Electric fan (see fig. 1)
• Remove and dismantle the entire burner unit (see
“Cleaning the burner unit”).
• Use an 8 mm wrench to unscrew the four nuts
securing the electric fan to the gas manifold and then
remove the electric fan, noting the positions of the
washer.
• Remove the air intake duct, unscrew the two fixing
screws from the venturi and remove the electric fan,
paying particular attention not to damage the cork
gasket.
• Replace the electric fan and re-assemble the
components following the above procedure in reverse
order.
• Switch on the electricity, water and gas supplies and
check the soundness of the joint by measuring the CO
2
levels;
D.H.W heat exchanger (see fig. 2)
•
Close the shut-off valve and drain the domestic hot
water circuit and central heating circuit of the water
heater.
• Disconnect the joints securing the heat exchanger to
the pipes.
• Unscrew the screws joining heat exchanger fixing
bracket to its support and remove it.
• Remove the heat exchanger.
• Fit new washers.
• Replace the heat exchanger and re-assemble the
components following the above procedure in reverse
order.
• Switch on the electricity, water and gas supplies, fill the
system with water and check for any leaks from the
joints.
Circulating pump
(motor body) (see fig. 3)
• Close the shut-off valves and drain the central heating
circuit of the water heater;
• Use a 5 mm Allen key to unscrew the four screws
securing the motor body to the impeller body;
• Remove the motor body and check the condition of the
washer. If necessary, replace the washer;
• Replace the circulation pump and re-assemble the
components following the above procedure in reverse
order;
• Switch on the electricity, water and gas supplies and fill
the system with water. Check for any leaks from the
joints and bleed off any air from the circuit. Restart the
water heater.
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