Is it correct to think that if 4 body shower heads are fed from one 1/2"
line the volume per head will be reduced to one forth of the 1/2 inch
line with the same pressure. The shower heads (kohler k-8506) use 2.6
gallons per minute for a total of 10 gallons per minute. Will one
1/2" line hold enough water at 60 psi to get the maximum performance
from the shower heads?
Thanks for any help
Yes........except.....the shower control (faucet) very likely
has internal restrictions built in which will greatly limit the
total flow. If this is a new install you're considering,
mock up the connections in the backyard (or somewhere) using
the brand/model of shower control in question. Measure flow
into a bucket.
Thanks for the help. The conrol valves are 3/4" being fed by 1" lines
of hot and cold. Great idea about laying it out and testing the flow --
the plumbing is already in the wall in rough out stage which may allow
us to test it.
Speedy Jim wrote:
Go to a site that offers lawn sprinkler design information. It will give
GPM for various pipe sizes and supply pressures. Here's one, but it
doesn't give pipe sizes as small as 1/2", but 5/8" allow 10 GPM, so 1/2"
would be less:
A problem like this obviously can be solved several ways. I think that it
can be done easiest graphically. You take each system ---the supply line
with its respective fittings, the shower head and any other line
restrictions---and plot their flow characteristics separately and then
graphically put them all together to define the whole system.
This will probably sound more complicated and/or confusing than it actually
1.0 Measure and calculate the number of equivalent feet in your supply line.
This includes the length of the pipe plus the number of feet added due to
various fittings. The line will have a pressure drop/100 ft as a function of
the flow going through it. The line/fitting resistances can be found via
various available references (using Goggle is one source to find them) .So
first step is to vary the flow and calculate a delta P for each flow. Plot
Delta P (Y axis) vs Flow (X axis).
2.0 Characteristics of the shower head. Per Kohler--2.6 GPM at 60 psi
(since there has to be a pressure drop associated with the flow and I will
assume it's 60) Use whatever it is anyway. I also will assume that it's
flow characteristic is GPM=f(sq. root of delta P). So what this means is
that GPM=K*sq root Delta P. Solve for K which is = 2.6/sq rt 60. Now for a
bunch of different Delta P's calculate GPM (using the K just calculated).
For four shower heads, multiply the GPM just calculated by 4 for the same
Delta P. As before, plot Delta P vs GPM (4 shower heads) on the same curve
as the supply line.
3.0 Merge the two plots together to get a total system characteristic. You
do this by looking at a GPM and then add the Delta P for the line and the
Delta P for the shower head and plot that resulting Delta P for the same
flow. This will result in a curve that represents the whole system. The
input to the supply line defines the starting upstream pressure and the exit
of the shower head is the downstream pressure (ambient) so for all practical
purposes, the supply pressure is equivalent to the system Delta P.
So now plug in any Delta P in the curve (60 in this case) and look down to
see what the resulting flow will be. The beauty of the plot is that you can
get a system flow for any supply pressure. Obviously, the accuracy of the
resulting flow is dependent on just how well you've describe all the system
resistances--such as the shower valve itself etc. Worst case is to get that
info from the manufacture himself--their customer service or tech support
are usually quite helpful.
I've used this method of getting answers for some systems that otherwise
would be much more difficult to obtain.
You are a wise man.
Who needs four showers at once, anyhow? You running a gym or a spa?
Hint: Use full flow shutoffs. Ball valves or gate valves have a lot less
pressure loss than globe or angle valves.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.