Water Shut Off But I Hear It Flowing

[ttibsen]

So we had a new 60 gal. GSW hot water tank installed 2 weeks ago and it's working just fine. However, sometimes when I'm down in the basement, I can definitely hear water flowing in or out of the tank (I'm not sure which) through the pipes at the top of the tank (one cold, one hot - again, I can't tell which one the water is flowing through). This is happening even when there's nothing in the house that's using water. Then suddenly the flow will stop and all is quiet. Another odd thing is that the blue copper pipe feels hot. Should it? I thought this is the pipe that feeds cold water to the tank so shouldn't it be cold?

 

[Bannerman]

I can't tell which one the water is flowing through)

If hot water is flowing from the tank, then cold water will be flowing into the tank. The only time cold water could enter the tank with no hot water flowing to home fixtures would be if there was a leak from the tank, or if the T&P valve is allowing water to exit, both of which I would anticipate would be noticed by you.

The T&P valve is a safety device which will normally only open if the internal temperature or pressure of the water is higher than the valve's release settings (usually 150 psi and 210 F). The T&P valve is often located at the side of the tank near the top. It will typically have a plastic pipe threaded into it which will direct any discharge down to the floor, or the pipe maybe extended to a floor drain if one is located nearby.

the blue copper pipe feels hot.

When no hot water has been used for some time, the cold inlet pipe will usually slowly become warm as the hot water within the WH will transfer heat through conduction and convection.

Also, when cold water is heated, it will expand. As water cannot be compressed, the expansion will need to flow somewhere so with no hot water being consumed, the expansion will flow backward through the cold water inlet to be absorbed by either the municipal distribution system if on city water with no backflow prevention, or into an expansion tank if there is backflow prevention. If your water source is your own well, then the expansion will be typically absorbed by the pressure tank.

I can definitely hear water flowing in or out of the tank

Is your home connected directly to any other homes?

I reside in an end unit townhouse so I am directly connected to 1 neighbour. I can occasionally hear my neighbour's water flowing, which I sometimes think is water running in my home.

I can also sometimes hear water within my gas WH making a slight hissing sound while the burner is operating and water is being heated.

 

[Sponsor]

 

[WorthFlorida]

So we had a new 60 gal. GSW hot water tank installed 2 weeks ago and it's working just fine......

Did you install an expansion tank? All water heater manufacturers require it for warranty and many cities codes have change that requires. Very cold water in your part of the country needs to expand quite a lot when it is heated and it has to go somewhere. An expansion tank will greatly extend the life of the WH.

 

[Terry]

Do you have a recirc line on a timer for your water heater?
Do you have a toilet in the home that is refilling often on it's own?

 

[ttibsen]

Thanks so much for that detailed response. We’re not connected to any other homes as we live in a single family detached house. Our tank, unlike yours, is electrical but could it be that the noise that I’m hearing is due, not to any water flow at all, but to the heating element being on? Then, when the heating element goes off, there’s no sound? This could explain


<< then suddenly the flow will stop and all is quiet >>



Now that I think about it, when heating water in a pot, you can hear it as it heats up so maybe it’s the sound of water being heated in the tank that we hear?



an expansion tank? - not as far as I know - all that’s visible in the basement is the hot water tank itself. I presume that if there were an expansion tank it would be of a size that I could see.



recirc line on a timer - definitely not



toilet refilling on its own - definitely not

 

[Phog]

I had the same mystery with my hot water tank years ago. When I was in the basement one day home alone I noticed slight hissing like someone had a faucet open upstairs, even though no one else was there. Checked every fixture and found nothing. By the time I was done looking around & back downstairs the sound was gone, though I could feel warmth on the hot water tank outlet pipe. Over the next week or two this would happen sometimes but then mysteriously go away other times. One day I decided to get to the bottom of it. I shut off the valve to the water heater. The sound remained. Then I shut off the service valve to the house. The sound remained again. Then I realized that it had to be the water boiling inside the tank. So I shut off the electric breaker. The sound almost immediately stopped. And came back again after I turned the breaker back on. I bet you're noticing the same thing. The warm outlet pipe from the tank is caused by convection and is a very small energy efficiency loss that can be solved with heat trap fittings. (Or left alone & it will cost you an extra $5 per year or something like that)

 

[Jadnashua]

If you think there's some water flowing, check the water meter while that is happening.

 

[ttibsen]

<< Then I realized that it had to be the water boiling inside the tank. So I shut off the electric breaker. The sound almost immediately stopped. And came back again after I turned the breaker back on. I bet you're noticing the same thing. >>
EUREKA!!! That indeed was it! I made certain that not a tap was flowing, no toilet tanks filling, no garden sprinklers on and then went down to the basement where it was utterly silent except for the sound emanating from the tank which I previously attributed to water flow through the pipes. The electrical box is only 20 feet away and when I flipped the heater switch - silence - turn it back on - the sound comes back! So yes, your bet was correct - I had the same problem as you. As I said in my original posting, we had no issues at all with the tank since it was installed a couple of weeks ago but this noise factor continued to nag at us. It is somewhat disconcerting to hear and not know what is going on. So that's a big relief to have diagnosed the problem and know that all is working as it should. Thanks so much Phog and all the others who took the effort to share their views on the problem. Great forum - very pleasant first time experience!

 

[Jadnashua]

My guess is that you have hard water. This will cause mineral deposits. When the elements are off, water can seep into small pockets of the mineral deposits. When they heat up, that trapped water can overheat to steam, and 'pop' out, making noise. Normally, there's not much of a sound from a new, clean element. Convection of the water just moves the warmer water up and out of the way, bringing in cooler water so the element itself doesn't get hot enough to flash any water to steam. Given the water under pressure, it has to get lots hotter than 212 to do that; way beyond the temperature of the rest of the water in the tank.

 

[ttibsen]

You are correct - the water in Whitehorse is very hard but I am guessing that in itself this isn's particularly hard on the tank as our old tank was good for 20 years before giving up the ghost.

 

[Jadnashua]

Heating the water will cause mineral deposits. That does two things:
- starts to decrease the overall volume of hot water the tank can hold
- slows the heating because of the insulation which can allow the element to get hotter. Normally, the element doesn't get hotter than the water surrounding it as that heated water just flows away from the element. If the minerals have insulated the element, what water may come into contact can see higher temperatures and can microboil...that can make some noise.

Because water is such a good conductor of heat, you can boil water in a paper cup. Now, it may burn off above the water line, but that's a different story!