How to Flush Hot Water lines

I have recently moved into a brand new home. The hot water lines seemed to be getting less and less pressure every time they were used. Many of the aerators were clogged with a green color debris. We have copper pipes.
The contractor brought the plumbers back and they supposedly cleaned every fixture and flushed the lines for an extended period of time.
The Shower has a Moen mixing temperature mixing valve which apparently has filter screens before the cartridge which can not be easily accessed (at least not by me).
Less then two weeks after flushing the system, the mixing valve is not letting any hot water through the shower head again. We get plenty of pressure if I set the mixing valve to cold and almost none to the hot side. I assume this is a indication of the problems being only on the hot water side. I also assume the cause is that the screens are clogged again.
My question is, what is the best way to flush the copper piping? What could possible be causing this much garbage in the lines? Is this common in new construction?
Thanks for any help.
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Some debris is inevitable in new plumbing but you seem to have an excessive amount. It sounds like the builder was careless and left the rough plumbing open while the other trades worked. A more professional approach is to cap the open ends of pipes that are yet to be connected to valves, faucets, toilets, etc. But it takes a little time and "time is money"...plus you have to care about the quality of your product.
The green debris is probably a byproduct of corrosion since many copper salts are green. Flushing the lines is the most practical approach but you'd best plan on cleaning all filter screens after a month or so.
Make sure that there are filters in the lines to your clothes washer, dish washer, ice maker, etc. because this debris could get trapped in one of the appliance's fill valves and result in a mini flood if the valve can't close completely. I've had it happen.
RB
Bruce wrote:

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RB:
Thanks, I believe you are correct about the lines possibly being left open. After several flushings, can I expect the problem to clear up or is it going to be persistent for a while? Why only the hot water lines?
Bruce

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Did they flush the water heater?
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They claim they did.
We have also started noticing a very fine black colored (almost soot like) material clogging some of the screens now. Any idea what that could be?
We are going to check with some of the neighbors who recently built homes to see if they are having problems.

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The green color sounds like its from your house, I put in a cheap whole house filter the one with a clear casing from HD so you can see filter condition. Ive never had poblems but after a week of running the filter it was brown and specked with white like PVC shavings . I know the water co people, they said there is always work going on , but its normal work. I know ive kept the crap out of my system from cloging apliances. Just an inexpensive idea that may help for the future.
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Could be that the debris is only in the hot water lines and/or tank.. Could also be that the hot water is better able to dislodge debris than cold water. It'll clear out in time but it is a nuisance and could have been avoided.
RB
Bruce wrote:

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It could be and probably is the main supply, I assume its city water. A mains filter is always a good idea and inexpensive.
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Ransley:
Thanks for the reply. The water is city water. I previously lived on the same block and have had no problems in the old house. The problem still exists only on the hot water side.
Do you still think it would be the city water?
Bruce
On Wed, 28 Jan 2004 12:28:52 -0600 (CST), snipped-for-privacy@webtv.net (m Ransley) wrote:

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If the builder thought it might have been the city water, I am sure he would have tried to blame them for it.
--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math
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