Carrier 39MN21WL4848311XXE Air Handling Unit

Carrier 39M Aero series indoor central station air handling unit, model 39MN21WL4848311XXE, serial 2818U36622, factory marked for service as OSA-1 (outside air unit). The 39M is a semi-custom, double-wall panel air handler built for ducted commercial and cleanroom-type HVAC service; unit size 21 corresponds to approximately 21 sq ft of coil face area and a nominal airflow of about 10,500 CFM at 500 fpm face velocity. Per the unit nameplate (photo 5), the air handler is built up in five sections, left to right: mixing box, flat filter section with (6) 20 x 25 pre-filters and (6) 20 x 25 main filters, chilled water and hot water coil section with plenum, blow-thru supply fan section, and a discharge plenum. Both the chilled water coil (28MCV038DAA065BLNC) and the hot water coil (28MHV238FAA065BLNC) are rated 300 psig maximum operating pressure at 200 F. The blow-thru supply fan section carries two 7.5 HP, 1800 rpm motors rated 460/3/60, 9.7 FLA each (MCA 12.1, MOCP 20 each), with a maximum continuous unit draw of 23.0 amps. The unit is skin-mounted with an Eaton 30 A, 600 V heavy-duty fused safety disconnect and an ABB HVAC variable frequency drive with keypad for supply fan control, plus a factory control/junction enclosure (photos 1, 2 and 4). The ABB drive display was lit and showing operating values at the time of the visit. Chilled water supply and return piping, condensate piping and supply/return ductwork are connected in place; the unit is installed on the plant floor and will require disconnection of the electrical, hydronic and duct connections before removal. Overall footprint is approximately 264 in long x 84 in wide x 90 in high with an estimated shipping weight of 4,500 lbs. No condition testing beyond the observed powered drive was performed.