52
Cleaning the main exchanger module and
combustion unit (see
fi
g. 22)
●
Disconnect the electrical connections of the
electric fan.
●
Disconnect the joint and remove the pipe
linking the gas valve to the injector unit
(venturi).
●
Disconnect the joint and remove the gas
feed pipe from the gas valve.
●
Un-plug the ignition electrode and
fl
ame de-
tection wires from the ignition control unit.
●
Unscrew the ring-nut at the bottom of the
roomsealed chamber and remove the gas
valve.
●
Unscrew the nuts securing the burner unit
(consisting of a fan, manifold and burner) to
the primary heat exchanger.
●
Remove the burner unit, paying particular
attention not to remove the ceramic
fi
bre
protection from the bottom of the heat ex-
changer.
●
Check that the burner is not affected by
deposits, scaling or excessive oxidation.
Check that all the holes in the burner are
free;
●
Clean the electrodes carefully without alter-
ing their positions with respect to the burn-
er;
●
Clean the burner cylinder using a non-metal
brush and without damaging the ceramic
fi
bre;
●
Check the integrity of the washer on the
cover of burner;
●
Clean the heat exchanger (see
fi
g. 23) using
a household detergent for stainless steel,
distributing the product on the spirals of the
exchanger using a brush. Do not wet the
ceramic
fi
bre coating. Wait a few minutes
then remove the deposits using a non-met-
al brush. Then remove the residues under
running water;
●
Remove the pipe clip, remove the conden-
sate drainpipe and clean under running wa-
ter.
●
Unscrew the joint to the condensate trap,
remove the trap and wash under running
water.
●
With the cleaning completed, re-assemble
the components following the above proce-
dure in reverse order.
●
Finally, check the boiler to make sure that all
gas and exhaust joints are tight.
primary heat
exchanger
flue connection
chamber
stainless steel
pipe coil
ceramic fibre
washer
Fig. 2
B
A
Fig. 1
premix burner unit
burner
ionisation
electrode
ignition
electrode
primary heat
exchanger
23
22
