I had a new Burnham Independence boiler installed by a reputable installer almost two years ago. It worked very well through the first winter, no noises, heated well. No issues.
Before this winter we had it serviced and ever since it's been a little noisy. The sound of boiling/gurgling water in the radiators, more vent whistle noises, some hammers, and even this sound. It sounds like a drum roll going on inside the boiler, mostly heard at the exhaust vent piping, that lasts for one second. And it repeats about every 30seconds as it gets cranking.
I checked the pressuretrol and it was set to 2psi with a 1psi diff. Today i lowered the main to about 1.7, as low as the slider would go with the same 1psi diff. The boiler has kicked on since with only very minor clunks/hammers, but the drumroll noises aren't perfectly repeatable. So we'll see if that does anything. I suspect my system never gets to that pressure anyway, i've never seen the needle on the gauge budge, granted its a wide range gauge.
Here's a link to a video of it: https://www.dropbox.com/s/c8vqdna4wvgrdeh/BoilerNoise.m4v?dl=0
(its at 14s and 34s)