The Boiler Smith boiler at the IIAH is an ASME approved boiler and is annually hydrotested to ~200 PSI.  DO NOT touch anything in the boiler house or on an engine or whistle without permission from the IIAH boiler house manager.
 

Atop the boiler house you will see two pipes with attached whistles.  The pipes are connected to the boiler.  These whistles can be blown by event attendees ONLY with assistance from the boiler house manager.  The manager will show you how to open/close the whistle values.