pipe noise

Dan M

My two pipe hot water heat system has a steady "Hum" or harmoic sound that can be heard in the 1st floor of my house when nothing else is running. Last year during a remodel I replaced the old steal pipes with new copper (1")and set them back in the walls ( well insulated). I followed the old piping route where it made sense and tried to simplfy were it didnt( got rid of some weird add on's)The system is set for continuous circulation with a single punp (Taco 007). The system had a 011 large pump that I removed because of noise (Before pipe replacement). The 007 was a big improvement and the noise level is very low, less than that of any forced air system etc. The system heats well with good circulation .My main question is is their anything I can do further, or is this just a product of my amature piping( too many elbos or tees or what ever)?

Thanks
Dan

Mike T., Swampeast MO

Harmonics/Resonance

(at least that's what it "sounds" like you're getting)

Small, but regular vibrations (say from a circulator) can sometimes resonate through the pipes. The first thing you should do is make certain that all of the piping is well-supported and secure. Such can go a long way towards reducing/eliminating the noise.

Mark J Strawcutter

are you pumping away?

I've encountered a situation where the circ was on the boiler return and changing radiator valves increased the pressure drop enough that cavitation started which in turn resonated thru the pipes - primarily the returns. You could actually feel it by touching the pipes. The old cast iron radiators seemed to have enough mass that they dampened out the vibration so it wasn't present on the supply lines.

If your circ is on the boiler return, perhaps the downsizing of piping is causing cavitation.

Mark