water pressure

Hello, I just replaced my defective water regulator with a Watts 25AUB-Z3 with a built in bypass valve for thermal expansion. I now notice that after the gas water heater shuts off, the hot or cold faucet is harder to open initially. Once the faucet is open, the pressure is higher for a moment and then the pressure is back to normal. I have checked the t&p valve on the hot water heater and it is secure so I guess the pressure is not high enough to lift it. The original water regulator was defective causing the t&p to lift. Should I be concerned about this pressure spike?

At what pressure does the bypass valve open? My guess is that it is higher than your setting on the PRV, but lower than the T&P valve. This would prevent the valve from dripping, but the pressure would still be higher than you might want. An expansion tank will keep the pressure more in line constantly, even if it is not required.

And and expansion tank is cheap and easy to install.

The bypass only is effective if the house side pressure rise above street pressure. If street pressure is higher than 150, the TP will be the first relief. Get an expansion tank.