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Loss of Water Pressure - 90 Deg Angles?

Posted by renos (My Page) on
Mon, Aug 30, 10 at 12:11

Would anyone happen to have some insight into angles in copper piping and the imapct on water pressure? I am renovating my bathroom and in order to accommodate a 'niche' on the shower head wall (in between the head and the control fixture) the plumber routed the piping around the niche area. Meaning instead of a pipe straight up to the shower head he used a three(?) 90 deg angles.
No my building reversed their original approval and says I can't build the niche!

Would any one know if these angles will significantly affect the water pressure from the shower head? Should I consider removing that part of the tile and having a new pipe put in that goes straight up to the head? Thanks a million for any advice!

Follow-Up Postings:

RE: Loss of Water Pressure - 90 Deg Angles?

You don't mention pipe type, pressure, distance, fitting type so I'll answer in generality.

1/2" copper has a head loss of about 12' for 100' pipe at 3 GPM, which equals 5.19 PSI drop per 100'. 1 - 1/2" copper 90 = 1.5' of pipe in head loss.

Short answer an extra 90 will cause about a 0.65 PSI drop, an extra foot of pipe will equal 0.27 PSI drop at a standard shower head, I doubt you will notice that.

RE: Loss of Water Pressure - 90 Deg Angles?

Basically, it's no, as zl700 said already, unless (based on other factors that you would already feel at other water sources in your home) you are already certain that you are at the limit ; i.e. your water pressure, pipe size, pipe length, etc.

Based on your wording above, it seems that there is no membrane between the wall tiles and the studs. This is serious. You are renovating but creating a disaster.

RE: Loss of Water Pressure - 90 Deg Angles?

Thanks for both so much your comments. I'll try to get more information. This does involve 3 elbows instead of the straight line in the regular small copper piping (Hansgrohe fixture). I'm concerned though when you say I am 'renovating but creating a disaster'! Not sure what you mean by a membrane between the wall tiles and the studs. There is the 'wonder board I think? and then a big air space back to the back wall of the conpacter area (thus I thought I could build a niche there but the condo retracted their original yes to a no). Sorry but not being very technical in these areas I do try to do my due deligence but suspect I am somewhat at the mercy of the workers! Many thanks for your help!

RE: Loss of Water Pressure - 90 Deg Angles?

If the niche is out why not straighten out the pipes?

RE: Loss of Water Pressure - 90 Deg Angles?

Actually the wall behind the tub is closed and tiled so hard to get to it. However I may be replacing some tile in a strip about 12" to the left of the shower faucet so maybe the plumber can work through that. Will have to see. Thank you.

RE: Loss of Water Pressure - 90 Deg Angles?

Pressure loss due to elbows is not the only issue you are potentially dealing with here. On their own, the additional elbows in the pipe will not cause any noticable pressure loss. However, when water flows through an elbow, the flow pattern is disrupted significantly and needs distance to smooth out again so as not to cause problem in your shower valve. For this reason, shower valves will specify the minimum length of straight pipe necessary before entering the valve. You need to look at the specs for your shower valve to ensure the last elbow is far enough from the valve. Otherwise you will have a problem with sporatic flow, the showerhead spitting water at you in spurts, inability to control temperature, all generally unpleasant, not to mention potentially damaging to your valve.

As to the membrane davidro1 referred to: Waterproofing. You must have some waterproofing mechanism in a shower installation or it will leak into your walls. Wonderboard IS NOT waterproof.

RE: Loss of Water Pressure - 90 Deg Angles?

Op said the pipe was the riser to the head.

RE: Loss of Water Pressure - 90 Deg Angles?

Ah, yes, I missed that somehow. Oops

RE: Loss of Water Pressure - 90 Deg Angles?

hey renos, you better go web searching.

"shower membrane"

and learn fast.

You have no waterproofing in your shower walls.

There could be more bad news.

Open a new thread about this when you have read a little.


RE: Loss of Water Pressure - 90 Deg Angles?

davidro1 - That is not necessarily true. OP may have seen waterproofing and just not known what s/he was seeing.

RE: Loss of Water Pressure - 90 Deg Angles?

Thank you all for your input. I know they used the wonder board on the walls and Laticrite on the floor and 6" up the walls outside of the tub. I don't recall any others special membrane in the tub area but I will check with the contractor. Also noted your comments about making sure the elbows work with the valve etc. so I will check this with the plumber too. Thanks again!

RE: Loss of Water Pressure - 90 Deg Angles?

You need to know a lot more about "missing membrane" right now.

Start a new thread immediately, with the appropriate subject line.
Post whatever the contractor tells you he did.

This thread is an old one, about a non-problem: elbows in the riser pipe.
((renos, it seems you didn't catch that it's not a problem.
the posts made on
Tue, Aug 31, 10 at 19:19 and
Tue, Aug 31, 10 at 22:16
annulled the statement about the possible problem.))

A new thread will get eyeballs, from people who know membranes.
Laticrete only six inches up, is so-so construction.

Laticrete videos are on youtube.

Laticrete has a web site where you can read more.

HTH !!

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