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Poor shower volume/pressure in all but the master bath

269 Views 6 Replies 2 Participants Last post by  jmon

I apologize if this is well covered territory, however, my exhausted search on the internet has not yielded any actual solutions that have worked. Maybe my Google-Fu is not black belt worthy...

Additional disclaimer: I am a decent DIYer, though perhaps not in tune with all of the terms related to plumbing.

I have a relatively new house (3 years old); good water pressure entering from city water at the street, tankless water heater, and good pressure at exterior spigots, all faucets, the washer and dishwasher. The house has four showers (one on the first floor, three on the second floor); the only one with really decent water pressure is the master bathroom (second floor), which has two shower heads. Even when both of those shower heads are on, there is pretty good pressure.
The other three showers, however, have poor water pressure. We never really used the other showers because our kids are really little and have always taken baths or have been showering in the Master bath. Well, now we are moving them to their bathrooms and its a bit undoable with the poor pressure.
All of the fixtures are Mirabelle (Key West), single handle. I took one of them apart to see if it was the hot/cold mixture (mixture was good), or if it were the control valve that has set screws on both the hot side and the cold side that you can tighten for less pressure, and loosen for more pressure. It had about half a turn left to be full open, which I turned it to, yet the volume was essentially unchanged.

Someone told me that the pipes may be different in the Master bathroom? but that doesn't really make sense to me, as the pressure should still be the same when it comes out of the shower head...

Im really stuck - any advice would be greatly appreciated!
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sometimes sediment gets stuck/builds up in cartdrige. first try removing shower heads and cleaned them up or just replace them. Remove shower head and turn on water, if good pressure replace/clean shower head.

Also check to see if there is a water restrictor washer in shower head. Remove it, if there is. If house is only 3 years old i'm pretty sure you have them.

if none of that works, remove and clean the cartdrige as it may have sediment built up in it.
Thanks so much for the reply! I took apart the shower heads and, as I kinda figured, as clean as a whistle. I tried running the shower without the restrictor in the shower head, but there was absolutely no change.
That being the case, and all of the barely used showers being squeaky clean, I don’t think the cartridge is clogged either - though I didn’t take it out. The tool I have to remove the cartridge (from a different shower fixture I repaired, different house) has a screw that doesn’t fit the Mirabelle unit I have now, so I’m not sure how to take out the cartridge.
It doesn’t get super hot, maybe the problem is not allowing enough hot water flow to make a larger volume?
I’ll try to attach a picture...


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I know you said you removed the restrictor and no change in water pressure. How is the water pressure without the shower head installed ??
yes, I agree with you, house is only 3 years old, i doubt you have any sediment buildup either.

If shower is not getting hot enough, that can easily be adjusted. Google mirabella and pull up the directions on how to change it. They are all a little different. Best to get the right instructions from the right manufacture on how to do it.

I'm sure there are some utube videos out there showing how to do this as well.
Thanks again - wow, you're fast!

I took off the restrictor and the volume was the same... As was the volume with and without the showerhead. I checked that when I cleaned/inspected the screen. Though, i could not remove, or adjust the green tinted pice that restricts the movement of the handle when the restrictor piece is installed.

Ill try removing the cartridge.

I was wondering though, if the flow control unit all together that is behind the wall is perhaps not the correct size for the shower?
I was wondering though, if the flow control unit all together that is behind the wall is perhaps not the correct size for the shower?

It looks correct. You said you verified that the supply stops were open all the way, correct? (The flat head looking screw type stop on the valve housing) ccw opens cw closes.

Agree, remove cartdrige clean and reassemble. Make sure you remember how it goes in. Take a picture.
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