period four
Equipment Sound Rating
notes
Air Handler Test Configurations
ducted | ducted | |
discharge | ||
inlet | ||
|
casing | unducted inlet | |
plus casing | ||
radiated | ||
radiated | ||
|
Figure 64
In order to isolate these different paths, the air handler must be tested using a number of different configurations. For example, to determine the portion of the sound that is discharged with the air into the supply ductwork, the air handler is installed outside of the reverberant room with the supply air ducted into the room.
In order to determine the sound that travels back down the return duct in a ducted inlet application, the air handler is again installed outside of the reverberant room, but the return air duct is connected to the reverberant room.
In order to determine the portion of the sound that is radiated by the casing, the air handler is installed inside the reverberant room with both the return and supply air ducted outside of the room.
Finally, in cases where the return air travels back to the air handler through an open plenum and into the open equipment room, the combined “free” (or open) inlet plus casing radiated sound level must be known. Therefore, the air handler is installed inside the reverberant room with a free inlet and the supply air is ducted to outside of the room.
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