I have plenty of cold water pressure, but very little hot water pressure in all faucets, and all valves are wide open, any suggestions?

i have plenty of cold water pressure, but very little hot water pressure in all faucets, and all valves are wide open, any suggestions?

Yes! Mineral build-up in the water heater that has been sucked into the nipple coming out of the hot water side of the tank. IUf it's not the nipple then remove the cartridge from a faucet and turn the water on to flush out the supply. If you don't flush your heater on a regular maintenance schedule let me show you how.
For long life and fewer troubles you should keep your heater clear of mineral build-up by flushing on a regular schedule. Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run until the water runs clear. You will see a spurt of red,(rust) followed by white grains,(lime or calcium carbonate). This shouldn't take more then a few minutes. Do this monthly to keep it clear. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps, Tom

Also just for the heck of it, if you have a shut off on the hot water heater, make sure it did not get closed part of the way.

I had a similar issue in a rental house and worked about 5 hours before I discovered someone has shut the water partially off to the heater.

Yes Chuck, Monday night I told the assistant minister at church that it was OK to turn up the thermostat for her office, and showed her how.

By the way, I have read here that code forbids shutoffs on the outlet of a hot water tank. Doesn't stop me from having one.