Editor’s note: Hollywood long has been known for—ahem—taking liberties with the truth (just ask any composite character). In HPAC Engineering’s ongoing series “HVAC in Popular Movies: Did Hollywood Get It Right?," Ron Wilkinson, a professional engineer who moonlights as a film critic, takes a look at movies and television series whose makers may or may not have let HVAC fundamentals get in the way of a good story.

The Boondock Saints (1999)

In this cult crime film, Sean Patrick Flanery and Norman Reedus play Connor and Murphy MacManus, Irish American brothers who believe they are on a mission from God to rid their home city of Boston of evil by killing off mobsters one by one or, in one scene, nine at a time.

After learning of a meeting of Russian crime bosses at a hotel, the vigilantes stock up on weaponry from a local underground arms dealer. Connor (Flanery), to Murphy’s dismay, insists they need rope because Charles Bronson always has “a lot of rope strapped around him in the movies, and they always end up using it.”

The brothers plan to sneak up on the crime bosses through the hotel’s ductwork. As usual, there is no perceptible airflow through the duct (it messes up the hair). Also as in most films (see “Mission: Impossible,” “Jurassic Park,” “Die Hard,” and “Die Hard 2”), the ductwork easily holds the weight of two men, but, in a rare case of HVAC realism, finally gives way, leading to a spectacular fall through the ceiling in a shower of Sheetrock, sheet metal, and debris.

After Connor and Murphy dispatch the bad guys and leave the scene, the FBI, led by Agent Paul Smecker (Willem Dafoe), shows up to investigate. As Smecker deduces: “Television. Television is the explanation for this. You see this in bad television! Little assault guys creeping through the vents, coming in through the ceiling. That James Bond (expletive) never happens in real life! Professionals don’t do that!” It is a rare example of Hollywood satirizing itself for the oft-used trope of the ductwork escape. The film makes up for this rare self-criticism by opening with one of the MacManus brothers tearing the water closet from its plumbing and anchors and dropping it six floors on the …. Never mind; you will have to see the movie to believe it!