Boiler Safety is a constant concern:
Who and when was the last time someone drained the mud from the water level control?
Have we tested the auto water fill control lately?
Did the burner service test the low water level and fill system?
These boiler safety controls need periodic maintenance and cleaning. Proper inspection and testing cannot be over emphasized.
Is there a water meter on the fresh water fill supply line? This will tell you when there is a leaking return line.
What is the Ph value of the water in the boiler? Chemicals may be needed to preserve your boiler.