Customer called in about having low water pressure on the hot side. Also water heater making high pitch noises. Upon arrival, customer mentioned that after installing water heater back in October, water heater would make weird high pitch noise and now hardly any water comes out of any fixture in the home on the hot side. We did install new water heater along with new prv and main shut off valve. Tested different fixtures and water pressure would come to a stop after a couple minutes. Tried to drain water heater and got same results. Informed customer that ball valve may be bad. Customer agreed to replace ball valve. After replacing ball valve, still got same results. After evaluating entire system determined that prv is bad. Due to us installing it few months ago, this would fall under warranty. Went ahead and replaced prv and water pressure is now 75psi for whole house and hot water working again.