For most homes, 80 psi (pounds per square inch) is the right thing to do. If the water pressure is higher than 100 psi, it's too much. A secondary problem is thermal expansion. This occurs when a water heater is turned on to maintain the temperature even though hot water is not being used.
If the pressure isn't acceptable, it might be worth talking to a plumber about installing a global valve to regulate water pressure. Now I know how to check if there is no water pressure, but I'm not sure what pressure I should set the expansion tank to without water pressure. If the system is closed, perhaps as a result of a check valve, a pressure reducer, or a backflow prevention device, then as the water heats up and expands, it has nowhere to go and that causes pressure peaks. The ideal healthy pressure of your plumbing system and appliances is between 40 and 60 PSI, and building codes in most areas specify that the water pressure is less than 80.
A dial allows you to adjust the pressure between 45 and 55 psi while the tank stores additional pressurized water to reduce how often the pump must operate. I also have a pressure relief tank next to the water heater and that's where I have a water pressure gauge. Therefore, opening a faucet with a water pressure of 150 psi can consume two or three times more water than if the pressure were just 50 psi. The easiest way to check the water pressure in your home is to check the incoming pressure from the municipal pipes.
I have read the instructions, so I know that I have to remove all the pressure from the water, but the instructions are first for a new installation, but I still have the pressure that should be on the outside of the bladder without water pressure. You can try other faucets in the house using the same method to help locate pressure problems inside the house once you have an idea of the initial nominal pressure.