2 different noises

[plessthanpointohfive]

Noise #1 is a knocking noise. It's not water hammer. It happens in only one of the second floor bathrooms and only when the hot water's been running a minute or two. The knocking noise continues for a little while after the water is shut off and then gradually fades away. What is causing this and how do I get it to quit?

Noise #2 is a grating noise somewhere in the main floor, in the same part of the house that has the kitchen. It happens every now and then throughout the day when no noticeable plumbing event is occuring (ie, no one's flushing a toilet, running the dishwasher or washing machine, no one's taking a bath, etc.). And it happens at any time of day or night. Could it be my 20 year old fridge (it has an ice maker)? Or is it something in my pipes?

House specs: 20 years old, copper pipes. Gas water heater.

Thanks a lot if you can help me!

Jen

 

[SteveW]

I'll take an amateur crack at these!

#1 sounds like the sound a hot-water pipe makes if it's rubbing against something (like a wooden stud) when it expands when it gets hot. If so, not much you can do except learn to live with it, or open up the wall/ceiling where the noise is coming from and free it up, or support it differently, etc.

#2 could be coming from a toilet -- sometimes a flapper valve will leak just a little, which in turn allows the fill valve to open up just a little, and this will sometimes cause a noise in the water system for no apparent reason. Older ballcocks (the ones with the big float on the end of a brass arm) seem to be the most susceptible. Next time the noise happens, go to each toilet in turn and lift up on the float (if you have 'em) and see if it goes away.

On the other hand, sometimes a closed water system (search on this to learn more) can generate weird noises when no water is being used. This requires an expansion tank to be added to the system to cure it. A quick test for this is to open a faucet when the noise is occuring -- it will immediately stop if this is the culprit.

 

[Sponsor]

 

[Terry]

Noise one, Your wastes lines can expand when hot water goes through them, and contract as they cool.
Sometimes you can make the holes bigger around the pipes so that dont' "grab".

Noise two, It's the ice maker. The grating could be the ice tray changing.
Or you could also install a hammer arrestor on the fill line if it's water hammer when it quits filling.

 

[plessthanpointohfive]

Thanks!

Thanks, Terry and Steve!

I'm relieved to hear these are really nothing serious. I sorta figured the knocking had to do with expansion but I wasn't sure.

I think Terry is right about the second noise. I think it is related to the old ice maker. I'll have to set up surveillance to check it out, along with the options that Steve offered.

Jen