I'm a home owner who was fortunate enough to contract for a major renovation of the back part of our 100 year old home in Chicago in late 2006. The project was specified by an architect and performed through a single general contractor. It involved adding new copper piping to a renovated kitchen (2 sinks and dishwasher) feeding from an existing HWH in the basement and adding a new HWH in the third floor attic, to service a new master bath with two sinks, a shower, tub and toilet on the second floor.

Four and one half years after the completion of the project - May 2011, the recirculating pump for the upstairs system failed (high whine) the technician who fixed it indicated that the original B&G unit was installed improperly (shaft was vertical vs horizontal or visa versa) and that the HWH was corroding. The HWH was a 75 gal American Water Heater unit, which was subsequently replaced under warranty.

On December 23, 2011, water started dripping in the kitchen and it was determined to be a pinhole leak in an elbow on a recirculating line adjacent to the tub in the upstairs bathroom. In April 2012, another leak developed, again believed to be in a recirculating line.

At this time, the contractor and his plumber realized that the original and replacement HWH both had aluminum anodes. These were replaced as given Chicago water, magnesium anodes are typically installed in this market. At this time they also verified that the system was and had been properly grounded. The improper anodes were identified as a potential issue, as the same HWH was installed in another renovation started about the same time, 2006, and this resulted in leaks and slime, within one year of completion. No water quality issues have ever been identified as part of the system.

Next in December 2012, another leak developed in a recirculating line, and then finally in early February two more leaks developed in recirculating lines, one adjacent to the HWH and a second in an elbow above the kitchen, but servicing the up stairs bath.

At this point, as the home owner we have called the contractor and his plumber(s) and the architect back to try and figure what happened. Given that the issues are isolated to the upstairs system, which has a separate HWH and a pump as part of its recirculating system, the causes for the problem have been attributed to:

* substandard imported fittings which may have slipped into the supply chain during the 2006 building boom - note same fittings would have been used in downstairs system also. Improper flux, some of the leaks are near the joints between the pipe and connectors, but it is likely that the same flux was used upstairs and downstairs.
* existence of recirculating pump, which operates 24/7, and put undue stress on the short upstairs system - although a pump was specified for the downstairs system, one was not installed as contractor/plumber decided it was not necessary.
* damage to the pipes caused by the 4 1/2 years of operating with aluminum anodes in the HWH.

Suggested courses of action are:

* Elimination of the recirculation system, capping the pipes at the HWH and where it ties into the hot water line near the farthest outlet - tub.
* Install a lower volume pump, which operates only in the morning to facilitate a morning shower, to place less continuous stress on the system, while maintaining the convenience of the recirculating system.

These solutions imply that the issue is restricted to the recirculating lines and that the primary hot and cold water lines are not defective or damaged possibly by the aluminum anodes in the HWH - not sure if this is even a plausible possibility.


This group seems like they could have some input into what might be happening, so I am hoping to employ what I believe is called crowd sourcing to help me decide what my next steps should be.

Thank you.

If I was to pick one, I'd say the pump was oversized, or under restricted.

Suggested course of action?
No disrespect to Archies and Engineers
Know whats worse?

Two of them
And usually they come in pairs

I think, you may have aggressive, low pH/soft water

Water analisys may be required. Please post back with the results

hj is from Chicago, he may povide some insight on local water chemistry

Good luck

For your personal satisfaction you can verify water PH with the cheapest / simplest pool water test kit (aprox $10) available. Of course any pool supply store will test your water PH for free. Water PH of 7.2 is "neutral". Below that is toward "Acid". Far below could cause problems. Testing PH may/may not rule out potential problems

Leaks in the recirculation line, expecially in a "short" system, are almost ALWAYS caused by excessive velocity in thelines. The solution is to install a valve between the pump and the water heater, absolutely NOT ahead of the pump, and then throttle it down until the pump just maintains the water temperature.

velocity of flow in Cu must be limited to 6 feet per second MAXIMUM

recommended vel. for a 'recirc' = .5 to 1 ft/sec

assuming (i know, i know) your job was built as per the specs ~ let the architect and engineer absorb the resulting costs of the improper design

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



Edited 1 times.

