Low Pressure in Bath/ Shower American Standard Colony Two Handle 3275505.002

[handybroz]

Got an interesting one here. I was working on a bath/ shower with a American Standard two handle (3275505.002) with low water pressure and have tried everything I can think of to get pressure back. At first I thought easy fix swap about the valve cartridges and flush multiple times and I should be good to go. That did not work. Water pressure increased slightly. I know that there is plenty of water pressure from the hot and cold supply as water shot across the tub on both hot and cold with the valves out. I thought the pipe going to the tub faucet might be clogged with rust but it can't be. I pulled the plunger for the shower head and pressure built slowly and once pressure had built I pushed the plunger down and water came flowing out quickly which tells me this pipe is fine. Water flows equally whether just cold is on or just hot or both. Does this mean there is a clog somewhere in the rough in and if so what is the remedy.

 

[havasu]

Is it possible one of the valves outside was not fully opened? Is the plumbing galvanized by chance?

 

[handybroz]

Is it possible one of the valves outside was not fully opened? Is the plumbing galvanized by chance?

Is it possible one of the valves outside was not fully opened? Is the plumbing galvanized by chance?

All valves are open from the main to the faucet. Yes the pipes are galvanized. However when the valves are out the water pressure coming out of the rough in shoots all the way to the other side of the tube on both cold and hot I have flushed and taken out the valves more times than I can count and they were never clogged and the amount of water coming out of the faucet from both sides did not change after regardless of which side was on. It seems the rough in is the problem, but I am not sure how.

 

[havasu]

Pull the shower head and verify there isn't chunks of rust clogging it up. This is very common, especially after opening and closing seldom used valves.