Moen Positemp Shower Valve Issue

kameda

Recently replaced a faulty PRV valve and set the pressure to the house at 70 psi. Before the change my master shower had lower operating flow than the same valve in my main house shower. The master shower flow did improve but now I am noticing what I can best describe as intermittent trapped air coming through the valve. When I hear this I can also see a slight pulsation of the water coming out of the shower head. My wife's complaint is that the flow rate is not the same as it was when we initially moved in. We are the original owners having moved in in late 2019. Any ideas for diagnosing and fixing this issue are appreciated. Happy wife means Happy husband.

hot_rod

If work was done on the piping, you could have flushed debris into the shower head?

Remove it and soak in vinegar to clean dirt and calcium scale. As a first step.

Or debris into the Moen cartridge, simple enough to swap that out. Depending on the model, I believe that is a pressure balance valve and cartridge.

70 psi is fairly high, PRVs ship pre-set a 45- 50 psi typically.

Do you have a thermal expansion tank at the water heater. Many of the PRVs act as check valves also, the non bypass models.

kameda

Yes I do have a thermal expansion tank on the hot water tank. As for the valve cartridge, it is a 1222 model. I am almost positive there is no debris in the shower head. No way to know about the cartridge without removing it.

Alan (California Radiant) Forbes

I would replace the cartridge and while the cartridge is removed, turn on the water to flush out any debris in the hot and cold lines.

Have someone at the house valve turn on the water for 5-10 seconds and a second person at the valve with a 5-gallon bucket and see if you get any debris at the bottom of the bucket.

Add some good quality silicone grease to the o-rings on the cartridge and also inside the valve before you push it in. Moen used to include a little packet of lubricant with their replacement cartridges.