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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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Oct 29, 2021
Rating
starstarstarstarstar 		New AO Hot Water Heater Makes Loud Humming Noise
by: Acehvacrepair

My newly installed water heater hums loudly and vibrated right away after firing and continues to make that loud noise every time it fires. The loud humming noise is located at the bottom of the heater which I’m sure coming from the burner. I reported to AO Smith and they will send a plumber to make warranty repair.
Apr 02, 2021
Rating
starstarstarstarstar 		No more "moan".
by: Don

Thank you AO Smith for a prompt fix of my water heater.
A local co. you contracted showed up on time and made the modification to stop the "moan" in less than 20 min. Wife is happy! I'm happy.
Nov 28, 2020
Rating
starstarstarstarstar 		Whirlpool Gas Water Heater noise resolved.
by: Jeff

Problem:
I just recently installed the Whirlpool 50T6-50UNG Natural Gas Water Heater and when the burner ignites and there is a flame, there is a vibrating noise that sounds like a "foghorn", which lasts for about 10 seconds. I removed the burner from the burner box and discovered that there is a bracket that is mounted towards the rear of the burner box area, screwed to the bottom of the water heater pan. The screw was loose and the bracket was sideways, as opposed to facing towards the burner. The bracket has two slots cut into it, that the burner flange would normally slide into so that the rear portion of the burner would be supported off of the bottom of the water heater pan. I re-aligned the bracket to face towards the burner and tightened down the holding screw. I re-installed the burner into the burner box, taking note that the rear of the lower burner flange was engaged into the bracket. "Fired Up" the water heater and no more noise. Simple fix….less than 30 minutes.

Analysis:
During assembly of the water heater, the screw that holds the bracket to the bottom of the water heater pan, the threads of the screw became stripped out (from using an air-powered tool) during assembly. Since the screw was loose, the bracket was able to rotate away from the burner when it was installed into the burner box. This allowed the rear end of the burner to rest on the bottom of the burner box, as opposed to being fully engaged into the mounting bracket. This is an example of poor quality control during assembly and inspection.
Nov 03, 2020
Rating
starstarstarstarstar 		Stopped foghorn noise
by: RnBee

Remember when we were kids and Dad would bang the top of the tv to get a better picture? A similar fix worked for me for my 40 gal no AO Smith. While it was moaning, I shook it, not a lot, then tighten the top inlet fittings. Just snugged up both. No more noise for many months now. Life is a mystery
Nov 02, 2020
Rating
starstarstarstarstar 		Is there a part # for the bracket?
by: Anonymous

Does anyone know the part # associated with the burner spring clip that's mentioned in a number of comments here?

The Customer Service rep at AO Smith I spoke with said she's heard of the fix, but thinks it may be a local plumber hack.

I'm having the same 6-10 sec of Foghorn humming on my Lo-Nox AO Smith water heater purchased under the Whirlpool brand from Lowes ( model # 50T12-40UNG400) mentioned by others here.

It ran quietly for a few years until it developed a different problem that led to burner replacement.

The replacement burner introduced the noise and it wasn't improved by replacement with another burner or the control unit that the AO Smith provided tech suggested.

I can quiet it down by putting the old burner back in, but that will reintroduce the old intermittent problem I was trying to solve.

I'm wondering if the problem is specific to a revision of the burner assembly device since my original one.
Jul 13, 2020
Rating
starstarstarstarstar 		Water heater humming AO Smith 40-gal Low NOx
by: Anonymous

Just installed a new A.O. Smith 40 gal. low-NOx water heater last week and makes the same noise. Just talked to their tech. support and was told there is a metal support bracket (for shipping) underneath the burner unit in the sealed chamber that sometimes comes into contact with the burner which causes the humming when the burner heats up and the metal expands to come into contact with the bracket. Wish I would have known this upfront as it could have been removed before installation when the unit was easier to access and to not have to deal with the noise for the past week!
Jun 07, 2020
Rating
star 		Foghorn noise
by: Enbee99

Just purchased the AO Smith 40 gal tall. The next day the foghorn noise started. Sounds like it is coming from the base of the heater. Mine was also a Lowe’s purchase. Any ideas on what steps I should take?. Mine has a 12-year warranty.
Feb 17, 2020
Rating
starstarstarstarstar 		HUMMING NOISE water heater
by: Christian

AO SMITH WATER HEATERS HAVE ISSUES WITH HUMMING NOISE. CALLED THEM, THEY GAVE ME A AUTHORIZED # CALLED PLUMBER WHO THEY GAVE ME CONTACT #. Find out it's a bracket on the bottom that holds the burner in place, that vibrates to make that humming noise. 20 min job seriously it's a job you could do yourself.
Feb 13, 2020
Rating
starstarstarstarstar 		Ao Smith foghorn noise
by: Anonymous

I just bought the ao smith g9-ut5040nvr last week Feb 2020 and since the beginning anytime it heats up, the foghorn moose call comes out. The first time I heard it, I thought the water heater was going to explode!!!! I called AO Smith who authorized a plumber to come fix it. Plumber came and "fixed it" and the sound is back again. I called AO Smith who is going to send me a new burner etc which is what the plumber had put in. My only other option is to return it which requires I disassemble, load onto a truck and dump it at Lowe’s. I certainly hope these parts will fix it! Please don’t get this make and model if you’re in Utah. It seems like a defect.
Dec 19, 2019
Rating
starstarstarstarstar 		Fog Horn sound
by: Anonymous

Our A.O. Smith 40 gallon water heater immediately after purchase from Lowe's made a loud foghorn sound every time water was demanded from it. A.O. Smith approved a "labor" charge for a plumber who replaced the burner and a fan-like structure attached to it and the problem is fixed. He said it was a common problem for A.O. Smith water heaters sold by Lowe's. Obviously a defect the manufacturer should have detected before marketing their product.
Dec 05, 2019
Rating
starstarstarstarstar 		AO Smith new - built Oct 2019 installed Dec 2019
by: Tom

My 40 GAL G12 UT4040 NVR made the super loud fog-horn hum sound I'm sure some of the others here are talking about. Called AO Smith support and they had a local plumber come look. Turns out they had seen this before and knew just what part to replace. It's a metal bracket with a spring holder on it. The new bracket has a wider spring. No more humming noise - at least so far. Nothing wrong with burner, although it needed to be removed to replace the bracket.
Nov 13, 2019
Rating
starstarstarstarstar 		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
Rating
starstarstarstarstar 		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
Rating
starstarstarstarstar 		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
Rating
starstarstarstarstar 		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
Rating
starstarstarstar 		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
Rating
starstarstarstarstar 		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
Rating
starstarstarstarstar 		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
Rating
starstarstarstarstar 		Warranty
by: Anonymous

There is a warranty part that is added to the heater that fixes this completely.
Dec 30, 2017
Rating
starstarstarstarstar 		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
Rating
starstarstarstarstar 		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
Rating
starstarstarstarstar 		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
Rating
starstarstarstarstar 		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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