To ensure boiler continuous operation while avoiding production stoppages in the event of fuel pump failure, a second backup pump is provided, installed in parallel with the service pump.

Through a selector switch on the control panel is possible to select the pump enabled for operation and the one that will remain on standby for possible failures.

In case of failure of the circulation pump, appropriately signaled by an audible and visual alarm on board electrical panel, it takes place the automatic exchange of the pumps and began working the standby pump.

The standby pump control is done in the same way as for the duty pump.

Both pumps, hydraulically connected to the same supply pipe, are accompanied by dedicated non-return and shut-off valves, to prevent the flow of water against the pump standby.