He have a new boiler installed with indirect water heater. The house has only one zone and the indirect water heater is another zone. There is this Taco 'swet check 241' valve between the heating return and IWH return. My plumber told me that the valve is there to isolate IWH circulation from heating system.
Everything seems to work well except that when the boiler is working for heating( in which case the return water flows through the valve I think), it has gentle knocking noise from the valve. It sounds like some kind of ball bearing hitting the pipe. It's not that loud but when everything's quite in the bedroom I can hear it from the radiator and it gets me. My plumber told me that's the way it is but I have some doubts. Is it really normal to have that kind of noise or a sign of something wrong?
I tried opening up the valve partially and the noise goes away. But then it won't separate the IWH zone from heating zone right?
Thanks advance for your insights!