Circulating Pump Help

[naicidrac]

I have lived in my house for about 1.5 years. I have a circulating pump on my water heater. It is set on a timer and it come on in the morning then shuts off. Then again it comes on in the evening, but shuts off around 10PM. Friday I stayed home from work and noticed in my master bathroom that the water was hot through the day. Normally I can certainly tell when the circulating pump turns off because it takes about 2.5 minutes for the hot water to get to the master bathroom. I checked the pump and it was in the off position on the timer and the timer was functioning properly. The guest bathroom did not have the quick hot water circulating to it as it took about 2.5 minutes to get there. I have unplugged the circulating pump all together and hot water still gets to the master bathroom instantly. Please tell me what is going on. In the past 1.5 years this has never happened. I can tell when the circulating pump is off because it takes a while to get to the master bathroom. For the past 24 hours I have had the circulating pump unplugged from AC power and my periodic checks show that the master bathroom is not affected, it still gets immediate hot water.

Thanks in advance,
Naicidrac

PS I just noticed that the floor right in front of the sink is very hot. I also noticed at the edge of the cabinet and the tile floor I see a bead of water. I think I have a small pin hold leak under my slab. What is the best path forward? Do I rent some infrared leak detection hardware or do I let a professional handle the detection. I think I could get an electric jackhammer and I have extra tile in the garage so that is not a problem. This is going to be a great learning experience. My question how is how to determine where the leak is?

 

[rfdevere]

1. Professional leak detection is worth it's weight in gold.

2. If its not leaking then the hot water can be circulating with thermal convection currents in the system - very common