What causes a shower to "pulsate" only at certain tempuratures? Mine only happens in the middle of the dial. I can make it stop by turning the tempurature hotter ( too hot for my liking) or colder (also not my preferred setting). It doesn't do this all the time and usually doesn't start until a few minutes into my shower. It only happens in one of the showers in my house. It's a Moen system and I have already replaced the valve with no change.

Is it a single handle or two handle faucet ? Is it pressure and / or temperature balanced valve ? Are you on pump ?

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Milo

Is it a single handle or two handle faucet ? Is it pressure and / or temperature balanced valve ? Are you on pump ?

Back to you

Milo
It is a single handle Moen shower valve. I believe it is temperature balanced as the pressure is normally consistent. To my knowledge we are not on a pump. This is the only shower in my home that does this.
I said we replaced the valve but really only changed the valve cartridge. That had no effect.

When you say "...you have replaced the valve...", you mean entire valve or just a cartridge ?

Milo

Just the cartridge.

There are two things regulating water flowing through the cartridge. One regulates temperature and the other regulates flow. It sure sounds like the cartridge is bad.

Does this happen when no other plumbing fixture in the house is in use, including sprinklers or any other water using device in your house ? Also, do you have hot water circulating pump ?

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Milo

There are two things regulating water flowing through the cartridge. One regulates temperature and the other regulates flow. It sure sounds like the cartridge is bad.

Does this happen when no other plumbing fixture in the house is in use, including sprinklers or any other water using device in your house ? Also, do you have hot water circulating pump ?

Back to you

Milo
This happens when the only device using water is the shower. To my knowledge there is not a hot water circulating pump.

What seems odd is that it only happens at certain temps. If I adjust the knob to make it hotter (past a certain point) it stops happening. Same thing if I make it colder (too cold to enjoy the shower).

That indicates the cartridge balancing mechanism is not working properly. There is a piston-like device that moves sideways with changes in pressure or temperature. I would definitely change the cartridge.

Moen has one of the best warranties. Call Moen, explain them what is going on and they will send you new replacement parts free of charge.

Call Moen U.S. 1-800-Buy-Moen (1-800-289-6636)

8:00 am to 7:00 pm EST Monday through Friday
9:00 am to 3:00 pm EST Saturday
Closed on Sundays and all nationally observed holidays.

Let me know what they had to say

Milo