In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Clanging of pipes in hot water return (hydronic) system
Eddie, Thanks a lot for your response. I have zone valves--3 Honeywell F7 9834 (and actually a 4th for a pipe connecting with the hot water heater). I believe the zones are on the supply piping, but I am really not sure. Maybe this helps: there is a pretty wide diameter steel pipe that runs from the top of my furnace to my expansion (Extrol Model 30) tank and through to a junction of that steel pipe and the three copper pipe lines that go to each floor. I have a Watts regulator Series 1156F and a backflow preventer. I have a single Taco cartridge circulator and have two Taco Hy-Vents--one on top of the furnace, and the other on top of the expansion tank (with that same wide diameter steel pipe in between the Taco and the Extrol). The furnace is pressurized between 12 and 15 PSI. Last maintenance a few months ago said no problems with boiler, draft was -06 -01 smoke 0 stack 550 CO2 12% eff 81.25%. A couple days ago same guys that did my maintenance came in to check the clanging, found by boiler pressure around 30 psi, diagnosed a bad Extrol and replaced the Extrol. The clanging (pipe rattling) has gotten worse and they are not returning my phone call. Needless to say, I have no further trust in them, and I am actively looking to replace them.
I hope this is enough information for you to help. Let me know if you need more info. Thanks again.