Mysterious hot water leak

[ississauga]

I can hear water running in the drain in the basement even though there are no obvious leaks so I placed my hand above 'drain cover'? (is that what you called the 6 inch diameter metal cover with holes in it so that if the basement floods water will go away thru that?) and I can feel its warm water thats leaking.

So I l ifted the 'drain cover'and discovered that there is a half inch diameter plastic pipe embedded in the concrete and the hot water is dripping into the drain from this pipe. But where is this pipe getting this hot water from?

When I shut off the cold water supply to the (natural gas) water tank (there is no tap to control the hot water existing the water tank) the leak stops.

Any ideas, suggestions on where this leak originate from and how to fix it?

[Tony Hwang]

Hi, Could be pressure relief valve drain? How about lowering the water temp for temporary. Tony

[SJF]

Looks like you need to replace the relief valve.

SJF

[HeatMan]

Do you have any water pipes in the basement slab?

Others have said it could be the T&P valve from the water heater. That's a possibility.

[Joe Bobst]

If the problem is the pressure relief valve (likely), you may need to replace the valve or add an expansion tank or both. HTH

Joe