Cast iron boilers, on the other hand, should be considered for replacement if they have been operating for more than 20 or 30 years. Some of these boilers can last up to 50 years or more, but even with decent annual maintenance, their efficiency is much lower than that of current cast iron boilers. It may be something you can fix yourself, but it could mean that your boiler needs maintenance, repair, or replacement. This saves the time and cost of reinstalling and wiring the boiler, and could save the cost of applying for permits if the work is considered a repair.
When a manufacturer stops making a certain boiler model, they may continue to manufacture replacement parts for a few years, but will eventually stop when the number of boilers is too low to be worth it. When considering repairing or replacing a boiler, first assess the condition of the metal from which the boiler is made, by any available means. As mentioned, the condition of the metal from which the boiler is made is a primary consideration for boiler repair or replacement. If a low-pressure steel boiler has had parts other than tubes repaired, such as the housing or sheets of tubes, it is reasonable to assume that the boiler is near the end of its useful life.
Obviously, discarded pipes or cast-iron sections in the boiler room are evidence of boiler repairs.