Water Heaters - Electric Water Heater-water line hissing noise

Here's a mysterious situation that has a number of us baffled.

Can a hot water plumbing line generate a hissing sound without a water leak being evident ? We have an electric hot water heater, about a month ago we noticed a hissing sound emanating from our guest bathroom. The ceramic tile floor next to a wall was slighly warm ,but no waterleaks were evident.

The water lines going to the bathroom all appear to be in the wall rather than under the foundation.
Cutting through the sheetrock to access the water leaks revealed no obvious leaks.

Turning off the hot water output from the Hot water heater ,eliminates the sound and the tile floor seems to gradually cool.


We live in a warm climate and 3 weeks ago we turned off the hot water for a couple of weeks. Last week we turned it back on , and the sound was gone and the floor stayed cool. A few days ago the climate got cooler (50-65 degrees) and the hissing sound came back and the floor is warmer. Turning off the hot water eliminates the situtation.


Anybody - any thoughts ?
Thanks

It does sound like a leak. It fits all the clues. Somewhere you need to be able to see the water that is leaking. It may only be a stain or damp wood but you should be able to see something if you dig deep enough.

Ken