Heating Help

Check valves on top

Any ideas as to why someone would pipe to check valves into the top of a steam boiler like this?  When I asked a guy at this site he replied that it was a vacuum breaker.  Doesn't seem right or necessary to me.  Any thoughts?  The ball valve stays open throughout operation and they said steam doesn't come out.  I was actually there to check something else but noticed this.  When I asked why it was there they replied because they boiler works so we don't touch it.    Thanks, Mike.

It's a vacuum breaker

if that system has zone valves and a boiler-feed pump, the vac breaker is needed so the boiler won't go into vacuum when it shuts off and suck water out of the tank. This would flood the boiler. 

thanks

Thanks for the info.  I've asked around and the best I can get is that we are only there to maintain that single boiler.  Our company installed it in 2000.  We don't actually take care of anything in the building so nobody seems to know what the whole system looks like.  The only clue I did find in the boiler room was a Trane Tracer panel.  Unless the building is loaded with AHUs that might point to zone valves. 
Next question would be wouldn't it have been better to put a vacuum breaker on instead of a double check valve set up?