Moderator Post (s) for this thread: >Low flowbyBillhart on 01/11/2008
I seriously doubt that they added anything to system.
There are no common parts that would do what you say (if they aren't damaged).
And to rig up something would be too much work.
If the riser is a flexable "hose" (covered with braided stainless steel is the best) then turn off the stop valve and remove the connection at the bottom of the faucet. If you don't have a flexable hose replace what you have with fleable hose.
Then put the faucet end in a bucket and turn on the stop valve. If you don't have good flow then the problem is in the riser (unless you just replaced it) or the stop valve.
To replace the stop valve you will need to shut of the water. There maybe a shut off in the apartment, but there might only be one for the building.
If you get full flow out of the riser then the problem is in the faucet.
The easiest thing to try is to back flush the faucet.
With the cold water riser off, AND BUCKET UNDER WHERE THE COLDER RISER CONNECTS TO THE FAUCET, turn on the faucet cold water and then turn on the faucet hot water.
You might need to hold you hand over the spout.
You will probably need someone to hold the buck and keep you had on the hot water faucet to quickly turn it back off.
But again, the first think is to check and see if the stop valve is fully open.