Start with the existing system
Identify whether the home uses hot-water or steam heat, the fuel source, chimney or venting arrangement, number of zones and the type of radiation. Replacement planning should begin with the system that actually exists.
Do not size from the old nameplate alone
Older boilers are often oversized. Replacement sizing should be based on the building heating requirement and the applicable distribution-system considerations rather than automatically duplicating the old input rating.
Compare more than AFUE
- Equipment efficiency and firing characteristics
- Venting or chimney requirements
- Controls and zoning
- Domestic hot-water strategy, if applicable
- Piping and near-boiler scope
- Electrical and fuel work
- Warranty, startup and commissioning
Condensing equipment needs the right application
High-efficiency condensing boilers can reduce fuel use, but actual performance depends on system water temperatures, load, controls and installation. Higher rated efficiency does not guarantee the same savings in every house.