Well, the problem isn't 75 years old but the boiler is. I have a
Weil-McLain oil boiler converted to gas....size 5-w-19 series D...

Efficiency expert said the boiler was handling the house fine so didn't
consider replacing it. One of the pipes started leaking and the Gas company
replaced the pipe and put in an over flow valve (none was there). The valve
drips all the time.....(a bucket a day). People talk about an expansion
tank (there is NONE). Others suggest that the overflow valve should not
have been installed. The boiler is running fine but sure is a pain to empty
the bucket everyday... Any thoughts, comments or possible solutions
appreciated. John