Over the last month, my Taco circulator pump has started to make a rattling sound and I'm hearing "girgling" and "whoosing" sounds when the water runs through the baseboard. Based upon some websites, it looks like I need to bleed the zones. (There are no bleeders on the baseboard; I've checked). I've checked this chatroom and found different answers so I am posting to try to get a consensus.
The circulator is connected to the supply side. Right after, there is a ball valve. This branches into the three zones. Each zone has a ball valve, a shutoff valve w/ bib (you can attach a hose to it) and the zone valve. There is also a ball valve on the return side for each zone and the return line into the boiler. I've tried to attach photos to give you a clear picture of the system.
The pressure in the system is fine and it seems that the system warms up fine (although it does take longer than last year).
You need to install some air bleeders on your baseboards. Without going to the highest point it may be tough. Do you have a expansion tank with a air scoop and vent? That should get most of the air out.
Are there any spots to install air vents or would you have to do some piping on the baseboards.