Technical
Table 1 : Comparing 0.4 in . w . c . and 1.0 in . w . c . working static pressures for active chilled beams .
56 space temperature variations . Comfort levels are improved over conventional methods and occupant comfort complaints are reduced . Care should be exercised when placing beam discharges parallel to the exterior glazing . During shoulder seasons in colder climates , cold surfaces of glazing with poor U-values could potentially accelerate the discharge air bathing these surfaces , and cause uncomfortable room air movement in the form of drafts .
Consequently , ACBs that discharge perpendicular to the exterior glazing offer a more stable and comfortable thermal environment when coupled with superior glazing that allows such placement . 3
Radiant perimeter panels or baseboard radiation also could be used at the curtain wall in the absence of high performance glazing , or for ACBs that are placed parallel to the exterior glazing . Due to the ease at which ACBs provide ventilation effectiveness to the space , beam placement becomes relatively easy . It is not uncommon to observe air turnover rates within the space of 10 to 20 times per hour . The room air mixing within the ACBs provides a more homogeneous temperature distribution , and a ventilation effectiveness of unity is common .
RACA Journal I April 2022
Manufacturers typically publish guidelines for beam locations as they relate to minimum separation distances , minimum clearances from walls and other full height obstructions . Shading of the exterior of the building also helps minimize the radiant effect from the floor and curtain wall , and contribute to higher occupant comfort within the space . 4
INSTALLATION Hanging a beam from the structure is as easy as mounting a light fixture . However , due to their typical operating weight of approximately 15 lb / ft ( 6.8 kg / m ) for 2 ft ( 600 mm ) wide , double deflection units , ACBs cannot be supported by a T-bar ceiling as is possible with fluorescent fixture .
ACBs provide four adjustable hanging brackets that can be fastened to the concrete underfloor via threaded rod or aircraft cable . Seismic locations may require additional bracing . To reduce on-site brazing work , quick-connect flexible hoses and duct connections can be considered , decreasing the overall labor component associated with each unit , and providing a level of flexibility in unit positioning . The piping system should always be
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