"I have a Beckett AFG oil burner and I want to change the oil filter on my furnace. If I close the valve coming into the filer and change the filter... do I need to bleed air out of the system or can I install the new filter and open the valve and fire her up? I have the 2 line system with the return line going back to the tank. Someone said I will need to bleed air? How would I get air in the system if I have the valve closed at all times until the new filter is installed... HELP Thanks"