We have a Weil-McLain Gold Oil Model # P-WTGO-4, Series 3 hot water/heating system. We ran out of oil & now need to restart. We're pretty clear on how to bleed the air out of the oil lines, but are a little confused concerning bleeding the air out of the water line. The manual we looked at mentions multiple air vents that need to be bled individually for each floor. My question is, where are these multiple vents? Are they on the heaters in each room? Or are they located on the pipes or the heater itself in the basement? Any information will be more than we know now! Thanks.