Just installed a new electric hot water heater. Same capasity as the old one.
Water pressure is fine on ground level, but the upstairs shower is very weak now!
The temp on the heater is set at 120. Will turning it up increase pressure? It will increase pressure in the tank right? That should increase the pressure in the hot water lines I would think.
Just thought I would ask before messing with the settings.

Copper pipes in home.

Is it just the shower up stairs or areother 2nd floor fixture low too? "will turning it up increase pressure? it will increase pressure in the tank right" if you mean turning up the heat then no and no. First off you probably can't go higher than 120 to begin with but that is temp, nothing at all to do with volume/pressure

As ballengerb1 says, don't increase the temp to increase pressure. Most likely if its just the shower that has low hot pressure, some debrees broke loose in the piping during w/h change out. Them debrees most likely got caught up in the shower cartridge. Turn the water off to the house, dissasemble the cartridge/s in the shower and clean them. While they are removed, turn the water back on for a few seconds to flush the supply lines, then reasemble the valve. Take precautions to prevent water from making a huge mess while flushing the supply lines. Good luck and please let us know how things work out.