I've got a semi-homemade boiler with over 300' of 3/4" copper surrounding the firebox. It took FOREVER for a little taco pump to get the air out of the system. If you've got much air in your system those little float style traps aren't up to the task. Personally I'd have a boiler drain somewhere to let air out plus use as a source to connect to a high pressure water line to purge the system.