Worcester 28i Junior Specifications download pdf (Page 7)

38

No

No

Reset and restart the

boiler in CH mode.

Does the pump run?

Test resistance across

pins 4 and 5

(blue wires).

Is resistance between

10Ω and 25Ω ?

Repair or

replace

harness.

Remove front panel.

Reset and restart the

boiler. Can a flame be

seen through the spy

glass?

Remove blue

connector from gas

valve. Is there

continuity from blue

wires to multiway

connector?

Replace gas valve

Remove inner cover.

Reset and restart the

boiler. Does a spark

occur across the

electrodes?

Is the boiler fully

water pressurised and

is all air vented?

Rectify fault

Turn off boiler. Remove

the multiway

connector from board

position ST16. Test

resistance across pins

1 and 2 (brown wires)

also pins 8 and 9

(violet).

Is resistance between

60Ω and 100Ω ?

Replace gas valve.

Are the electrodes and

gap and connections

in good order?

Replace

control board.

Remove brown

connector from gas

valve.

Is there continuity

from brown and violet

connectors

to multiway

connector?

Repair or replace

harness.

Repair or replace

spark electrode

or HT leads

Is the gas supply

connected and at the

correct pressure?

Rectify gas supply

problem.

No

No No

No

No No

No

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Replace control board.

If problem not solved

replace gas valve.

Yes

Replace or repair

pump.

Yes

No

TEST D

Test continuity of each

ignition cable.

Yes

No

Replace (both) ignition

cables

Yes

Is there continuity

between pins 6 and 7?

(orange wires to HL

stat)

Replace overheat stat

or wiring to it.

No

Fig. 4. Appliance casing dimensions and

required clearances (side view).

All dimensions in mm

24i 28i

A CH Flow = 70 90

B Relief Valve Discharge = 88 108

C DHW Outlet = 135 155

D Gas = 200 220

E Cold Water Inlet = 265 285

F CH Return = 330 350

Fig. 3. Appliance casing dimensions and

required clearances for installation/servicing

All dimensions in mm

30

158

10

10

7

B

C

D

E

130

24i = 400

102

600

600

203

325

200

200

F

All dimensions in mm

28i = 440

A

Fig. 5. Pipework connections

Unventilated Compartment — for clearances refer to Table 8

Unventilated Compartment — Refer to Table 8

Dimensions

A,B,E,F

18

Minimum system flow rate

Please ensure that the external system flow rate returning to the

appliance is greater than 2 litres/minute.

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