Is this what knocking pipes sound like?

Sounds like you need a bigger problem to take your mind off the small ones.

Yeah, I'm guessing you won't see the humor.

Just a few hundred years ago, you'd be very happy the sound wasn't a bear trying to knock down your front door.

I was going to mention the same thing as one possible cause of the "knocking" sound.

The flapper in the toilet could be leaking slowly and/or the flush valve could be causing the knock. The OP could try replacing the flapper in the toilet as a first step, or replace the flapper and the flush valve. Or, shut off the main valve and see if the noise goes away with the main valve shut off. Of course, that would be a pain because he would have to turn the main valve back on every time he wanted to use water for anything and then turn it back off and wait some more to see if he hears any knock with the main valve off.

Someone wants to remove the duct from the ceiling and replace it with a "plastic" one? I never heard of a plastic heating/cooling duct, but maybe there is such a thing?

Did you post about the ceiling duct noise here in the past? I remember someone posting about that, and I think he was from my general area (South Jersey).

I have a tenant who described the same kind of sound, and he is fairly knowledgeable about this kind of stuff (he does handyman/construction-type work). He thought it was possibly coming from the basement or in a wall. In his case, he could usually create the sound by flushing the toilet and then waiting until after it fully re-filled and then he would hear the noise. It also happened at other times without him flushing the toilet. I suggested maybe the toilet flapper and flush valve. I bought them and I was going to do the replacement but he said he would just switch them out on his own (he's a great tenant). That fixed it.

Interesting (both posts). Thanks.

We don't know anything about the house. Is there a basement or a crawl spa ce. Is it a 1-story plus attic or a 2-story plus attic, or two-story witho ut an attic.

If the noise occurs about every hour, go to the basement or wherever the OP thinks the noise is coming from and sit down and read a good book. A leak y toilet flapper valve is easy to find, just shut the water off at that toi let, flush it so there is no pressure in the feed line, and see if the nois e stops. If it doesn't then that toilet is not a problem, and go on to a s econd and or a third toilet and repeat the test.

OP thinks the noise is coming from and sit down and read a good book. A le aky toilet flapper valve is easy to find, just shut the water off at that t oilet, flush it so there is no pressure in the feed line, and see if the no ise stops. If it doesn't then that toilet is not a problem, and go on to a second and or a third toilet and repeat the test.

Yes, it sounds like this is the OPs problem. Happens in my house too, toil et refills a little bit about once an hour and it makes a quiet little boom sound when the water shuts off. I really should replace the flapper valve .

Mark

What is it that is making the "boom" sound? Is it hard on the pipes?

he OP thinks the noise is coming from and sit down and read a good book. A leaky toilet flapper valve is easy to find, just shut the water off at tha t toilet, flush it so there is no pressure in the feed line, and see if the noise stops. If it doesn't then that toilet is not a problem, and go on t o a second and or a third toilet and repeat the test.

toilet refills a little bit about once an hour and it makes a quiet little boom sound when the water shuts off. I really should replace the flapper v alve.

The toilet valve is the type that the water runs until the float gets to th e desired level and then shuts off suddenly (instead of gradually less and less). This cause a noise in the pipes. I mean if you are in a quiet house you will hear the sound. If someone was turning off a faucet at the same time, you would think nothing of it, but when it happens in the middle of t he night when all else is quiet, it does catch attention. In my case it is not a loud boom, just a knock that you can easily hear. And it is from th e toilet tank topping itself off due to a slightly leaky flapper.

Mark

Thank you for your reply. I have encountered similar sounds before. Now have a basis for how to proceed with them in the future. Ignoring sounds (and hoping they go away) is less noble!

Bill

Good idea. That beats the idea that I proposed earlier about turning off the main water supply valve. Duh..., just shutting off the valve to the toilet makes more sense.

I can relate to this completely. Had on going problems with pipes noise and was woken at 4 am with what sounded like a sonic boom! Heating had gone of f by 6.30pm the previous night, no other taps or water running. Frightened the life out of me and as I'm in a mid terraced house God knows what the ne ighbours thought! It's making me ill, had three companies round but of cour se never makes any sounds when they come.