Shower Pressure Problem

[Jon Tungsten]

Friends,

I have been struggling with the water pressure in our master bathroom for quite some time now. We remodeled the house with all new plumbing and are not able to get adequate pressure.

Here are the details:

1” water supply coming from the street to meter in basement

1” pex water supply line from meter to pex manifold - about 30’ run

1” pex line (hot and cold) from manifold to master shower valve about 25’ run

Shower has one valve that controls 2 shower heads (one wall mount and one ceiling mount rainfall)

Valve- http://www.hansgrohe-usa.com/articl...static-trim-with-volume-control-04352000.html

Shower head 1 - http://www.hansgrohe-usa.com/articledetail-clubmaster-3-jet-showerhead-28496001.html

Shower head 2 - http://www.hansgrohe-usa.com/articledetail-croma-croma-220-air-1-jet-showerhead-26465001.html

We had our contractor run the plumbing and he is not a licensed plumber. The goal was to get great water pressure in the shower so he thought the 1” lines might help. My understanding is that we have good water pressure coming from the street – the sinks have great pressure – though I don’t know what the PSI is. When we run the shower there it is not close to normal water pressure coming out of the shower heads. I had to take out the shower head filter and water volume reducer just to get somewhat decent pressure. Of course, this just dumps the water out and is a huge waste of water. I demoed shower head 1 in a show room and it had tremendous pressure granted it wasn’t going through a mixing valve.

Does anybody have any ideas here? Was it a mistake running the 1” line? Does the valve have any adjustments that can be made? Any suggestions would be greatly appreciated.

Thanks,
Jon T.

 

[Jadnashua]

Are all of the in-line stops on both the manifold and the shower valve fully opened?

That valve is rated at a maximum of 6gpm. With both heads operating, you'd have 5gpm, but if you opened up the restrictor, you would easily be trying to draw more water than the heads were originally designed for, and more than the valve can supply.

Depending on the fittings selected, 1" pex could end up less than 3/4" copper for the ID, but it would still be close.

SOme valves have inlet screen filters, but I do not see any in the parts breakdown, but there could be some crud partially blocking the cartridge. The installation instructions often call for flushing the lines prior to installing the cartridge. That may or may not be an issue, but it could be, and can be significant.

What size pipe did you use from the valve to the shower heads? If the installer used lots of fittings verses clean runs to get the pipe where you want, that can add a bunch of restriction. Another big issue is the bend radius...the bigger the pipe, the larger the minimum bend radius. If you try to bend it smaller, it can end up kinking, and shutting down a significant volume of the pipe's volume capacity.

Usually, the issue is volume, not pressure, since the pressure in the supply will be identical, regardless of the pipe size while static. Friction caused by flow and the actual ID of the piping will lower the operational pressure at the point of use. You only retain the working pressure when the supply is greater than the volume of the outlets. By removing the restrictors, you may be trying to draw more than the valve can supply, and the pressure will drop because of the friction involved and the valve's internal restrictions.

 

[Sponsor]

 

[Cacher_Chick]

I would shut the water off and pull the cartridge out, and then turn the water back on to see what the pressure/volume looks like through the open valve.

 

[Jon Tungsten]

Thank you both so much for your quick responses. Disclaimer, I am definitely new to all things plumbing. It sounds like both of you saying the issue could be relating to either the lines or the cartridge?

Regarding the lines, the inline stop at the manifold is fully open and I believe also at the shower valve. I can open up the wall and double check that when we start to address the issue.

All the runs are direct runs to the controls/fixtures and the pressure is poor when running either one of the shower heads independently. To clarify, the shower pressure is almost non-existent when I have the flow restrictor and filter in the shower head 1. When I remove those 2 pieces, the pressure is improved but below average but just uses extreme amounts of water (75 gal hot water tank will be cold in 15-20 min of shower use)

My understanding is we ran 1" pex from the meter to the manifold then used a 1/2' reducer into the manifold. Then 1/2" reducer out of the manifold and 1" pex to the shower valve using a reducer at the valve. We then ran ½” pex to each of the 2 shower heads. There is no connections in the lines other then the reducers. There is very little bending in the lines as the manifold is located directly below the shower. Does it sound like there could be any issues with the lines?

The pressure was poor from the time we first installed the valve when new- do you think there can still be an issue with the cartridge? I can get the cartridge removed. Any guidance on how to clean the cartridge? How do I know if I have adequate volume and pressure on the lines?

 

[Cacher_Chick]

If there is good flow from the valve body with the cartridge removed, i would install a new cartridge.

 

[Jadnashua]

Unscrew the shower head, turn the valve on, put a bucket underneath and see how much water you get/minute. Anything more than what the shower head uses should not limit the head. Put it back on, then run the test again to compare the output available.

It sounds like you have a 1/2" outlet manifold. While going to a larger pipe from there, that restriction is still just that, a restriction. Water tends to speed up through a restriction, and then slow back down again, so it depends on how long the restriction is as to how much it will drop the dynamic pressure because of that friction, and thus the volume available. The ID of 1/2" pex (and the manifold outlet, too) is barely the same as a 3/8" copper pipe which will not have great volume. Frictional losses will reduce the pressure. It would have been better to have a manifold with a 3/4" or even 1" outlet to maintain maximum flow on that branch.

Finally, the valve you've selected, assuming I read it right, is limited to 6gpm at the indicated supply pressure AND they base that on a copper supply pipe, not pex.

You didn't answer whether they used pex to plumb the shower heads, and if they did, what size.