How do you get air out of water pipes to restore pressure in new lines?
It sounds like a valve is not fully open. Sometimes these things are sticky, and you think you’ve gotten them opened and they are not. There is absolutely nothing you have to do to “restore pressure” other than open valves. If you have cold water pressure, opening the valves will restore hot water pressure. In an unusual case, the shut-off portion of the valve can break loose from the handwheel. The valve cannot be opened although the handle will turn nicely. If you have a valve that just continues to turn and turn in the counterclockwise direction, you would have a valve where the stem has broken loose from the valve. You would need to block in your water supply and disassemble that valve to determine what the problem is with the valve. For starters though I’d assume that a valve was not fully open and go and open them. Remember, clockwise-closed, so you want to turn them counter clockwise to open them. MAKE SURE YOU CHECK ALL VALVES LEADING TO THE FAUCET THAT LACKS PRESSURE.
