I believe I have a slab leak. Why are the spots that are warm later in the day after using the hot water warm in the early am?

I believe I have a slab leak. Why are the warm spot in my floor cool in the early am before any water is used?

Hi gutzwa

Are u on city water or well?

If city water, with nothing running check to see if meter is moving.

If well water, with nothing running watch pressure gauge for movement downward.

If no sign of water movement, then it probably is
Heat radiation from the hot water line in concrete.

Let us know outcome after checking. If there is a problem we will help u fix it.

Good luck

Chuck

City
I have already determined the meter is running with no water being used, a plumber has detected the leak from my water heater to my kitchen sink, the furthest point in my home. I am confused as to why the floor is cool when there has been no water use if it is truly a leak. Also, the first warm spot was in my bathroom several months ago and within the past few weeks the warm spots are in almost every in my house.

A warm spot on a slab is a telltail sign of a leaking hot supply line. They leak less during use than they do when unused, more pressure and volume are available to the leaking pipe.

A warm spot on a slab is a telltail sign of a leaking hot supply line. They leak less during use than they do when unused, more pressure and volume are available to the leaking pipe.

If they leak less when not used why is there more warmth when they are being used?
Thanks

You seem to have a double post going on here so we'll see about blending all the answers. The pipe gets hotter when you draw a lot of hot water to a fixture. Just like when you put your hand under the faucet and turn on the hot, it takes a few moments for the hot yo reach you. Also it takes time for the heat to be absorbed through the concrete

I see. Why did the warm spot only appear in one room initially and now is in all rooms?

Thanks

I have already determined the meter is running with no water being used, a plumber has detected the leak from my water heater to my kitchen sink,
You may have other questions but for right now this should be your main concern.
You already know that you have a leak. (Creahands gave you a excellent answer on how to detect if you , in fact , have a leak. The plumber checked and verified it.
So now you have to pin point it;.You can't go by the hot spots because water, like electricity, will seek the path of least resistance. This means that the leak can be in one spot and the hot spot some distance away.
I live in a area where all out buildings are on slabs so I've had this many times. Our usual way is to call in a leak detection service such as Sleuth. They will detect the exact position of the leak. Take up the slab, bag the dirt and bare the leak. All we have to do is drain the system, replacethe bad piece of pipe and patch the slab.
Another method would be if the plumber knew the exact pipe that was leaking the fixture it serviced and the location of the manifold that supplied it he could cut the line at the manifold, cap it off and look a new line up in the attic and drop down through the wall to pick up the fixture. Good luck and let me know how you make out. Tom

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