Despite a boiler in place, changing a boiler has equivalent costs to a different installation generally. New boilers ordinarily require a new drain, exhaust, or update for the gas line. It is not unheard of to have a new fuel line set up simultaneously due to clogs or buildup. https://www.theegreetingsportal.com/why-you-need-to-have-a-normal-boiler-service-verify-completed/