RE:  This bulletin is to notify Shelter OEMs, AIRSYS Authorized service companies, and VzW field personnel with New Build AIRSYS HVAC equipment, that the AIRSYS Lead/Lag controller setting for the input Generator Run (GR) signal should be set to NC (Normally Closed).  Bulletin describes the issue and resolution.

NOTENo adjustment is needed on New VFP shelters unless the GR signal was connected after site delivery to the ASLLC.2 controller configured as NC (opens when generator runs)

 I. Bulletin Distribution: 

  • Shelter manufacturers purchasing AIRSYS HVAC systems
  • VzW HQ-EOS
  • Operations personnel with New Site Builds deployed in 2013 equipped with AIRSYS HVAC systems
  • AIRSYS Authorized Service contractors

 II. ISSUE Details:

New shelters outfitted with AIRSYS HVAC systems have been shipping with the AIRSYS Lead/Lag controller setting for the Generator Run (GR) Input Signal set to NO (Normally Open). 

The VzW Cell Site Shelter Standards (see “Alarm Block Low Voltage Wiring Schematic E501” attached) specifies that the signal supplied by the generator is set to NC (Normally Closed). 

This standard describes the following GR Form C contact behavior as follows:

· Generator OFF – GR Signal is CLOSED

· Generator ON – GR Signal is OPEN (in alarm condition)

This means the setting on the ASLLC.2 controller is the opposite of the behavior of the signal and needs to be changed.

III. RESOLUTION: see PDF file for step by step instructions