so you're sticking 2000 watts of heater in the ten-inch plenum of a cheaply-built office building in which you clearly (from the pics) do not occupy the top floor?
and the people in the office above you - which is an office, as floor plans are predictable - won't notice this and get freaked about it... why?
never mind the heat required to spontaneously combust any number of things in the plenum that you'll be heating to 85 C - like the various adhesives, and the wood itself after the fire-retardant chemicals it's infused with evaporate.
holy mother of god.
congratulations on winning the first ever time-shifted Darwin Award...