You may wish to contact:

The Plumbing Council of Chicagoland
800-768-2853 (76-VALVE)

With any concerns regarding licensed plumbers and plumbing contractors.


Best Wishes

It is NOT a result of "bad design". It is a problem with the pump's output not being regulated.

Love copper.learn what your mechanic did not///burn\\\?What can over heat of fixed joints cause?SORRY.You have the tubing and the joints?look at the tubing?is it flaking or building green bulbs inside it.are all the leaks with in an inch of heat points?If you can see what you have it can be fixed.24 /7 circ even with temp control is waste full.time to use periods at minimum.Leave b and g pumps and go Grundfos. all in one and done.



Edited 1 times.

My friend
It is bad design
Some 'professional' or pump "expert' picked the pump
You know what those folks do...................................I hate to be wrong, so I will oversize it
Uh huh............Just put in the BIGGEST thing you have in your catalouge
Wow!
That was a close one!
;-P
Be kind ALWAYS
Dale

Give me the make and model of the pump, size and length of the recirc loop, and I'll give you the approximate velocity of the water.

Even an "undersized" pump can create excessive velocity. The "proper" velocity can only be determined by testing the system under "active" circumstances.

quote; length of the recirc loop,

Including EVERY elbow and change of direction. You CANNOT determine the "proper" velocity because all that is necessary is that the return line stay warm, and that is also a function of the pipe's "environment" and insulation.

[www.taco-hvac.com]
+ perfection +

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I'd use Taco's method for determining head.It accounts for fittings in the loop. Then look at the pump curve for whatever circ they are using and determine the flow. Then I'd use B&G's System Syzer program to determine velocity. It will tell you if there is excessive velocity.

I agree with Plumbum....You don't guess at anything.The tools are available to anyone. Certainly a Journeyman plumber should use them.

Thanks to all. I am posting some pictures of the first leak, along with the corroded elbows.

[docs.google.com]
[docs.google.com]
[docs.google.com]


Recall that the pump was replaced after 4.5 years, by a different plumber than did the original installation. It is not clear if the original installation had a regulator valve, but the current installation does not - a "one way valve" I do not believe is a regulator valve.

The scary thing to me is that the idea of a regulator valve has not come up with any of the plumbers who have come in to look at it - I talked to B&G asking how the flow is regulated (the model is NBF-22 103252LF) and he deadpanned "with a valve".

I'll pursue that path. Thanks again for your participation.

your pump will 'push' 15 gpm into a 5' head ~ 15 gpm @ 2.155 psi 'friction head'

way way way oversized for a domestic hw recirc

you will need a balancing/regulator/circuit setter type valve installed @ pump discharge



ps. the first pic shows erosion damage ~ PROBABLY caused by excessive velocity

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

quote; The scary thing to me is that the idea of a regulator valve has not come up with any of the plumbers who have come in to look at it

Most don't know about it. To them, a valve is either open to let water through or closed to stop it. They do not consider it being partially open to control the flow, but it HAS to be after the pump, otherwise you will destroy the pump with cavitation.

Overkill for his needs.

Elbows create turbulence at higher velocities and that is what causes leaks at turns.

[unitedstates.xylemappliedwater.com]

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I was looking at the wrong curve.....15 gpm it is.Half inch for the re-circ would be over 20 ft/sec. I wonder how they muffled the sound of the freight train? That circulator is 92 watts. You could save a lot of money by replacing it.



Edited 3 times.

I see deposits on the water-side of your fittings

In my experience, if it is an agressive water problem, the copper will be shiny

If its velocity/cavitation/pumping etc problem you will see oval "scoops" in the metal.

Much like taking an ice cream laddle and carving out a yummy treat out of the container

Good luck

Just want to say I learned a lot in this thread.

Hi,

We are having the same problem and are wondering how you resolved your problem. Any suggestions would be greatly appreciated!