widespread water hammer/thermal expansion tank


Old 06-24-03, 03:38 AM
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Angry widespread water hammer/thermal expansion tank

we just had a new addition put in with some old pipes cut and after one of these we started to get (what i now know as) water hammer in the cold pipes. it pretty much happens from anywhere in the house.

my theory is that the old pipe - which was not used - created an air cushion and it worked like a water hammer arrestor. when it was taken out, no more air cushion, instant hammer.

there are some loose-ish pipes downstairs but clamping them does not seem to fix the problem.

we had the plumber back and it looks like he installed a thermal expansion tank near the water inlet in the house. it seemed to fix the problem for a day or so, then the banging got bad again.

we are STILL waiting for the plumber to come back yet again, but after having read about water hammer in these pages i wonder whether a) his was the right fix, and b) why it worked for a while and then got bad again.

approaching wit's end...
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Old 06-25-03, 01:38 AM
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You can add clamps to the loose pipes and put wood wedges in the holes where they pass through framing to try to reduce the hammer, or you can add water hammer arresters at each fixture.
What is your water pressure?
The plumber should have a gauge to attach to a spigot to check it. It might help to reduce it a bit.
Good Luck!
Old 06-25-03, 08:01 PM
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The reason it worked for a few days?To install the thermal expansion tank he had to turn off water and drain.This could have put enough air in lines to help for a few days.I would install thermal exspansion tank at water heater.I would install air chambers at farthrest point of system.Does this hammer occur wen useing any fixture or just some? Does it do it while water is running or when water is first shut off.One other thing to check cut off water to all toilets at stops.then turn on water at other fixtures and see if it still does it.
Old 06-25-03, 08:03 PM
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Test the pressure on the house, fast closing valves and high pressure causes water hammer.
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