bearing vs non-bearing wall

does anybody know whether the wall separating heater&boiler room and stairways (2nd floor) is a bearing wall or not?

and whether or not the support beam (that seems to go "inside" that particular wall mentioned above) actually goes all the way to brick wall?

i'm planning to open that space so the 2nd floor looks roomier. So far, I have two conflicting answers and hopefully this forum can settle it.

thanks!
-Will