SylvanLMP
This sounds like a STEAM system where either the new lines are back pitched ( steam hitting condensate) OR the main vent is improperly installed dont forget the 27″ for the MAIN vent.
Plus all your other vents to make sure the condensate doesnt become air bound.
I would strongly suggest you re read the manufacturers NEAR BOILER PIPING DIAGRAM.
Unfortuntly a lot of NON licensed folks Especially “journeymen plumbers” think they know “heating” and pipe systems wrong.
Steam is not as forgiving as hot water when it comes to boiler sizing or piping arrangements.
Check the header for pitch and make absolutely sure the installer did install a Harford loop as you certainly dont want a melt down.
No matter what someone says about the safety and operating controllers YOU still need this added NON MECHANICAL protection.
Have a great week end.
