Let me say first off, this BBS is great! The questions are very typical, and the answers are polite and helpful.

On to my problem. The hot water pressure/flow at our tub/shower is lower than I think it ought to be. It started as almost a trickle, and is now better (thanks to this BBS), but is still a fraction (maybe 1/4 or less) of the cold water, which on full blast is so strong the drain has a hard time keeping up with it.

Before posting this, here's what I did:
1. Opened the faucet on the hot water heater. We have very soft water, so I got a little brown rusty water at first, then it ran clear. I probably ran 4-5 gallons out of it. (This hadn't been done since we bought the house 12 years ago.)
2. Turned off the hot water pressure at the heater's cold-water inlet. Removed the hot water stem and washer assembly on the tub's two-handle faucet. Took the opportunity to fix a long-standing leak by replacing the washer, which had about 1/4 of the circle missing. Turned the heater's cold-water inlet back on, so that hot water came gushing out of the valve body. Let it run for about 15 minutes to clear out any junk in the line.
3. Turned off the hot water pressure again, replaced the hot water stem and wacher assembly, and turned on the hot water pressure.

We now have about twice the hot water flow/pressure that we'd had before, which is definitely a step up. Nearby sink faucets seem to have pretty good hot water flow.

Any further suggestions on how to improve the hot water flow at the tub would be greatly appreciated. For a little background, this house dates back to some time in the fifties (it's not clear since the town records were lost in a flood a number of years ago), and I suspect the water pipers are galvanized.

Galvanized pipes can be a big problem with hard water. It sounds like yours is soft enough, that they are mostly OK. I think you need to continue going further than you have. You may have a mineral build up between the sink and the tub. Take apart everything you can between them. Remove any junk you can see. Run a coat hanger as far back in as you can, trying to knock loose any deposits. Flush out everything, and see if it helps.

You could have a clogged pipe buried in a wall or under the floor. Going after them could be more bother than it is worth. Drywall isn't too bad to cut into and repair, but tile walls or the floor could be a major project.

1st post (read your prob and had something to add... hopefully usefull)

Do you by any chance have a single lever/dial type control for your tub/shower... the type that has one of those pressure balance cartridges in it?

I lived in a 2bdrm condo where 2nd bathroom received limited use and the super had to come and replace the cartridge about every 4-6 months due to pressure problems... similarly, I believe a number of the manufacturers also have notched settings on the cartridges themselves to further control hot water flow... could also be sediment clogging inlet to it... worth checking out if that's your setup though (majority have lifetime replacement anyway... just get another once it's apart)

Good luck... moo

Good morning Bob, Your hot water problem was caused by mineral buildup in the heater. You have flushed out the hot water supply line. You should flush the heater out on a regular basis also. Let me show you how.
If you do not flush,(not drain) your heater on a regular basis it will build up mineral on the bottom of the tank. 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) and some white grains,(lime or calcium carbonate). The whole thing shouldn't take more then a few minutes. Don't forget to flush it out every month. Your heater will thank you for it. You might want to consider cleaning the screens on your areators if you have a high mineral buildup. Good luck, Tom

I thank every person for their suggestions. Now I will find a plummer, because I do not know how to fix it myself, and I do believe I have a leek in my pipes.

Thank you from New Jersey

When the hot side pressure is bad in all of the house it is going to be a problem with the hot water heater outlet usually. If it is just bad at one location especially when it is the shower and your shower is a single handle unit, it is the cartridge in the valve body. It is a very common problem with Moen valves as well. Simply replace cartridge by removing trim then cartridge and install new one. They should carry your part at home depot. You will be back in business.
If it is all over the house try replacing the hot side nipple and supply line coming out of heater,that will usually take care of it. If not it could be build up in piping and you might need a repipe.

More about this in one of my blog articles:

http://aw-sons.com/slow-hot-water-flow-in-shower/