An installer is asked to add a monobloc-style air-to-water heat pump to an existing hydronic system that is supplied by a mod/con boiler.

A technician encounters a system installed in the 1980s when radiant floor heating was relatively new in North America.

A homeowner hires a heating contractor to upgrade his propane-fired cast-iron boiler to a mod/con boiler. The cast-iron boiler is only 15 years old and in good shape.