I got my Burnham Freedom 120 installed a few months back, and everything about it is great, except for the noise from the exhaust. My heating bills have been cut in HALF, I have reliable hot water, and I've regained about 10% of my basement thanks to the removal of my old oil furnace.
However, the noise from the Burnham is getting annoying. Its piped up from the basement with their special concentric venting kit, and goes out the side of the house near the corner of my living room. When the boiler fires, it starts out very quiet. After about 5 minutes of firing, the exhaust starts to burble and bubble. It gets progressively louder for about 3 minutes, then abruptly quiets down. No more bubbling, no more burbles... just the expected exhaust noise. After another 5 minutes, it starts again. Repeat until the boiler is shut down by one of the zone valves. The contractor, who I've been extremely pleased with, says he's never heard one like this, and has contacted Burnham, but they don't have any ideas.
So... is it possible that condensate is pooling somewhere in the piping (which is only about 6' long), or is this just something I'm going to have to live with?