Projects involved survey for replacement of boilers, chillers, and air-handlers. Boilers were upgraded to high efficiency boilers. Air-handlers with hot and cold decks were modified from the constant volume 100% outside air to variable volume 33% outside air system with economizer. Temporary air-handler was provided to supply the service area when the air-handler will be removed for repair and modification. The air balance of the hospital was performed and cooling load and heating load were calculated for replacement chiller and boilers.
Provident Hospital was provided with seven 100% outside air constant volume air handlers with cold and hot decks to constant volume mixing boxes for each zone; of which chilled water tonnage and humidifier are undersized. Three air-handlers are also constant volume with constant volume reheat boxes. This ventilation design is for the conversion of constant volume to variable volume boxes and air-handlers. The 100% outside air units are to be converted to return air/outside air/ exhaust air units with economizers with CO2 demand control ventilation of DDC systems. All the supply and exhaust/return fans are provided with VFD’s. The goals of this Ventilation Study are to accomplish following:
· Establish Outdoor Required in compliance with ASHRAE 62.1 and the International Mechanical Code.
· Establish recommended Variable Air Volume Unit settings for minimum air flow.
· Establish fixed air flow offset if required for tracking supply and return air flow and maintain a slight positive pressure. The preference method of pressurization is by space differential pressure control of the return/exhaust fan at +0.02” of W.C.
Challenges included designing cross connect temporary systems to maintain the HVAC requirements during construction and revising the 100% make-up air design with a recirculation design.