My bathroom sink is making very loud banging sound when running hot water. The cold water pipe/faucet is fine though. It doesn't seem to matter whether I open the hot water faucet fast or slow, it'll make this banging noise. It seems the banging noise is random but one thing I'm certain is that the noise does not occur when the water is cold on the hot side faucet. Any help is much appreciated.

 

Could be air trapped air in the pipe. But that will usually purge itself. If you have access to the bare pipes, running the hot water, grab the pipe and feel for vibration and if holding tight eliminates it then securing it will resolve the problem.
How close is this particular faucet to the hot water tank? Is the pipe touching any other item such as other piping, or ductwork or even a rafter or stud without being clamped to it?

 

Thanks for the response. Actually when the hammering starts, the water flowing through the faucet is actually slows down. So, it's not only is the noise from the pipe but the flow of the water is slow down significantly. This noise just starts about 2-3 months ago. When we first purchased the house, we've never experienced it.

 

That could be a sign of a faulty faucet washer, stem, or cartridge. What brand is the faucet? How old is it? You might want to upgrade to a Moen or Delta.

 

I agree with Norm. Usually that jackhammering noise is the result of a worn or loose washer somewhere near the fixture you're using. Could be in the faucet itself, or the stop under the sink. Could be elsewhere too, but it would then likely affect other fixtures also.

In most cases, it happens when the water flow is less than full-open... but can happen anytime.
One way to test would be to close the under-sink stop by a turn or so and see if that changes anything. Might get better or worse, but the change will help narrow it down. Then, depending on the valve or faucet, it can either be a washer replacement, or a valve/faucet replacement.

 

Thanks, everyone! I'll give that suggestion a try tonight. It is a Moen brand and I've purchased it about 3-4 years ago. However, it was one of those discontinue product line from Moen when I purchased it. I wanted to match my other bathroom.

 

The outside style may differ but the internal guts will be up to date. Call them for replacement parts. They should be free.

 

Okay, I finally got the time to remove the hot side handle and this is what it looks like. I don't see anything wrong with it. If I slowly turn this plastic red thing here by hand, it'll make the hammering/banging sound as well. Other suggestions?

 

Your dealing with tolerances that you can't see. Call Delta (or is it MOEN) and get a replacement cartridge. It should be free or buy one at the local home improvement store.

 

One additional thing I did was, while it's making the banging noise with the handle turn wide open and water flowing, I slowly turn the valve of the water supply off. As soon as the water is off while the handle is still wide open, there is no banging noise but as soon I as slowly turn the value of the water supply line back on, the banging noise comes back. Any idea where the cause may be at? Thanks!

 

Thanks, Norm201! I will try to get a replacement from Moen and see it helps.

 

Yes, your supply line valve is faulty. Replace it!

 

Norm201, you mean the water supply line from the valve to the turning handle? Replace that part?

 

Yes. The shut-off valve. What I call the isolation valve. You might be able to fix it rather than replace it. Depends if a cheapy or an older repairable type. You'll need to turn off the water main for the whole house.

Edit...not the supply line itself, but you can if you want.

 

The line with the red X or the green X?

 

By how much do you need to turn that valve off? By throttling back can you still get good flow? If it's only a little bit, you can cheat and let it go for awhile.

 

Okay, got it. Thanks, Norm201! I will do that quick and see if it helps.

 

The Green X

 

The banging will only stop when it's fully turned off. Even if it's just small drips, it will still making small banging noise.

 

You'll need to find out if that valve is soldered on or screwed on. And how much of the copper pipe sticks out from the wall. They look like cheapy ones not repairable. But I'm not sure from the pic.

 

Be aware it still may be the faucet. The force of the flow is what is making the parts vibrate. It could be the shut off valve or the faucet or both.

 

It's not solder. I assumed I do counter clockwise to loosen, right?

 

Since the shutoff value is readily available at my home center, I'll replace that first. If the noise continues, I will try to get a replacement from Moen.

 

Righty titghty, lefty loosey.

edit...when you shut off the water to the whole house, be sure to open a faucet to relieve pressure and drain the lines. Open the lowest and the highest.