We live in a 1920 Sears and Roebuck kit house with a one-pipe steam heat system. We have a Weil-McLain boiler that was installed at least 20 years ago. According to its specifications its input is rated 240.000 BTU/hr and output of 192.000 BTU/hr. The system is noisy and our gas bill is very high every winter (up to $400), but it has not failed us yet. On a side note, in the 1980s a separate A/C system was installed - one unit in the cellar and a second one in the addict.
My two questions are: (1) When should I replace my heating system and (2) what should I replace it with?