Sporadic Rumble in Pipes

About a week or so ago I started hearing a rumble in the pipes downstairs. It lasts about 10-15 seconds. I've narrowed the noise down to what used to be the laundry room. There are two narrow pipes coming from the wall that feed hot and cold water to an old sink, but they haven't been used in years. About a month ago, construction up the street led to someone shutting off the water without notifying everyone. When I got home I flushed the toilet and there was a loud noise and water sprayed up from the tank. I shut off the tap and went to talk to my neighbours. Long story short, I turned on all the taps in the house to release the pressure, all but the one in the basement, which I forgot about. Then last week the noise started. When I opened the taps downstairs today, there was a little spitting, but not much. I noticed the flow of hot water was stronger than the cold water.

The noise is not constant. Today it happened once in the morning and again after 9pm. It doesn't appear to be connected to regular water usage.

Any ideas?

Cap

Sounds like air in the pipes. It should all eventually go away. You could accelerate the process by repeatedly
bleeding the air out of all your water outlets.

Quote:

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Originally Posted by kreemoweet

Sounds like air in the pipes. It should all eventually go away. You could accelerate the process by repeatedly
bleeding the air out of all your water outlets.

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How? Do I shut off the main and open all the faucets in the house?

Cap

It is NOT air in the pipes, but we cannot tell you what it is without being there to hear it and see when it happens. Sometimes a faulty toilet fill valve will cause "weird noises" somewhere else in the building.

Quote:

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Originally Posted by hj

It is NOT air in the pipes, but we cannot tell you what it is without being there to hear it and see when it happens. Sometimes a faulty toilet fill valve will cause "weird noises" somewhere else in the building.

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It hasn't happened yet today. It usually happens between 8:30 and 9:30 pm. But not every day. It doesn't happen after someone flushes the toilet or takes a shower or runs the dishwasher. The toilets seem to flush normally, by the way. Nothing has changed prior to and after the noise (cross between a rumble and moan) began. The sound is definitely coming from the corner of the old laundry room where the cold and hot water pipes come out of the wall. What should I be looking for?

I imagine that if I call in a plumber the noise won't reoccur and I'll just be out a couple hundred bucks.

Cap

So, how serious is this? It happens about once a day so chances are it wouldn't happen when the plumber is standing there listening. It seems like air is building up somewhere and then is released, but you say it isn't air in the pipes. Would changing the guts of the two toilets stop this annoyance? Should I be worried about pipes bursting?

Cap

How serious? Well, all we know is that you hear a funny noise for a few seconds maybe once or twice a day. How could
anyone call that serious? I've lived in many old houses, and they are ALWAYS making funny, unidentifiable noises. If its really
bugging you, why don't you open up the wall where you say the noise is coming from and have a look? Hire a neighborhood
kid to sit down there every morning to keep watch? Or, if you've got money to burn, hire a plumber to come in and start
replacing parts at random?

Quote:

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Originally Posted by kreemoweet

How serious? Well, all we know is that you hear a funny noise for a few seconds maybe once or twice a day. How could
anyone call that serious? I've lived in many old houses, and they are ALWAYS making funny, unidentifiable noises. If its really
bugging you, why don't you open up the wall where you say the noise is coming from and have a look? Hire a neighborhood
kid to sit down there every morning to keep watch? Or, if you've got money to burn, hire a plumber to come in and start
replacing parts at random?

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This house was built in '65 and we've lived in it for more than 20 years now. This noise started only about three weeks ago and the only thing that happened prior to that was the water shut off and me flushing the toilet without knowing it had been off. I have a feeling that may have damaged something in both toilets, but I don't know if that is what's causing this noise which happened twice in a short span last night.

Cap

The sound appears to be connected to the upstairs toilet after all. So we're having it changed. It's over 20 years old and we've got our money's worth from it. In the meantime, we've gotten rid of the humming in the pipes by turning off the main downstairs and opening up all the taps in the house, then starting from the bottom to the top of the house, turning them off one by one. Haven't heard the humming in three or four days. Now if I can just figure out why the furnace fan is rattling....:)

Cap

Whenever the water is shut off and then restored, it can dislodge crud that has accumulated in the pipes. This can cause a seal or valve to become contaminated and no longer shut off properly. An old toilet valve can easily have that problem. Sometimes, just the action of using the thing will flush out the crud and restore operations. Sometimes, you need to replace a seal. On an old toilet, the fill valve probably was no longer shutting of completely, and that slow leak can cause the seal to vibrate in the water stream. If you'd looked into that toilet, you may have noticed that the water level was up to the overflow, and the tank would likely appear to be cold from the constantly running water, even at a low flow...it doesn't have time to warm to room temp.

Water valves will purge the air out when you open them up...it doesn't really matter, other than the surprise, it rarely causes problems, but will happen each time the water is shut off, a valve opened to let in air, then the water is restored. IOW, it's normal, not a problem, and needs no special action on your part.
Now, a 20-year old toilet probably uses a lot more water than the new ones, and is likely to work better without needing plunging, but some of that is dependent on what you replace it with...not all toilets are created equal!