we are building a computer datacenter. room is 18' x 16', concrete walls and 2/3 below ground level. average temperature is about 65-70 degrees F with fairly low humidity (Northern California).
initially we will have two 42U server racks that pull a total of 13000 Watts under full load. electrical power feed is three phase to an in room distribution box and dual 208V/30A twistlock feeds to the racks.
we plan to expand the datacenter 200-300% in the next 2-3 years (maybe 30-40,000 watts). how much cooling should i be looking at given the growth i am expecting? i have researched this topic and folks caution not to over-estimate your need otherwise your cooling unit will short cycle and such. of course underestimating could also be a serious issue.
based upon my limited knowledge, i am thinking a 4 ton Mitsubishi split ductless unit would be a good fit. can anybody offer me a little advice?