Low water flow to a shower head can be caused by a low-flow rough-in valve/cartridge

[Cory Hank]

Low water flow to a shower head can be caused by a low-flow rough-in valve/cartridge

Every hotel I've ever been to has a shower head that blasts me with more water than I could ever need. But the one in my house sends out just a trickle by comparison. I know there is a federal regulation that requires shower heads to produce no more than 2.5 Gallons Per Minute (GPM) at 80 PSI but I assume hotels are also bound by those rules. I've been baffled by this problem and for years I didn't know how to fix it. Now I've finally figured it out.

I measured the water flow rate from my shower head and got 1.0 GPM, but I can get nearly 10 GPM from the utility sink in my basement. Even when the shower head and tub spout are removed the water flow is 1.4 GPM or less from the bare pipe, so I know it's not the fault of the restrictor in the shower head. I have 40 PSI municipal water and copper pipes throughout the house. Here are the measurements I took:
Shower head: 1.0 GPM
Bathtub spout: 1.4 GPM
Shower pipe w/o shower head attached: 1.1 GPM
Tub spout pipe w/o spout attached: 1.4 GPM
Toilet in the same bathroom: 3.9 GPM
Utility sink in the basement: 9.9 GPM

Since I have great pressure elsewhere in the house, next I checked if there might be something gummed up in the shower valve blocking the water flow. I unscrewed the hot water handle and removed the cartridge, but it was nice and clean and there didn't seem to be any blockage in the pipe, either. I turned the water supply to flush out any unseen blockage that might be in there and just to see how much water would come out. Lots! But when I put the cartridge back in I got the same poor water flow. I did notice the cartridge lets water in through two tiny little holes and thus makes a great bottleneck. It seems like it is designed to reduce water pressure by about 80-90%. It is essentially a low-flow shower valve and no matter what shower head I use it will provide poor water flow.

I did some googling and called some plumbing supply stores but as far as I can tell no one has ever heard of a low flow shower valve or low flow cartridge. Everyone suggests checking for a partially closed shut-off valve in the line, gunk clogging up the valve, a restrictor in the shower head, corrosion inside galvanized pipes, or low water pressure to the entire house. I don't have any of those problems.

I asked some plumbing supply stores and a plumber, but there doesn't seem to be a different cartridge I could buy that would increase the water flow. This cartridge doesn't have a part number or brand name anywhere on it but it looks like an imitation Moen cartridge. After I tried to drill it out and caused a leak, I replaced it with an Ace hardware part called "Faucet Stem Moen Style 6S-1H/C Hot/Cold stem." It's a replacement for a Moen 1224 stem but it looks like my shower never had a genuine Moen part.

I went to Home Depot to check out rough-in valves there, but there is no information provided about water flow rate. On American Standard's website, however, there are some spec sheets for their rough-in valves that give water flow rates. My solution was to replace the rough-in valve with an American Standard part and now my water flow rate is much improved.

I have heard that the 2.5GPM government regulation caused some manufacturers to overcompensate and produce super-low-flow components that are way below 2.5GPM just to be on the safe side. But as far as I know, that regulation applied to shower heads and kitchen/bathroom faucets, not to the shower valves themselves. It seems that my shower valve was made with stems/cartridges that are also used for bathroom sink faucets, and those are limited to 2.2 GPM at 80PSI by law. It just seems like a bad design to carry those parts over to a shower/tub valve. It used to take half an hour to fill the tub, which is really annoying and benefits no one.

 

[Bob S]

Well Heres what i have..granted they are old i was a licensed journeyman plumber, I let my license expire..i am 71. I don't particulary care what the government thinks on water and shower head use.I have better things to do than wait til i get all rinsed off from a stream of water.no bigger than i can urinate.So any help here is wanted, to get this job done by me. not the bureaucrats..and their Dumb as way of "trying to save the water"all the time..RIDICULOUS LAW.Now that i have that off my chest,Iguess i will have to rebuild these old heads somehow.Twenty five years ago i remember now... i put these up in our bathrooms. So will anybody help me on this/// i would like new ones or modifications for one .pm me however you can.Email etc. thanks ...i hope for looking
bob s

 

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[Reach4]

You could try CLR. Usually you use that for calcium deposits, but the R does stand for rust. Click Inbox.

 

[Bob S]

You could try CLR. Usually you use that for calcium deposits, but the R does stand for rust. Click Inbox.

 

[Bob S]

thank you reach4 i took the "low volume junk" back to the store.I rebuilt my old ones works good now!!

 

[Bob S]

You could try CLR. Usually you use that for calcium deposits, but the R does stand for rust. Click Inbox.

