Noisy baseboards...air in system?

[heatmeiser]

I've noticed recently that the baseboards for one of my heating zones are pretty noisy. When the heat kicks on for that zone, I can hear some noise from the circulator pump and then gurgling sounds from the baseboards. My only guess is that there is air in the system and it needs to be bled. I replaced a vacuum relief valve back in early September so perhaps that is the cause of added air into the system? I have a 3-zone FHW system utilizing 3 circulator pumps and Taco switch relays for each pump. I've watched some YouTube videos on how to bleed air from the system, but I'm not sure how to do it since I have relay switches. Also, I have yet to see any bleeder valves on any of my baseboards. Can someone tell me how to approach this?

 

[Smooky]

There is an automatic air vent near the draft regulator in one of your pictures. Are you sure there is no air bleed valve at the radiator?

https://www.google.com/search?q=bas...g7bJAhWEPCYKHaRLDMEQ_AUICSgC&biw=1152&bih=554

Here is a fix for that ticking sound:

 

[Sponsor]

 

[heatmeiser]

There is an automatic air vent near the draft regulator in one of your pictures. Are you sure there is no air bleed valve at the radiator?

https://www.google.com/search?q=bas...g7bJAhWEPCYKHaRLDMEQ_AUICSgC&biw=1152&bih=554

Here is a fix for that ticking sound:

I've checked almost all baseboards in the house....haven't found any valves yet.

 

[Dana]

If the zone is pretty short plumbing-wise it's possible that the noise is simply from being over-pumped. Is this a new symptom, or just something you gradually became annoyed with?

If it's actually getting enough flow to heat the place and the noise is from air, the vent at the boiler should eventually take care of it. The location of the vent at the boiler is less than ideal- you usually want it to be on a fatter section of pipe that's straight for a foot or so on either side of it so that the velocity is slower (fat pipe) and turbulence and re-mixing of air is limited (straight pipe). But it should eventually trap and vent all of the air passing by, if more slowly than with an air-scoop or better location in the plumbing.

You'd normally only have to bleed at the baseboards if there is such a large slug of air that it's vapor-locked, and not getting sufficient flow.