I've got a hot water leak under my c.1955 slab. My oil burner kickes on every 60-70 minutes and you can hear the pipes "whining" when you're in the bathroom. When I turn off the hot supply, the "whining" stops and the leak detector stops on the meter.
You can feel the warmth from the pipe's path under foot and it takes awhile for the slab to cool down once the water supply is cut. My question is: Does it stand to reason that the leaking area would be the first to get warm? I bought an infrared thermometer and I was hoping to pinpoint the leak site before I tear up my hardwood floor. There is absolutely no hint of moisture in the area I am targeting.
Since you can feel the path of the pipe once it heats up, try this. Turn the water back on but don't use any hot water for several hours. Feel for the warm path and where the path ends is probably where the leak is. (Hot water won't progress past that point when none is being used.)
When cleaning anything including baby diapers, it is better to sweep off or scrape off as much solid and semisolid material as you can first. (1) Less cleaning fluid or detergent needs to be used, (2) Less of a mushy mess which in turn means that bleaches or disinfectants will be more effective.