12. Air / gas manifold and fan
assembly
Isolate the gas and electrical supplies.
Remove electrical connector from fan.
Remove wire clip from gas valve outlet then
pull gas adjustment assembly free from plastic
connector and pull clear of case. See 6.1.
12.1
Undo and remove securing nut (A) from the
top of the heat exchanger.
12.2 *
Remove retaining plate (B).
12.3
Rotate fan and air/gas manifold assembly
(shaded) around the top of the heat
exchanger until the lug on the air/gas
manifold is visible.
Lift up assembly and remove from boiler.
NOTE:
After re-assembly, check CO/CO
2
levels as described in the setting of the
air/gas ratio section.
13. Pressure switch
13.1
Remove electrical connections (C).
13.2
Slacken top retaining screw and remove
bottom screw. (D).
13.3
Remove tube (E).
13.4
Remove 2 screws (F) retaining pressure
switch to bracket.
Refit new pressure switch to bracket.
NOTE:
After re-assembly, check CO/CO
2
levels as described in the setting of the
air/gas ratio section.
REPLACEMENT OF PARTS
The following components require
the air / gas manifold and fan
assembly to be removed:
Pressure switch
Fan
Electrode assembly
Burner
Heat exchanger
12.1
12.2
13.4
13.3
13.2
13.1
A
B
C
D
E
F
12.3
I M P ORTANT:
E N S U R E TU B E I S
REFITTED TO PRESSURE SWITCH
I M P ORTANT:
I F TH E JOI NT
BETWEEN THE AIR/GAS MANIFOLD
AN D TH E H EAT E XCHANG E R I S
DISTURBED THE SEALING GASKET
MUST BE REPLACED.
IMPORTANT:
AFTE R R E-ASS E M B LY TH E COM-
B USTION M UST B E CH ECK E D
USING THE PROCEDURE IN THE
SECTION “SETTING THE AIR/GAS
RATIO”. MEASUREMENT AND SET-
TI NG OF TH E GAS RATIO M UST
NOT BE ATTEMPTED UNLESS THE
P E R SON I S EQU I P P E D W ITH A
C OM B USTION ANALYS E R C ON-
FORMING TO BS 7927 AND IS COM-
PETENT IN ITS USE.
REPLACEMENT OF PARTS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR Ri
8 716 115 168a (06/2008)
44
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