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Patrick, General Contractor
Category: Plumbing
Satisfied Customers: 2429
Experience:  30 years commercial construction and 23 years house remodeling projects
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Problem - Hot water coming out of cold faucets. All fixtures

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Problem - Hot water coming out of cold faucets. All fixtures are mixer type. The system has a hot water recirculation pump at the hot water tank. The washing machine has hot water in the cold cycle. All of the mixer valves now squeak when they are operated. If the cold water side of the valve is left open long enough it will run cold again. This may be related or offer a clue - after installing a higher flow rate shower head in one of the baths the pipes feeding the bathroom "hammer with a half second period of repetition."
I am going to fix this myself but I need a trouble shooting approach and a repair solution that will bring back the system with no air in the lines.
I would tend to lean towards the thought that you have a crossfeed problem at the clothes washing machine. Try turning both the hot and cold supply valve to the washing machine and see if there is any change elsewhere. Allow the water to run in order to flush the hot from the cold line. If this takes care of it you need to have the mixing valves on the washing machine changed out on the machine itself. If it does not take care of it you need to try isolating off each fixture one at a time and see if you are getting crossfeeding through it. Again, you shut off the cold and hot valve under the fixture. Good luck. If this has proved helpful, please remember to hit ACCEPT, otherwise I do not receive credit. Thank you.
Customer: replied 7 years ago.
So this is the gist of it:
1. Isolate the washing machine by taking it out of the loop. If not cause go to 2
2 . Isolate the fixtures one at a time .

The purpose of clearing out the hot form the cold line is to see if the hot water propagates through the cold side of the remaining "online" fixtures - correct? In this manner we can deteremine that the valve taken offline is "crossfeeding" ?

If I work my way though all of them then that would leave the recirculation pump - right ?

Is there and easy way to take that out of the loop ? Does the pump motor always run ? Could I check that it is running using my stethoscope ?

If I need to replace the recirc pump i would:
1. Shut off all water
2. drain the hot water tank ?
3. cut out the pump - hacksaw
4. replace pump with new and reconnect using the new copper pipe - no solder connection - it isn't soldered in anyway.
5. Turn on the water and check for leaks
6. Is the air in the system vented out at the faucets ?

Why is the water pipe hammering with increased flow ? Is there a way to fix it without going back to a low flow rate shower head.
Right on line. The circulation pump should do nothing more than take water from the end of your hot water piping and run it back to the beginning to keep the water in the pipe hot. You may be able to just turn it off, otherwise the motor always runs, unless it is on a timer. If you are lucky you may have isolation valves on each side of the pump to be able to remove it without having to drain everything down. I suggest you purchase a tubing cutter to cut the copper pipe, inexpensive and much neater. Any air in the system can be flushed from faucets. You may want to check the pipes for the shower and make sure they are secure. Good luck. if this proved helpful, please remember to hit ACCEPT, otherwise I do not receive credit. Thank you.

Edited by Patrick on 1/21/2010 at 5:07 PM EST
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