ALAN IL SCHWARTZ PE CONSULTING ENGINEERS 353 W. 481" STREET NEW YORK, NY 10096 Richard Kahn HBRK Associates Inc. 575 Lexington Avenue, 4th Floor, New York, New York 10022 July 26, 2013 Dear Mr. Kahn, Re: 9 East 71st Street New York, NY Engineering Report The following is based on our investigation of the conditions in the 3" floor bedroom in the above space. The purpose of the investigation is to attempt to remedy any adverse comfort conditions the space. The investigation consisted of a review of the existing design drawings for the building, the modification of the bedroom system previously completed, and an inspection of the cellar and 6" floor mechanical rooms as well as a non-destructive inspection of the bedroom and surrounding area. 1) Based on the existing drawings the return air in the sitting room and bedroom totals 1670 cfm. The air originally supplied to those two rooms totaled 2735 cfm. With the addition of the 10 ton air handler, the supply air into the bedroom had increased by an additional 1000 cfm, resulting in a total difference of over 2000 cfm. The original return was designed as a "plenum return;" the return duct collects air above the ceiling, requiring the air to migrate to the space above the ceiling thru architectural slots above the bedroom crown molding. We recommend: a) increasing the quantity of return air to the space by installing a booster fan in the return ductwork to match the increased air flow generated by the supply air handler. The booster fan should be installed as far away from the bedroom as possible (potentially near the service stair) to minimize any sound generated from the fan. b) Reroute the ductwork in the corridor to allow the return air to be collected below the ceiling, but above the crown molding. c) The above recommendations for duct modification are based on review of the existing DESIGN drawings and visual inspection of all conditions below the ceiling. The as built conditi