ok, I can't figure out what's going on with my water pressure. It was fine before Ichsnged out my water heater. I went fom a 75 gallon electric to a 75 gallon natural gas. I haven't added any new showers, fuacets, toilets, or anything like that. Sense the change, when I use the shower in the basement I have little to no water pressure in the basement and no hot water pressure anywhere in the house. The water pressure throughout my house is perfect unless I'm using my basemen shower. I have other water hook-ups in the basement, such as washing machines, sinks, and toilets, but my water pressure doesn't seem to be effected when thee are running. It's only the shower. I took the shower head off to look for some sort of blockage and I have none in the shower. I didn't think a blockage would be the problem sense I lose water pressure throughout my houe when I use the shower. Do you know what's wrong. No one seems to have the answer for me. Your help wouldbe much appreciated. Sincerely, Anthony

Have you checked all the shut-off valves at the water heater to be sure they are all fully open?

Also check the main shut off valve. If the house uses the old style gate valves that could be the issue. Quite often they fail and even if you think you opened up the valve all the way its stuck half way.
But like Richard said. Check the shut off valve on the hot water heater. FYI there also should be only 1 valve on the top of the heater.

Also what size are the pipes going to and from the hot water heater? Half inch or 3/4 inch.
I had a client not to long ago that did his own plumbing and used way to much solder on one fitting and plugged off almost all of the pipe with the solder as it leaked into the pipe as he joined it.