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Pipes humming at same time 4 days a week - DWP or us?
« on: Today at 05:23:35 PM »
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Hi,
For two months now, every week, four mornings a week at exactly 5:37 a.m. our pipes start humming really loud for exactly ten minutes and then stop, just like that. We've had the regulator changed and it still does it. We've unplugged the sprinkler clock and it still does it. Our plumber has had us shut off things one at a time each day that it happens and it still does it.

If you put your hand on the outside pipes (holding the regulator) you can feel the water pressure rise inside and it starts humming. We've had the DWP out to the house twice - of course it's later in the day when this is not happening, and they say nothing is wrong. None of our neighbor's sprinklers go on at this time.

We've shut the water off from the DWP meter at the street while it's happening and it stops. As soon as we open the valve back up, it starts humming again and our T-bar on the valve vibrates. This is the part that comes up from below the street and goes into our meter, not on our side of the meter. We don't think it's the mainline.

Tomorrow morning we're going to put the pressure reader on the faucet hook-up by the regulator and see if the water pressure goes up when this happens. The meter reads 60 right now. When we test it at the front of the house by the sprinkler hookup, the pressure meter there reads 120.

We think that the DWP valve by the street is worn (from 1962 when the house was built) or maybe has a hairline crack and that for whatever reason the water pressure rises for these 40 minutes per week under the street, it can't handle it and that comes up to the house.

Any ideas?

If it happens 4x a week at same time - than it is some kind of timed device. It can be sprinkler, house filtration system, drip system, pool filler, etc. See if there is any timer attached to any water outlet in your house.

Your theory about the "crack in water main" seems to me to be far fetched...

Thanks Milo. We've thought of all of that. The only thing on a timer is our sprinkler system that comes on at 8:45 a.m. We've unplugged the whole system from the wall and it still happens. I know my theory sounds far-fetched, but the DWP meter by the street always has water in it on the street side of the meter. Sometimes the level is higher than others, but wouldn't you think that something might be leaking because of this?

Just a question but do you have a water softener?

Hi, no water softener, but when we bought the house ten years ago, they did have a water softening system. We never used it and had it removed five years ago.

I just had a thought, some people when thinking about their plumbing forget about a softener.

I can't think of any thing else that would be that close to the same time each day and only so many day a week it does it and them some days it don't.

Here is another thought. If you have an electric water heater do you have a time clock on it. Oh another thing is a defrost timer on the fridge and or freezer. And if you have an ice maker it is possible something there is making it do it.

I am out of ideas, hope you find it and when you do please let us know on here, someone else might have the same question someday.Ha ha but I can hear you now saying (let them find their own dan problem) ha ha.

Thanks. I've been on another site and had a back and forth with a master plumber. After exhausting every idea - we've tried them all - he suggested installing an expansion tank to absorb the extra pressure.

We'll try it and see.

Thanks for responding.

How about refiling toilet tank ?

If you put your hand on the outside pipes (holding the regulator) you can feel the water pressure rise inside and it starts humming. The meter reads 60 right now. When we test it at the front of the house by the sprinkler hookup, the pressure meter there reads 120.
Has the plumber replaced the PRV valve,(see image)? That would appear to be faulty. The average house pressure's 45 PSI with 70 PSI the tops. 120 PSI is way high. This can put a strain on joints and faucets. Have it looked after.
Adding a expansion tank may or may not help but it still doesn't get to the source of the problem. Replace the PRV valve, get your house pressure down where it belongs and go from there. Good luck, Tom

Thanks. The first thing the plumber did was replace the PRV valve. It's set at 60, though we might set it lower, but the water pressure in the house is fine.

Except for those 40 minutes in the early morning every week, everything is fine in the house.

What else do you have out there? Anything you haven't mentioned?
You tell me,
When we test it at the front of the house by the sprinkler hookup, the pressure meter there reads 120. Is this before or after the PRV valve? Regards, Tom

Hi Tom,

This is before the PRV valve. I've been on some other forums and it was suggested that we install and expansion tank and if that doesn't work, a hammer arrestor, so we're going to try that. I've been on the phone throughout this with the DWP and they're basically saying it's our problem even though the vibration and surge starts from the street side of the meter.

A expansion tank acts as a hammer arrester . This may help but you still haven't located the source and that bothers me. I keep coming back to the fact that your sprinklers are running at twice the pressure it should be. The sprinkler feed should come after the PRV valve not before it. I can't explain why but in my gut I feel that this has some bearing on your problem. Where is the sprinkler feed in relation to the PRV valve? Tom

The sprinkler feed is at the front of the house where our main cutoff switch and PRV valve used to be. We had some problems about five years ago and the main cutoff and PRV valve were moved to the side of the house, so the sprinkler valves are before the PRV valve.

Other people have told us that their houses are like this and the pressure is higher up front but they like it higher that way.

Hmm...

Do you have a timed hot water recirc pump? What kind of water heater do you have? Some tankless water heaters will have a built in timed recirc. Im just throwing this out there. Very curious to hear what you end up finding. It happens at exactly the same time, only four days a week? Interesting. Please keep us posted, as I do believe I'm about to learn something here.

Have you talked to your nabors, have they Had any trouble like this I bet it is something the city is doing, effecting the whole street.

Joshdta asks you good question. If this is City Water Delivery related problem the chances are that some of your neighbors are experiencing the same problem. Please, find out and let us know... Thanks... Milo

Just thought I'd give an update. I spoke to someone at the DWP on Tuesday in the Field Investigative Office who actually seemed like she cared and said she would ask around. We had previously asked for someone to come out that morning at 5:37 to check the meter and were under the impression that they would come. They came at noon when I was out and left a note saying there was "No problem here. Water pressure is fine."

Well, of course it was fine at that time of day. Anyway, the pipes haven't hummed since Tuesday after I spoke to the woman at DWP and the guy came out to check our meter. I'll never know what he really did, if he fixed something or changed something.

Got a call back from the DWP lady on Thursday saying she'd asked around and no one could think of an answer. Gave us the number to the Department of Building and Safety because they regulate the water pressure in neighborhoods around the city.

Because the pipes haven't hummed since Tuesday (it's Saturday now) we're waiting to call DBS the next time it happens. My thinking is that someone knows what's going on at the DWP and because I finally complained to the right person, they fixed it. At least that's what I'm hoping. We'll see if it happens again, but right now it's so nice to sleep in past 5:37 in the morning!

Thanks for the update and please keep us informed of farther developments . Regards, Tom