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13.5 Combustion fans
The XXL boiler have 4 up to 6 Fans, depending on the boiler size.
All the fan can be controlled indpendet The address and Fan no. is always the same, as indicated below.
Primary fan, blows the air to the combustion trough the fire grate, in different zones, how many zone,
depend on the boiler size.
The secondary fan, supplies all the air nozzle in the side off the burning chamber.
The picture below, show how the fan are placed on 300/400 and 500XXL, the bigger boiler have more
zone below the fire grate.
Primary Fan 2
Primary Fan 1
Secundary Fan 3 and 4
All the fan, have the air intake connected to the boiler bottom part, this have 2 reasons, we cool down the
bottom section on the boiler, and we get preheated air to the combustion, and that is great when we burn
fuel with high water content.