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Humming and Vibrating from 1 year old A.0. Smith Water Heater

by Mya Berger
(Edmonton Alberta Canada)

We never had this noise before but recently out hot water heater (A.O. Smith Model#GPD 40100)starting making a humming noise and which is sending a vibration through our home. The plumbers who installed it did a courtesy call today and what he ended up finding that there was no vibration on the right side where the cold water pipe is but the hot water pipe going into the hot water heater that is vibrating and then from there the pipes go up to the header and from there it is sending the vibration to the rest of the house. He put some rubber between the pipe and the header and this has lessened it somewhat but still does not solve the problem.

Why it is all of the sudden vibrating when it never did before? Can you give some insight into why this would be. Also the pipes going into the hot water heater are the copper accordion type. I read on the net sometime this pipe can cause the vibration, but still wouldn't explain why we never had it in the first place. Any help or suggestions would be much appreciated. Thank-you

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Nov 13, 2019
AO Smith banging noise
by: Sub

My water heater was making this loud banging noise. I ran a lot of vinegar through which seemed to be helping however the other day I replaced the valve in my bathroom tub and shower. This seems to be the best improvement. Two days and no loud noise.

Oct 01, 2019
Brand new AO Smith Gas water heater
by: tB

I purchased a brand new AO Smith gas water heater, G12-UT5040NVR 400, from Lowe's on Sep 2, 2019, and installed on Sep 24, 2019, just to replace a working 22 years old AO Smith water heater.
After installation, it had no issue in the first couple of days. On the 3rd days, I noticed loud humming noise, sounds like a whale, came from the bottom of the heater occurred occasionally and continue for 5-8 seconds when the burner kick in. The problem could easily be replicated by dialing the thermostat.
Very disappointed with this new AO Smith unit and based on what I've read, calling the customer service may not help at all. Nothing about this is posted on AO Smith's bulletin even though it seems like an old issue.
Just hope Lowe's will take it back.
Btw, Its build date is Jun 13, 2019

May 28, 2019
AO Smith 12year Gas 40gal 40,000 btu HUMMING
by: Anonymous

Sounds like same humming problem for me.
Very loud HUM for like 5-10 seconds every so often. So very disappointing.

I was so happy to get my new water heater installed and just minutes after firing it up I heard this loud Hum...

- I'm using the same gas flex lines as the original one and replaced the water flex lines with the same copper flex hoses. Other than that it is exactly as it was before and the last water heater never made a sound.

Can someone please confirm that this warranty fix works? And exactly what I need? This noise sucks... :)

May 14, 2019
Nothing but headache
by: Michael

Purchased a brand new A O Smith gas water heater G12 UT4040NVR 400 from Lowe's on 13 May 2019 the same evening after plumbing company installed
loud humming noise occurred occasionally continue for 6-8 seconds when burner kick in.
Plumbing company sends a technician for courtesy calls three times already.
unable to locate the problem.
call A O Smith Technical Assistant
877-8176750 many time the 1st person answer usually very courteous. However, always end up been transfer to another department back and forth going around the circle.
Finally, solution in my mind simply dumps this new $756.00, 40 gallons tank at Lowe's front door. with a nice little noted "DON'T TRUST AO Smith Product."

Feb 22, 2019
Recall Replacement Burner Loud Humming
by: Bob T

I recently received a postcard from A.O. Smith regarding a recall on the burner unit of my 3-year-old Whirlpool gas water heater. I had to call to get a case number. It took very long to get through to their customer service, I suppose since such a large recall.

They sent a technician to replace it and the loud harmonic humming started about a day later immediately after running hot water. The noise last about 5-10 seconds. Called A.O. Smith customer service about the issue and they suggested I have the technician come back and inspect the problem. He couldn't find the cause for the noise. Suggested getting another burner. A.O Smith sent another burner immediately, BUT, also sent the technician a metal spring type bracket that was installed below the burner inside the unit. This took care of the problem. No more noise.

The bracket was definitely an afterthought. It basically rests on the bottom of the water heater and is held in place with a piece of aluminum duct tape.

Bottom line, if you're experiencing this noise problem, ask for the support bracket up front and save yourself some time.

Jan 17, 2019
Sounds LIke a Whale
by: JACK

Just installed an AO Smith 40 Gal Natural Gas heater. Almost immediately it started emitting a humming sound after I used hot water. When the burner kicked in the sound started. AO Smith is sending a technician out to check it out. This is known warranty covered problem. No definitive fix is known so they will change out the burner.

My heater is not one of the Ultra lox Nox heaters subject to the recall.

Jan 12, 2019
Same Issue maybe
by: Anonymous

Sounds like the same issue for me. Brand new 40 gal, nat gas, 12 year unit, on first light, made what can only be described as a VERY loud harmonic about 10 seconds after lighting, and lasting 10 seconds. It happened at every lighting. Service came and replaced the burn head, and to my disappointment within 6 hours of the repair, it now does it randomly. Here we go on the roller coaster of repair. I have little faith now.

Apr 27, 2018
by: Anonymous

There is a warranty part that is added to the heater that fixes this completely.

Dec 30, 2017
Very Loud Hum from new A.O. Smith Water Heater
by: JC

My 3-month-old A.O. Smith Water Heater has also started making a very loud hum for 3-5 seconds every once in awhile. Very annoying! Any solutions?

Jan 16, 2016
loud humming from AO Smith water heater
by: Anonymous

Brand new AO Smith 50 gallon water heater sounds like a 747 landing in the house...AO Smith service rep came out and made the problem worst...now waiting for plumber that installed it to see what is the problem...and waiting for Smith service rep to come out a second time...almost ready to chuck the lemon and go tankless... :(

Sep 30, 2015
Brand New AO SMITH Hot Water Heater Noises
by: Anonymous

I have an AO Smith Hot Water Heater that was installed less than 2 months ago. Since right after installation, I have been getting random loud humming and vibration.

Dec 04, 2010
water heater nipples
by: tightspotvacuum brush

do you have galvanized nipples on the hot and cold water connections of your water heater. if the inside of the galvanized nipples have a blue plastic sleeve there will be a black rubber flapper. remove the black rubber flapper. sometimes they vibrate when water flows threw them.

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