Noisy New Gas Water Heater


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Old 07-26-13, 01:07 PM
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Noisy New Gas Water Heater

We installed a new AO Smith gas water heater just a few weeks ago with a thermal expansion tank as thermal expansion kept blowing out our pressure regulator to the house. Every time after hot water is used, the heater knocks fairly loudly perhaps 20 or 30 times. Asked the installer who called the company and they had no idea. Said if the heater were in the garage we would never have heard it. Any ideas on what might be going on? How about a fix? Hate to think we have to live with this for upteen years. Thanks in advance.
 
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Old 07-27-13, 06:25 PM
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Does your water come from a well? Something is missing. That was a dumb answer about the garage.
 
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Old 07-27-13, 07:01 PM
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Pressure is set to high, the expansion tank is low on air or there's still air in the lines.
 
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Old 07-27-13, 07:14 PM
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to be more clear on what was said here already...


1. The air charge in the exp tank needs to be set at the incoming pressure of the home...
2. If you have a PRV valve at the main coming in the home it may be faulty...
3. You will need to check the psi of the homes water pressure... Get a gauge that attached to a hose bib.. sold at most home stores..
4. PSI should not be higher then 80 psi per code....

Then post back that result and we can guide you further,,,,
 
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Old 07-28-13, 09:15 AM
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Thanks for replying. To answer the question about the well, no we are on city water from the L.A. Dept of Water and Power. The plumber checking out the problem did check pressure at both the tank and the regulator on the incoming line to the house and they were 80--they weren't high. And I know, the stupid answer from the company was ridiculous. I'll work on checking these things out and get back to you...again, thanks.
 
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Old 07-28-13, 01:21 PM
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Here's a bit of information: Checked the exp tank and the label says its "precharged pressure" is 40 psi; haven't double checked psi of the house pressure yet, but I know it was set to 70-80 psi. (And when that was last checked a few weeks ago, the heater was making the knocking noise....)
 
 

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