Water Leaking from T and P Valve

Norman Zarr, who lives in glorious Asheville, NC home of the Biltmore Estate and the Grove Park Inn, has water dripping from his T and P valve on his water heater.

Here's what he told me:

"I get  water dripping from my pressure/temperature overflow valve on my water heater.  What are the possible causes?

I have a pressure regulator on the incoming line to the house and an water expansion tank on the cold  water feed to the water heater tank."

Norman, there are three possible causes:

• Increased water main pressure from your city water mains (very low probability)
• Failed expansion tank (high probability)
• Failed pressure regulator valve (low probability)

I would change out the expansion tank that's adjacent to the water heater. When you do this, if there's not an in-line ball valve shut-off valve, install one. This makes it so easy to install new expansion tanks in the future.