Ferroli Primary Heat Exchanger 24 kW 39820420

The Ferroli 39820420 is a primary heat exchanger for gas boilers in the Diva, Divatech and Divatop ranges. It sits in the combustion circuit and transfers heat from the burner into the heating and domestic hot water water paths. The unit is a clip-fit assembly measuring 225 mm along the working length and 180 mm across the working width.

• The boiler fires but the heating circuit or hot water stays cold, or warms unevenly across the radiators.
• Repeated lockouts or ignition faults that clear only after the appliance cools.
• Kettling, banging or gurgling noises from the heat exchanger during operation.
• Water weeping from the exchanger body, its seals or the clip joints.
• Discoloured or blackened water when the system is drained, or visible scale and debris blocking the waterways.

• Confirm the appliance model and serial number against the compatibility list, as the same boiler name can appear with different product codes.
• Check whether the existing part carries the earlier number 37404080, which this exchanger replaces on the listed models.
• Confirm that the paronite gaskets and metal clips supplied with this exchanger match the connections on the appliance being repaired.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.