By reading and following manufacturers directions of course
You turn the PRV down to required pressure
I just had a home inspected, and the inspector measured the static water pressure at 115 psi. He noted that this pressure shouldn't be above 80 psi and recommended installing a pressure reducing or regulating valve to get the pressure down to 80 psi. He warned that too much pressure stresses pipes, fittings, and valves and can cause any of these to fail. Most solenoid valves on a washing machine or dish washer would not like to see over 80 psi Gage. other valves like faucets and boiler drains my leek sooner but will not be effected as much. The pressure relief valve on your water heater may exceed its 150 psi if heating from a cold take with out a domestic expansion tank, especially with existence of a check valve at the water meter.
50 psi
you can adjust the pressure. for example water boils at a higher temperature in a pressure cooker.
How to reduce your water pressure to your taps if you have a high mains pressure or an unvented cylinder such as a megaflow, boilermate ect. Reducing water pressure in your home can be done in several ways, my video demonstrates a few. Some people turn down the isolation valves or main stopcock which is not advisable, as it can produce noise, water hammer in pipes /taps and can damage the valves and stopcock.
Yes, like all other mechanical devices.
There are no pressure valves on a regular home hot water system. If you are meaning some kind of industrial application,then say what exactly it is.
If the pressure exceeds the normal rating of the fittings and valves.. Normally rated for 125 PSI
There is a bolt/screw that you turn on the top or bottom of the valve. If the pressure has decreased recently there may be issues that need to be addressed other then just increasing pressure...
Water not on at street 'city' valve, or other valves--after inside main valve--off.
Yes, add or remove water. Add to increase and remove to decrease. Use the autofeed valve to do this. Lifting the lever allows city water pressure into the system. Lowering the lever puts it back to its limiting setting. Most auto feed valves have a pin under the cap that can be adjusted by screwing in the top or unscrewing the top. This adjusts the preset pressure. Never go over 25 pounds or you will discharge the pressure relief valve.
the pressure depends on the well pressure tank and switch. It is normally between 30 and 70 psi in a domestic well system
Most thermostatic valves are only needed in a domestic water system that has a device to heat water (such as waterheater). These valves will control the set temperature of the valve and only allow the degrees of set temperature and colder. Example lets say you have a thermostatic shower valve with the cold side being 52 degrees F and the hot side 140 degrees F and the valve set at 120 F , this valve will only allow the max temp of 120 F out of the shower head but does not control any cooler temp only the max temp in which it is set. They also have thermostatic valves that control any temp but mostly for controlling hot water to prevent scalding. Pressure balanced valves will not control temperature only pressure and equals the same pressure from hot and cold sides.