Wye strainer keeps getting blocked on boiler

[PineGuy]

I have an 18 month old boiler that was installed with a forced hot water heat loop and a HW storage tank. About 4 times a year I need to clean the strainer. It becomes so blocked that the HW loop starts banging and the water temp at the taps goes way up so you can’t hold your hand in it. I remove a big plug of what looks like sand and mud. Is this normal? Is it just leftovers from the pipe fitting, etc. The last time I pulled it out there was a D cell battery sized lump in there.

 

[ShaunCorbs]

System needs flushing out and needs to be looked at as it’s corrosion / sludge old cast iron radiators / baseboards ?

 

[PETE 123]

Fit a magnetic filter on return to boiler.