Cavitation noise question

bruce pirger

A friend just called about what he thinks is cavitation noise and rapid banging sounds from his gas boiler/radiator setup.

Couple of backgrounds...
1. He removed several second floor radiators and capped off the branch pipes. (Please don't aske me why he did that, but I have those radiators in my garage now.)
2. His steel expansion tank does not have an Airtrol tank fitting and no available hole on the bottom of the tank for the fitting if he wants to add one. (There is a drain on the bottom side.) He doesn't know what the air level is in the tank.

Based on my past experience with hard learned but invaluable lessons at my house, I think his system is not fully filled and needs to be topped off properly at the right pressure.
Also, I suggested to him he install manual bleeder valves where the capped off pipes are so they can be opened and vented while the system is being refilled or topped off.
He recently replaced his automatic fill valve assembly (B&G) and rebuilt the Series 100 circulator.

What's the typical approach to adding the Airtrol to a tank that doesn't have a bottom hole available ?

He doesn't want to start removing and replacing anything, so the steel tank will have to stay.

My apologies for amature questions.

Alan

Patchogue Phil_2

series or parallel

Need some more details. Since you mention a circulator, this is most likely a hydronic baseboard radiator system, right? Were these capped off branch pipes for radiators in series (a big loop) or parallel off of a big loop?

bruce pirger

The radiators are cast iron type, not baseboard convectors.
As for series or parallel, I'll have to ask him.
My first guess is series.
Each radiator is fed by branches off one big loop and output regulated at each radiator.

With the removed radiators sortof at the top of the system, I was wondering if trapped air in those sections can cause this sort of problem, which led me to suggest installing bleeder valves which would be easy enough for him to do.

Thanks for the reply, by the way.

Alan