On 5/23/17 1:14 PM, trader_4 wrote:
Here's a baffling problem. Over maybe the last year or so, the water
flow in the shower has decreased. It's happened slowly, so not sure
when it really started, but lately it's become a problem. It's not
the shower head, I removed it and the flow right out of the 1/2"
pipe from both the hot and cold are way below what they should be.
But here's the bizarre part. If I open just the cold all the way,
I get a flow of X, which is slow and way below what it should be.
If I open the hot, I get the same exact slow flow. If I open them
both, I still get exactly the same slow flow, ie no improvement.
To me that's weird, because it implies that there is some obstruction
after the two valves. But this is a Grohe faucet from 25 years ago,
ie it's not one with a tempering valve or anything fancy, so I
would assume the water just comes from each valve into a simple T
and is combined. So, I'm at a loss as to what could be wrong.
If it were debris, I could see it lodging before or in a valve,
but how could there be anything after the two valves?
Water pressure into the separate bathtub is fine, plenty of
water flow there, many times what's coming out of the shower.

Some cut.
Remove the shower head and run a fish tape down the pipe?