I have a 1 1/4" weighted Taco check valve, that clatters. It is installed between the supply and return manifolds. There is an elbow about 4 inches before it. I have my system plumbed to Tarms specs with a Termovar valve on the return line to keep the return temps lower and allowing the storage tank to charge. Is is just a bad check valve, or is the elbow creating turbulence? Any ideas?