I have installed a new electric hot water heater and the pressure is low. Cold water pressure is fine. All water lines are new, its not sediment. What else could it be

It feels like pressure but this is actually a volume issue, a restriction somewhere. Who did the actual installation and is it soldered connections or threaded

My husband installed it and they are threaded connections

You will need to be a plumber detective starting with buying a pressure gauge and bib to install on your heaters drain. AMERICAN GRANBY COMPANY WTG300 WATER TEST GAUGE 300 - Tools - Plumbing Tools - Specialty Plumbing Tools With this we can start with the psi in the house by measuring the graden spigot outside and then the drain on the heater. Most homes are about 45 psi. Are you sure it is every hot faucet, shower and tub? Does your husband know what a heater trap is and does. AMERICAN GRANBY COMPANY WTG300 WATER TEST GAUGE 300 - Tools - Plumbing Tools - Specialty Plumbing Tools