Clean & Safe Hygienezertifikat

Ductless Mini-Split Systems

30. Dezember 2019


To replace coo­ling towers loca­ted on the 52nd level of a com­mer­cial high-rise buil­ding in down­town Los Angeles.


This cli­ent cho­se Mesa becau­se of the company’s exten­si­ve expe­ri­ence in per­forming com­plex air con­di­tio­ning sys­tem retro­fits on a turn­key basis. From the start, Mesa faced two chal­lenges. First, the building’s coo­ling had to be main­tai­ned while the coo­ling towers were being repla­ced. And second, the units were loca­ted at the top of one of the city’s tal­lest buil­dings, neces­si­ta­ting the use of a heli­c­op­ter to lift the new units abo­ve Los Ange­les’ busy streets.

To address the first chall­enge, Mesa demo­lished and remo­ved half of the exis­ting cells, lea­ving the remai­ning cells to con­ti­nue coo­ling the buil­ding. After moun­ting seis­mic iso­la­ti­on bases and springs, Mesa instal­led two indu­ced-draft coun­ter­flow coo­ling towers. The units were orde­red in mul­ti­ple sec­tions weig­hing less than 3,500 pounds, so they could be lifted by heli­c­op­ter. Mesa made all arran­ge­ments for the heli­c­op­ter ope­ra­ti­on, inclu­ding obtai­ning street clo­sure per­mits, secu­ri­ty per­son­nel, and con­trac­ting for truck­ing sup­port ser­vices. To mini­mi­ze dis­rup­ti­on to buil­ding ope­ra­ti­ons and ensu­re maxi­mum safe­ty, the com­pa­ny dis­mant­led the old equip­ment and remo­ved it uti­li­zing the buil­dings freight ele­va­tors after hours. Mesa orchestra­ted the two heli­c­op­ter lifts on Satur­days when buil­ding occu­p­an­cy and street traf­fic were reduced.

Each tower included three cells, each fan dri­ven by a 40-hor­se­power, 460-volt varia­ble fre­quen­cy dri­ve. Mesa pro­vi­ded tem­pe­ra­tu­re con­trols through an inter­face to the building’s DDC sys­tem, enab­ling moni­to­ring of the sys­tem ope­ra­ti­on and ener­gy con­sump­ti­on and ope­ra­ting cost reduc­tions. Mesa instal­led new fan dis­con­nect swit­ches, water piping, two tower clea­ning sys­tems, walk­way gra­tings, and stain­less steel exhaust duc­ting from each cell up through the roof. After the tower instal­la­ti­on, Mesa per­for­med start-up and com­mis­sio­ning ser­vices for the first two towers and com­ple­ted the same work for the second half of the coo­ling towers befo­re tur­ning the com­ple­ted pro­ject over to the owner.


City Natio­nal Pla­za encom­pas­ses an enti­re city block in the finan­cial area of Los Ange­les’ cen­tral busi­ness dis­trict. Com­ple­ted in 1972, it con­sists of two 51-sto­ry office towers, one pla­za level buil­ding, and four sub­ter­ra­ne­an levels, com­pri­sing in total more than 2.6 mil­li­on squa­re feet of ren­ta­ble space.



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