low water pressure on hot water pipe

Hi...
Our house has a well with pretty hard water in it; we find stuff precipitating over time in the toilets, etc. We've got one pipe that's a particular problem - the hot water pipe to the shower in the downstairs bathroom. We don't use that shower often, but both the water pressure and the temperature of the water coming out seem to be falling off steeply over the last 5 or 6 months.
The pressure and temperature of the hot water in the sink in the same bathroom isn't anywhere near as bad.
Is there an easy way to tell if this is caused by mineral deposits, and if so where in the pipe? It's getting to the point where we couldn't expect any guests to use that bathroom anymore.
Thanks -Mark
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wrote:

My favorite suspect is the anti-scald valve getting munged up with crud.
Shut off the water to that branch, dip the shower-head in a gallon of cheap vinigar, and then open the waste-cock on that hot-water shutoff, to suck the vinegar backwards through the valve. Let it sit overnight, and then blow it clear and see if that helps.
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Thanks to both guys for responding. One thing that might also help the diagnosis is that this is a tub/shower combo, and the hot water flow is very diminished whether the water is coming out the tub nozzle or the shower head.
The other bit of info I should have mentioned is that if you're running just the cold water through, the pressure's okay.
Thanks -Mark
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Start by deliming the shower head in vinegar or CLR. or lime away. It may be all you need.
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