As part of this project, we have replaced two large rooftop units that provide air conditioning and heating to the 5 floors of the office building. The existing 75 and 105 tons units were installed by us in 1990 in the original construction of the building. The challenge was to make the replacement of both units in the shortest time possible with the least possible discomfort for the building occupants as all office space was fully occupied. Strict planning permitted the work to be carried out in one weekend starting Friday and performing the unit start-up on the Sunday. This work was also carried out in parallel with the roofing contractor and the electrician who worked for directly for the building owner. Both air handling units were successfully replaced within the allowed timeframe.