Bosch 15SBI Service Manual download pdf (Page 32)

Does the boiler pump

run?

(removal of pump

venter plug may help

identify rotation of

pump)

Switch off mains

supply.

Remove Molex

connector at X6 and

measure the

resistance across the

red wires. Is the

resistance below

50k ohms?

Is the facia

indicator

still on?

Control was in a lock

out condition.

There are two main

causes for this:

gas/ignition problem

or limit thermostat

tripping.

Continue fault finding

sequence:

Replace the Pump.

(Section 15.4.12)

Check or replace

temperature

sensor or sensor

harness.

Replace control board.

(Section 15.4.9)

The system is not

creating a boiler

demand. Refer to

SYSTEM TEST

Is there 230V AC

across both pins of

connection X5?

Drop down the facia

and expose the three

PCB rear connectors.

Is there 230V at pins

3 & 4 of connector

X11?

(centre connector)

Refer to

above section

Does the fan run and

normal ignition

take place?

BOILER DEMAND TEST

No No

Yes

Set the system to create a boiler demand. Turn facia control knob to maximum.

Does the Fan

run?

Press the facia

reset button.

Does the fan run

after approx

20 seconds?

Is there 230V AC

across both pins

of connector

X4?

Measure the continuity

across the green wires.

Is it open circuit?

Yes

Replace air

pressure switch.

Remove Molex connector at X3

and measure the resistance

across the two wires that run to

the gas valve.

Is the resistance between

3000 and 5000 ohms?

Yes

Replace control board.

(Section 15.4.9)

Yes

Replace gas

valve or cable

to gas valve.

1 2 ... 27 28 29 30 31 32 33 34 35 36 37

Comments to this Manuals

No comments

Bosch 15SBI Service Manual Page 32

Comments to this Manuals

Related products and manuals for Water heaters & boilers Bosch 15SBI