We recently had a project in a 120,000 square foot existing building where we were tasked with removing existing steam boilers that served a steam to hot water heat exchanger with hot water boilers and installing new hot water boilers.
On start up the system pressure exceeded the relief valve pressure rating of the boilers which is 60# and we couldn’t keep the new boilers on line. We were told that the old system operated at 65lbs -70lbs. Our Cx team found that the bladder type expansion tanks were overcharged allowing the system to operate at 60lbs -65lbs. We reduced the charge on the expansion tank bladders to the required operating pressure of 40lbs. Not only did the boilers function properly, but serval Air Handling Units and Unit Ventilators that had not functioned properly for several years began to function properly. The system operating pressure was preventing the controls valves from closing. While commissioning our work we solved a long standing Building System problem.
While Commissioning a large rooftop air handling unit at Morgan State University we found that the economizer and de-humidification cycles were note operating properly. We found that the humidity sensor, which controls these cycles, was mounted too close to the exhaust ductwork connection. This was allowing false readings to be sent to the BAS System. The humidity sensor was relocated and the system works as intended. Read the Installation and Operation Manuals.
While Commissioning a Project for M&T Bank, we found a Rooftop Unit that would not maintain Discharge Air Temperatures programed into the BAS System. We found that the unit was started up and set to provide local control, ignoring the BAS System. We flipped a switch in the unit and it now works as intended. Read the Installation and Operation Manuals.