Issue with hot water abruptly shutting off!

[Tcnjay]

Hi fellow Plumbers. I ran across an issue today that I am at a loss of words for. The issue is that half of the house has low hot water pressure and the other half is fine. This is also poly pipe.

When I turn on the hot water on the left side of the house (ie. kitchen sink, bathroom faucet, shower), it runs fine for about 7 seconds and then gets hit with a small shock and hot water flow is reduced to a third. The 7 seconds is further reduced if I keep turning it off and on. After a few immediate on and offs, it’s all low water pressure until leave it off for a few minutes.

The right side of the house works completely fine. It’s almost like something is clogged in the pipe on the left side. The water is all coming from the same water heater.

Any ideas!?!?! I’ve been pulling my hair out.

 

[Terry]

I had one job where rocks had gotten into the line from the landscapers opening the line outside. The wound up quite a few places in the home. I also had a home where a ball from the heat check nipple on the water heater had gone downstream and was make pressure on and off.
The job with the rocks, I wound up cutting the main line so that I could drain it outside to flush it, and setting it up so that I could use a hose to back flush it with. A washer valve with 1/2" threads on one side and hose threads allowed me to use a washer hose to connect to the garden hose on one side, and then a lav supply to attach to a shutoff where a faucet would normally be installed. This way I had complete control within my hands to turn water on and off remotely while I was flushing the entire house. I couldn't believe how many small rocks I flushed out.