OT: Noisy Water pipes?

joe_130

hey mitch that sounds like a real pain. It sounds more like a problem from elevated pressure than from flow. Pressure reducing valves are installed downstream from the water meter, not more than a few feet away. You mentioned that you get your water from the city and if it is more than 80 psi (i've sdeen it be as high as 120 psi) you need one. You should buy a pressure gauge (from 0 to at least 200) and screw it on to your sill cock, and turn it on, they cost about 15 dollars. if its more than 80psi you know you have a problem and should call a local plumber.

good luck

joe

Mitch Patrie

OT: Noisy Water Pipes??

Greetings -

My house has extremely noisy pipes at elevated flow rates. The problem is most apparent when the in-ground sprinkler system is operating, but I can reproduce it if I just turn on a bunch of faucets inside the house: in other words, it seems to be entirely dependent on flow rate. Noise gets excessive when flow rate is higher than about 1/2 CFM (sprinklers use between 3/4 and 2 CFM). The copper pipes are 1 inch ID, which translates to a flow velocity of up to six feet per second. Several sources recommend keeping flow velocities below eight FPS to reduce noise and pipe erosion, so I think we're OK there.

Here's the weird part. The noise isn't just a typical hiss or rush of water through the pipes. In fact, that's a pretty minor part of it. Instead, there's a ticking/growling sound that constitutes virtually all of the noise, operating somewhere between five and fifteen cycles per second; the exact frequency is proportional to flow rate, and it's an extremely even rhythm (i.e. it's not like the ticking of thermal expansion). Last night I watched the meter and observed 25 ticks/pulses per tenth of a cubic foot, i.e. 250 pulses per cubic foot. My suspicion is that the water meter is the source of the noise, and that the piping system is somehow amplifying it.

I talked to the city water department last Thursday, and found out my meter is rated for over 3 CFM, so it should not have been a problem. Still, the water dude came by my house on Friday morning and swapped it out for a larger meter good for 4.5 CFM. The noise changed a little bit (lower frequency), but it's still there and still loud. The city water dude was as baffled as I am. Both of these meters were AMCO C700; the first one was a 5/8" throat, the second a 3/4" throat. The meter uses an "oscillating piston" mechanism to measure water flow.

While he was still there, I turned off the sprinkler system and went through the house and turned on all the faucets. The noise was the same, which means it's not the sprinkler system causing the problem.

We don't get any noticeable noise when drawing water at lower rates, such as a shower (2.5 gallons per minute = 0.33 CFM). It's really only a problem when we're running the sprinkler system; it's hard to enjoy a nice quiet evening at home when the whole house is growling.

I was told by some folks that I should look for a pressure regulator. We are on Ann Arbor's municipal water supply. The supply comes up through my concrete basement floor, and after a ball valve, the meter is the first thing it hits. There's no pressure regulator downstream of this point; if there's one upstream, then it's out by the street and I haven't seen it. If this is strictly a concern about flow rates, I'll reiterate that the peak flow velocities are within recommended values for copper pipes, and the peak volumetric flow rates are well within the ratings for the water meter.

Is it possible I have two bad water meters in a row?

I'm not sure what to do next. My only idea at this point is to buy several "water hammer" supressors and install them at various points in the piping system to see if I can damp out the sound.

Anyone have any other ideas?