I had a plumber replace my hot water heater and fix a leaking faucet in the shower. The leaking shower faucet he said was due to pieces of the dip tube from the water heater. The water heater was replaced three months ago. This morning we had no hot water (very poor pressure) in the third floor bathrooms and the shower was leaking again. Pressure and hot water were fine on the first floor and in the basement. Plumber told me flush the pipes. If this happens. I can't remember the procedure. I know he would he turn the hot water off at the top of the hot water heater. I can't recall the next steps... but I recall he would run the cold water in the basement. The intent was for the cold water to run through the hot water pipes? Does this make any sense? What is the correct procedure?

Shower was leaking due to debris, this doesn't sound right. The drip tube particles could clog a faucet or shower head but not make it leak. 3 months may be too long but I'd call the plumber back. If he fixed an actual leak it should still be good. Maybe you have anew problem. Flush the lines doesn't require isolating the water heater, its new and no drip tube parts are there. Go to your tub facucet on the third floor and run both hot and cold for a few minutes. Might put a striner under the stream just to see if anything flushes. Do this then on the 2nd floor and then the 1st floor. This flushes the lines but particles can still be in cartridges or mixing valves from the previous drip tube problem. Each faucet that isn't working may need to be disassembled and cleaned out.