HELP! Water volume/pressure drops during shower. No other water running.

[Pakaderm]

Hello, can you guys help me get this figured out...

Background. I have two pressure regulators to the house, one at the street which splits yard and house, and another in the garage to reduce pressure more.

Street pressure: 160 PSI
My street regulator: previously set to 75 PSI (two years old)
My house regulator: previously set to 55 PSI (at least 5 years old, perhaps more)
Water heater is ~4 years old (50 gal)

Recently, while taking a shower (upstairs, farthest from water supply line), the pressure/volume of water just started to drop. After several seconds the pipes in the wall started to bang/rattle. I shut off the shower. An hour later I tried the shower and the pressure was back to good. I checked the water pressure at the house and it still stated ~58 PSI. I should add this is the first time in 5 years since we've had the house.

I've had this happen to the downstairs shower as well, but not recently.

Any idea what would cause this? I'm worried about the vibration/rattle/banging (of course) as we've previously had the copper develop pinhole leaks.

Thanks,
-Pak

 

[Valveman]

Need to check both regulators and make sure the Thermal expansion tank is still good.

 

[Sponsor]

 

[Martinez838]

Do you have a filter, whole hood filter with a cartridge? May need to be changed

Also, any debris in the shower cartridge? Check that out.

Rarely is it the expansion tank. But if you have one make sure the bladder is at the correct psi.