PEX Pressure drop issue

[Scott Morey]

I have a 2nd story bathroom with 1/2" PEX running directly to the shower mixer from the 3/4" supply manifold downstairs (maybe 20 feet away). I installed a bar sink on the opposite side of the wet wall and installed a tee fitting with cinch clamps to tap into the 1/2" PEX lines that are supplying the shower (these branches will supply the sink when it is plumbed and are about 17" long but not in use yet). After I installed the branches in the 1/2" shower supply lines, I noticed a large pressure drop in the water coming out of my shower head. Does anyone know what would cause this? Are the tee fittings restricting flow to the shower? I also notice a loss of hot water after just a few seconds of running the shower. Could it be an obstruction in the line? The branches I installed in the 1/2" shower supply are about 18" below the shower mixer. There are no pressure or hot water issues at any other faucet or shower head in the house. Any insight is appreciated!

 

[WorthFlorida]

Did you flush the lines before connecting the PEX to the valve body? If you replaced the shower valve body the instructions will recommend to flush the lines before installing the cartridge. This may not be your problem but it is where you start.

 

[Sponsor]

 

[Mliu]

How old is the original PEX plumbing to the shower? Although PEX is resistant to scale, it is not immune from scale. It's possible that when you cut the original PEX tubing, some scale flaked off the inside. Then when you ran your shower, that scale migrated to the shower valve, clogging it.

As Worth stated, you should start by removing the shower valve cartridge, cleaning it, and flushing your lines. While you're at it, remove the shower head and clean that too.

 

[Scott Morey]

How old is the original PEX plumbing to the shower? Although PEX is resistant to scale, it is not immune from scale. It's possible that when you cut the original PEX tubing, some scale flaked off the inside. Then when you ran your shower, that scale migrated to the shower valve, clogging it.

As Worth stated, you should start by removing the shower valve cartridge, cleaning it, and flushing your lines. While you're at it, remove the shower head and clean that too.

It is fairly new pex. I believe that the previous owner installed it in 2013. I didn't even think of the cartridge - I'll start there. Thanks!