if you look at the picture and you should see what is their ive worked on this type of boiler and others for 18yrs and yes their is a tpr and what are you worried about having it done manualy thats how its done, every thing works together the gray box is for adjusting the temp as well inside the temp when it shuts off, the bladder is in the attic, ive heard of this before my preferance is next to the boiler and you only need 12 pds of pressure on the reading and the pump must work you can have it run all the time or cyle on and off looks old? but it should work as long as its not leaking just clean it out inside it should have 5 arms make sure that the are clear and the flue is in good shape i could go on but like he said no water no check and the gauges would tell it all, the air graber should be replaced its bent