HVAC Question: Ventilation for Natural Gas Boiler (1 Viewer)

[captain_amazing]

I know little about HVAC and am looking for help.  I have a natural gas system, oddly on the second floor of my house.  The system vents everything through the roof.  In the room, there are three vents that are open to the outside on the wall nearest the heating system: one near the floor and two near the ceiling.  

My question is, what purpose do those serve and do I need all three to be open?

 

[Galileo]

Other than the three vents, is the room otherwise sealed?  I am not an HVAC guy, but combustion of natural gas requires a mix of air.  The system needs to draw in air from somewhere.  If the room is sealed preventing an adequate supply of air from inside the home, the vents may be necessary to draw in outdoor air.  You need about 10 cu. ft. of air for every 1 cu ft. of natural gas burned.

 

[wilked]

Picture would help immensely