Takagi descaling

[Sovplum]

I need help trying to figure out a loud bang coming from Takagi tankless when hot water tap is turned on

 

[Sovplum]

I tried descaling with vinegar cycling well until it stopped completely as if something was clogged. Can someone help me figure this out please?

 

[Sponsor]

 

[Breplum]

Internal clogs on older Takagi are not worth the effort. I've been to Takagi field tear-down class and many issues are not worth the time on older models.
If your sections are easy-clip, then you need to go section by section.