Corridor Guestroom Supply Systems
Both Hilton and Marriott now require ducted ventilation air to guestrooms. This means that outside air openings at each guestroom via PTAC or VTAC is no longer acceptable. Likewise, operable windows are not acceptable. In response to this requirement, designers are now providing central HVAC units to supply corridor ventilation that also includes ductwork along the corridor with branch ducts to each guestroom.
The photo below shows the ductwork on each side of the corridor with sprinkler pipes and electrical routed in the center above the drop ceiling.
This is a typical condition along most of the corridor. However, the conditions become much more crowded where the main supply duct first enters the corridor as seen in this photo:
Here the duct must exit the vertical shaft and cross the corridor as it splits into the two branches extending the length of the corridor.
You might ask why two ducts and not just one, and the answer is that the small duct into each guestroom would have to cross over (through) the sprinkler piping in the center. Here is a photo of the duct into a typical guestroom:
In most states there is no requirement for a fire / smoke damper. However, California is one state where a fire/smoke damper is required at the duct penetration to each guestroom. Here is a photo of a typical fire/smoke damper:
Terminating the ventilation air inside the guestroom can be done in three different ways. One approach is to run the duct to a diffuser on the other side. The second is to connect the duct to the return side of the guestroom fan coil unit. The third method is to terminate the duct inside the return air plenum of the ceiling space where the guestroom fan coil unit is located.
The advantage of this approach is that the return grille for the plenum can also function as the access panel for the fire/smoke damper. This is the configuration shown in this photo as taken through the ceiling opening for the return grille. The fire/smoke damper is seen as accessible from this opening.
It should be noted that the return air plenum concept can only be used in a non-combustible building construction. Also, any wiring routed through this plenum must comply with plenum rating requirements. Therefore, no smurf tube in the plenum.