Hi all - Well, I think I have solved the problem I've been having in the noisey baseboard. The zone that fed my bedroom has those "Sharkbite" connections in them. I did that a few years ago when I had to service the zone and I had completely forgotten about them. Due to construction, I had to extend the zone in my bedroom into another room where heat did not exist and that's when I found the Sharkbite connectors. I took them out and sweated in everything I needed to extend the zone. After purging the zone of air, I let the OWB do it's thing and at the moment all is quiet when the room asks for heat. I'm hopeful I have stumbled upon the problem. I'll keep you posted if the problem shows up again. Roger