Low flow rate from shower head

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JoeyDYI80

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My master bathroom shower head has very low flow rate. I've change several heads and still the flow is low. I took off the shower handle and the back plate to see if I could adjust the hot and cold water that is coming into the handle. However, there seems to be no set screw that controls the hot or cold water on either side. I've seen videos online where there should be screws on either side to control temp/flow rate for the cold and hot water coming into the shower and you can adjust it using a screwdriver. But, it seems mine is not setup like that. So what are my options to increase flow rate? Should change the cartridge then to see if that helps? By the way home was built in 2005.

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Reach4

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Characterize low. If you take off the showerhead, how long does it take for water from the open arm to fill up a 5 gallon Homer bucket?
 

JoeyDYI80

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Characterize low. If you take off the showerhead, how long does it take for water from the open arm to fill up a 5 gallon Homer bucket?

I just a did test and the master shower takes about 5.5 minutes to fill a 5 gallon container while the other shower that is in the middle of our upstairs takes about 4 minutes to fill a 5 gallon container. I did not test the 3rd shower that is downstairs. The master shower is the furthest from where the boiler (located in the garage). What do you think of the numbers? I think both are rather low numbers since I think those should be around 2 - 2.5 GPM versus what I have around 1 GPM.
 
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Reach4

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Yes, 5.5 minutes is 0.91 gpm. That is with no showerhead?

If you put the temperature to full cold, does that increase the flow?

For under $20 you can get a garden hose thread pressure gauge. You could put that on a laundry tap or the drain for the WH. Is it just showers, or maybe more. So read the pressure while not using water, and also while running a shower. The purpose of the pressure gauge check is to make sure the pressure is not low for the whole system. The pressure will be lower due to higher altitude. So if the pressure downstairs was 25 and upstairs was 20, that would make the flow lower upstairs. I am not saying that is what I expect, but more information for those who actually know your shower valve could be useful.
 
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JoeyDYI80

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Yes, 5.5 minutes is 0.91 gpm. That is with no showerhead?

If you put the temperature to full cold, does that increase the flow?

For under $20 you can get a garden hose thread pressure gauge. You could put that on a laundry tap or the drain for the WH. Is it just showers, or maybe more. So read the pressure while not using water, and also while running a shower. The purpose of the pressure gauge check is to make sure the pressure is not low for the whole system. The pressure will be lower due to higher altitude. So if the pressure downstairs was 25 and upstairs was 20, that would make the flow lower upstairs. I am not saying that is what I expect, but more information for those who actually know your shower valve could be useful.
Downstairs shower without any shower head is running at 2 GPM. So double than what I get upstairs.
 

jadnashua

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California has instituted code calling for less than the national limit on a showerhead which is 2.5gpm. Given the west's water situation, that's probably a good idea.

Volume depends on both the available pressure, the height it has to rise, and how much friction there is in the piping based on the distance it has to travel and how convoluted that path is. There's dynamic pressure while flowing, and static pressure while it's not. The larger the pipe size and fewer turns it has to make, the less dynamic pressure loss there will be.

If you take the shower head from the first floor, and put it upstairs for a test, what volume do you get? Say the difference in height is maybe 8', that's only a static pressure drop of 8*0.43# or 3.44# less...probably not enough for you to notice.

Some shower valves have internal screen filters in them, and yours may be clogged. Or, the cartridge may need to be replaced, or there could be some other obstruction along the way.

FWIW, in-line valves before the shower valve are not a standard thing, and are not intended as a throttle...they're there for maintenance so you can shut the water off to ONLY that valve, and not the whole house if you need to do something to that valve. They should be fully open or closed.
 
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