There are a few reasons why a new boiler will last longer than an old one:

Newer technologies: Newer boilers are made with newer technologies that are more durable and efficient. For example, condensing boilers are more efficient than older boilers because they capture heat that would otherwise be lost up the flue.

Better materials: Newer boilers are made with better materials that are less likely to corrode or wear out. For example, older boilers were often made with cast iron, which can rust and crack over time. Newer boilers are often made with stainless steel or copper, which are more durable materials.

Better manufacturing: Newer boilers are manufactured using better manufacturing processes that reduce the risk of defects. For example, older boilers were often made by hand, which could lead to errors. Newer boilers are often made by machines, which reduces the risk of errors.

Regular maintenance: If you have your boiler serviced regularly, it will last longer. A regular service will identify and fix any problems before they become major repairs.

If you have an old boiler, it is important to have it serviced regularly. This will help to extend the life of your boiler and prevent unexpected breakdowns. Replacing your boiler can be a big investment, but it can save you money in the long run by reducing your energy bills and preventing unexpected breakdowns.