Can anyone recommend the proper check for this recirc line?

Timco

It rattles loud enough to hear it across the house when it’s quiet. It’s been in for a couple months and has gotten worse. I’ve turned the pump down but now it’s doing it again.

hot_rod

A soft seat, conical shape, low spring pop is what you want.
Low lead, of course.
NA51249 in 1/2 sweat

Timco

Thanks!! Will order today / tomorrow.