Check the inlet valve to H/W tank. make sure it's full on. If still no hot water anywhere you need to call a plumber, you have a weird problem.
House pressure, 75 PSI maximum.
House water pressure should be around 50-60 psi.
No and yes. No, you won't get more water pressure. To do that you'll need to find out why the water pressure is low. Perhaps flow restriction, perhaps a poorly adjusted water pressure regulator, perhaps low pressure from the well/city water. But an additional water heater will certainly give you more hot water. It would be like putting in a LARGER water heater. In most cities the water pressure required is about 20 PSI. Small city's do not add pressure pumps to their system but use a gravity supply. That is why most places there is a pressure problem either build their water tanks taller or erect them on a hill.
One of the valves that you closed while hooking up the hot water to the sink was probably an old gate valve... It broke and did not fully re-open.
There is usually a main water valve that comes into the house, locate this valve and turn it down. Installing a pressure reducing valve after water main valve will allow for adjustment of water pressure to proper setting.
House pressure, 75 PSI maximum.
Pressure is the same whether hot or cold.
You may have a restriction in your hot water heater exit pipes. There may be corrosion. How old is the house and how old is the hot water heater? What type of pipe is there going out of the hot water heater? You need to know this to fix the problem yourself without hiring a plumber.
A mega-flow system is simply hot water stored under a certain pressure. The idea is to give one the same pressure throughout the house. This is a good choice of a boiler if one has high hot water demand.
Hot water does exert pressure, but the main thing is that it creates steam if hot enough, and that is often used to run machines that require pressure.
House water pressure should be around 50-60 psi.
My guess is that the hot water heater is installed downstream from a pressure reducer to limit the maximum water pressure that the water heater is exposed to.
If you have a leak on the hot water somewhere in the house and the water input into the tank is not running, the tank will lose it's water. And if it is an electric tank, the elements will burn out. Gas hot water tank should be no problem. Pressure valve does not have to be open.
Replace the tub faucet.
the water pressure of the sunlight zone is very hot....
in Lower pressure water does not have to get as hot to boil
yes and no. usually you want your psi between 65 and 80. otherwise it will cause you problems!!