Text: In some cases, however, the preferred approach has been to locate the SCR reactor on the ground near the boiler and to route the ductwork to and from the SCR reactor.
Entailment: However, in some cases, the preferred approach has been to locate the SCR reactor on the ground near the broiler, and then route the ductwork from and to the SCR reactor.
Contradiction: In all cases, the preferred approach has been to locate the SCR reactor in the air far away from the boiler.