6 Aug 2000 at 11:35 pm #273322MasterPlumbersKeymaster
What would make the plumbing in a house (copper piping) start leaking inmany different areas
with no obvious problems detected with the electrical system.
7 Aug 2000 at 12:12 am #287367
High water velocity may be caused by an
undersized piping system or excessive pressure. . The
real solution is to lower the water velocity. The relationship is as
follows: Reduce pipe size, increase velocity; increase pipe size, reduce
velocity. Recommended velocity for hot water in a copper tube system is 4 –
5 feet per second (fps). If systems are designed to respect these velocities
the return lines will last as long as the rest of the system. The practice
of reducing tube diameter for the return line run is counter-productive and
is the main cause of high velocity in these systems. Since there is no
sizing guide in the Model Codes for return lines, there is little guidance
for the plumber on how to size this portion of the system. In the course of
installing or replacing circulating lines, some contractors have been
increasing the size of the return loop piping to 1″ or at least the same
diameter as the hot water supply out of the water heater.
Numerous, abrupt changes in direction in the piping system. Where
structural conditions cause numerous directional changes, long radius (1.5
Diameter) fittings should be used to minimize the interruption of laminar
In other words you need either a pressure reducing valve OR increase the diameter of the piping. You should also have the water tested for PH content
Another factor affecting copper tubing is if the instlaller didnt ream the tubing ends prior to soldering this would turbulent flow and erosion as lack of reaming the tube ends. Burrs left on the ID of the tube can
cause interruption of laminar flow resulting in localized high water
velocity and cavitation.
Protrusions into the flow stream caused by excessive lumps of
solder/brazing material, improperly fabricated tees (branch protruding into
the run pipe), etc. These protrusions can also cause the
interruption of laminar flow resulting in localized high water velocity and
A lot of misfits also use self cleaning (ACID) fluxes and never properly flush the system (joints) and over time this flux actually eats away at the base metal.
Excessive water temperature. Heating water above 140 degrees Fahrenheit
can accelerate the process of erosion/corrosion. As the temperature
increases, the velocity should be lowered. At 180 degrees Fahrenheit, the
velocity should be down around 2 – 3 feet per second (fps).
Bear in mind that these conditions are not peculiar to copper tube, but can
affect other materials as well. However, when erosion/corrosion does occur
in copper tube it is readily identifiable by the horseshoe shaped pitting
throughout the inside of the tubes. Identification OD these pits or grooved
corrosion-product-free areas on the inside of the tube can help you
determine that water velocity is too high and that the reduction of velocity
can correct the condition. Good luck
18 Sep 2000 at 8:35 am #287368
Please post more details for discussion. We have a neighborhood that has 60+ homes that have 1 to 14 leaks occur in last 6 months. For 3 possible causes, see posting by SteveG. on 9/16/00 titled Pin hole leaks in copper.
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