when i replace a boiler, i really never even see if the baseboard has air vents or not. if you pipe the boiler correctly, position the pump so it is “pumping away” from the expansion tank and boiler, and also buy yourself a spirovent, you should never manually bleed a baseboard again. ( p.s. the spirovent is a micro-bubble resorber which replaces the hardly effective air scoop) e-mail me for more info jack