Please help me with the age of this low pressure steam boiler
Big Blue Burnham boiler.
Yep, you’ve got a grand-pa on your hands.
The serial number should be 8 numbers long. Some of the older boilers only had 7 digits (like the one you have there) and those are not traceable because it was before Burnham began tracking numbers via computer.
For manufacture dates, speak with Customer Service”