supply

L & N?

& retest.

reposition

Yes

Lights OK?

No

Replace

Replace

motor

Yes

Photo cell

control box

capacitor

functional?

Note: This chart assumes all wiring within the control box base is correct, if in doubt check the wiring against the diagram on

No

the base of the control box before replacing any components.

All resistance measurements are actual measured values and some variation is to be expected, therefore measured values

should be similar to but not necessarily identical to the given values.

Replace

Measure all 230V tests between

The operation of the photo cell can be tested by measuring the resistance across the photo cell, it should be a high resistance

photo cell

Neutral (N) and the pin, wire or

(greater than 10MΩ or open circuit) in the dark and low resistance (15kΩ or less) in light.

terminal specified.

Burners on balanced flue systems can recirculate flue products resulting in the burner cycling, if this happens check the flue

system integrity and the terminal position.

Whilst every effort has been taken to ensure the information given is cannot guarantee that every eventuality has been covered. cannot be held responsible for costs incurred by persons not deemed	are provided to assist competent and suitably qualified engineers to
SATRONIC CONTROL BOX	FAULT FINDING LOGIC FOR

46

FAULT FINDING

& DIAGRAMS