h)
Remove the bracket V by unscr
ewing the screws that hold it to
the chassis.
i)
Rotate the heat exchanger as indicated by the ar
row and
remove it towards the front of the boiler.
j)
Remove the clip X and the pipe H.
k)
Reassemble the heat exchanger car
rying out the removal
operations in reverse order.
After r
eassembling ensure that the fan-exchanger and
exchanger-elbow gaskets are correctly mounted and
ensure a good sealing.
29
W
arning: After cleaning or replacement, if it
is deemed necessary to undertake a
combustion analysis, refer to section 6.1.
!
9.4
FAN & AIR PRESSURE SWITCH
Refer to Figur
e 35
a)
Remove all the Casing panels and the combustion chamber
lid as section 6.2.
b)
Disconnect the spade connectors fr
om the fan and measure the
electrical resistance of the motor which should be approx. 25
Ω
(at room temperature).
c)
Disconnect the air pr
essure switch sensing pipe from the fan.
d)
Remove the fan assembly by twisting counter
clockwise and
withdraw the assembly by gently easing from the condensing heat
exchanger.
e)
Check the
Air pr
essure switch
operation
f)
Disconnect the wir
es and check the electrical resistance
between the connections of the Air pressure switch. The contacts
should be open.
IMPOR
TANT: Ensure gas is turned OFF before
proceeding with the next step.
g)
Run the boiler (the Fan must r
un) and check the electric
resistance between the connections. The contacts should be
closed.
h)
Fit the new fan assembly and r
e-assemble in reverse order.
i)
Ensur
e that all joints and seals are correctly re-fitted. (Polarity
is immaterial on the fan connections.)
9.5
BURNER
9.7
GAS VALVE
Refer to Section 6.3 and Figur
es 28 and 29.
Refer to Section 6.3 and Figure 30.
ELECTRODES
9.6
IGNITION & DETECTION
Refer to Figur
e 36
a)
Remove the Casing panels and the combustion chamber lid
(see section 6.2).
b)
Disconnect the connectors a and b (Fig. 36).
c)
T
urn off the gas supply and disconnect the gas supply pipe
from the inlet pipe c to the gas valve.
d)
Unscr
ew the retaining nut d from the inlet pipe.
e)
Unscr
ew the nut to the burner rail e and remove the whole
gas valve assembly.
f)
Unscr
ew the screws f and remove the pipes to the valve.
g)
Reassemble the valve car
rying out the removal operations in
reverse order, ensuring the 2 gaskets are fitted to the valve.
After any service operation, turn on the gas supply at the gas
service cock and check for gas soundness.
Please note, the gas valve self calibrates
every 5 burner starts to ensure optimum
performance and correct burner pressures.
!
35
36