I dunked the head parts in Muratic acid for few minutes. Cleaned the rust all off. I bear greased up the parts. Think they may be good for another///////lets just say. .As long as i live.Thank you all for the help


ps; nobody told me how to modify the Small volume heads has anyone here done this ?/ pm is fine bob s

 

[Reach4]

https://terrylove.com/forums/index.php?threads/high-volume-shower-head.61252/#post-453822

Click Inbox. If no messages, try a different browser or browser settings.

 

[Jadnashua]

If you have hard water, the jets can get clogged up. If you have galvanized piping anywhere in the system, the rust flakes can mess things up, and it can restrict the ID of the pipe, restricting the flow. A really gunked up galvanized line might only have the equivalent of a soda straw for water to flow through, and it being rough, slows things down even more. Some valves have inlet screen filters, and depending on your water supply, those can get clogged up, restricting flow. Some valves come with service shutoff valves, those might not be all the way open. The cartridge itself may have crud caught in it.

IOW, there are lots of things that can restrict the flow. A typical tub/shower valve is usually capable of 5-6gpm through the tub spout, and what gets to the showerhead inlet might be restricted, but not all are, but easily more than the 2.5gpm Federal mandate when things are all working properly. There are some super low volume shower heads out there that may only normally have about 1gpm, but most have more. The quality of the shower head also plays a part in this, just like different hose sprayers do...some generate a higher velocity stream than others - depends on design and execution.

 

[Bob S]

If you have hard water, the jets can get clogged up. If you have galvanized piping anywhere in the system, the rust flakes can mess things up, and it can restrict the ID of the pipe, restricting the flow. A really gunked up galvanized line might only have the equivalent of a soda straw for water to flow through, and it being rough, slows things down even more. Some valves have inlet screen filters, and depending on your water supply, those can get clogged up, restricting flow. Some valves come with service shutoff valves, those might not be all the way open. The cartridge itself may have crud caught in it.

IOW, there are lots of things that can restrict the flow. A typical tub/shower valve is usually capable of 5-6gpm through the tub spout, and what gets to the showerhead inlet might be restricted, but not all are, but easily more than the 2.5gpm Federal mandate when things are all working properly. There are some super low volume shower heads out there that may only normally have about 1gpm, but most have more. The quality of the shower head also plays a part in this, just like different hose sprayers do...some generate a higher velocity stream than others - depends on design and execution.

All copper plumbing all mixing valves in good condition.Good pressure everywhere, but that cheap shower head. And its small dia opening- up to 1/2" supply how much you have to pay for a SHOWER head.?Some of this reply sounds like a Dr talking to me.. This is just WATER.

 

[Jadnashua]

With nominal water pressure, you can look at the specs on the valve you have, but most should supply 5-6gpm out the tub spout. IF that doesn't happen, something else is wrong somewhere. You might get a little less than that out of a typical one up to the shower arm, but it is the head that then restricts things, not the valve. A cartridge can look good, but still have issues internally, and, as I said, some valves come with inlet filter screens, and those could be clogged, restricting flow along with any one or more of the issues I listed..

 

[Bob S]

Taking all the water mixing valves in this house won't happen til one quits working. They all have good -solid fast flow at the delivery snouts, all over our house. bob s

 

[Jadnashua]

Except for maybe in California and other states with a severe drought condition, you do not have to replace a valve to comply with the newest rules, you are grandfathered. But, if you are remodeling, depending on where you live, it may be illegal to install one not meeting the current requirements...it is illegal for companies to make new ones that do not meet the current codes.

 

[Bob S]

Good point! my friend "grandfathered in"Would be the exception here.Inspectors where i am are nearly non-exsistant. Country side.I wired my garage 60x32 21 years ago the plumbing and electrical were all in and showing the old inspector peered in the garage before the pour.glanced around.darn near fell over, think he had jus come from the pub loooookkkss gooda meeeee. Ill bbeeee bcckkk for da final. Alls well that ends well. i guess bob s

 

[Jadnashua]

FWIW, if the work that was done did not pass the then current requirements, it can be flagged anytime, and then, you'd probably have to bring it up to current ones. IOW, if it's unsafe, doesn't matter, it would need to be fixed.

 

[Bob S]

Good point! my friend "grandfathered in"Would be the exception here.Inspectors where i am are nearly non-exsistant. Country side.I wired my garage 60x32 21 years ago the plumbing and electrical were all in and showing the old inspector peered in the garage before the pour.glanced around.darn near fell over, think he had jus come from the pub loooookkkss gooda meeeee. Ill bbeeee bcckkk for da final. Alls well that ends well. i guess bob s

23 years ago this all took place