F22B13/00—Steam boilers of fire-box type, i.e. boilers where both combustion chambers and subsequent flues or fire tubes are arranged within the boiler body
F22B13/02—Steam boilers of fire-box type, i.e. boilers where both combustion chambers and subsequent flues or fire tubes are arranged within the boiler body mounted in fixed position with the boiler body disposed upright
F22B13/023—Steam boilers of fire-box type, i.e. boilers where both combustion chambers and subsequent flues or fire tubes are arranged within the boiler body mounted in fixed position with the boiler body disposed upright with auxiliary water tubes inside the fire-box, e.g. vertical tubes