Your water heater s relief valve can start leaking for one of two reasons.
Water heater pop off valve leaking.
There is the off chance the gauge doesn t work.
Most hardware stores sell a 0 200 psi gauge that screws onto any hose thread like the drain of the water heater for around 15.
The second reason a water heater relief valve leaks is the water has gotten too hot if the temperature of the water in the water heater reaches above 210 degrees f the relief valve will leak or even blow off this is why the outlet of the relief valve must be piped to about 6 inches from the ground you would not want to get a blast of 210 degree f water in the face.
Close the cold water cut off valve going into the water heater.
These valves may look identical but they re set to go off at 30 psi not 150 psi.
Watch the gauge and see if while heating the pressure rises well above 45 psi.
Either the valve was triggered to open because of excessive temperature or pressure or the valve itself is faulty.
Open the valve at the bottom and the pressure relief valve for a minute to drain a little.
If a new tprv is properly installed and it still leaks you probably have a pressure problem.
My hot water heater is leaking from the pop off valve i have replaced it several times and now i have a new heater and guess what it is leaking through the pop off valve.
If a pressure relief valve for a boiler is accidentally installed on a water heater it will leak like crazy from the start.
In the first case the valve will drain water out of the discharge pipe as explained above.
If you do try to fix it here are the basic steps involved.
If a pressure relief valve for a boiler is accidentally installed on a water heater it will leak like crazy from the start.
These valves may look identical but they re set to go off at 30 psi.
I imagine it will and you ll know for certain why the relief valve is leaking yours larry ps.
I have had 4 different plumbers check this out they put a new regulator at the water meter turned the temp of the water down replaced every thing in the old heater.
Turn off the power to the leaking water heater.