Gas Hot Water Heater Noise
 

I have a gas hot water heater and I recently was in the garage when the water heater started up. I hear several low clunking noises as it first starts and then the noise stops as the heater goes through its heating process.

Water heats well, no leaks, expansion tank seems to be functioning. I have talked to others who have noticed similar startup noises.

Wondering if someone else has experienced the condition and knows the cause? Defective sacrificial anode comes to mind.

I remember similar noises with the gas fired water heater up North, I just took these as the normal thermal expansion noises. Heater was working fine several years later when we sold the house.

Sounds normal to me. Thermal expansion and sediment moving around.

Normal noises

It is the sediment being forced up by the heat. It is not normal if you have been draining your tank monthly. Monthly tank draining is covered in your owners manual. People mistake this as 'normal' because few bother to maintain their water heater. Sediment does impact your HWH tank's life expectancy, this is why it is in the manual.

Very hard water here which produces lots of sediment, probably the cause of the rumbling and knocking. I drain 5 to 10 gallons out of the bottom of my tank every 9 to 12 months and am astonished at the amount of white crystals that come out.

If you drain your tank, be prepared for the drain valve to drip after you close it, from sediment left in the seating area. I changed out the cheap globe valve to a full port quarter turn ball valve and no more problem.

Thanks for the responses. Has anyone changed out the Anode ? Supposedly a consumable.

I have. It took some effort as the rod was quite corroded. Most tanks use an aluminum rod. I replaced mine with magnesium. Magnesium helped with the sulfur smell in the water, this was in a different state.

Good article on the how and why of draining the water heater:

Why Is My Water Heater Making a Knocking/Rumbling Noise?

I had noises from my HWH for about 8 years, this was in Bucks County, Pa. very hard water, similar to T.V. It never leaked and remained working fine (except for the noise). That HWH lasted 18 years. I finally did change it out, but those noises are related to a build up of sediment. Not harmful in any way, but causes your heater to be less efficient.

I’m have this noise issue with my new furnace! The AC company tested the gas pressure coming into my house and found it double what it should be. First question he asked was does my hot water tank make noise? And what about the gas flame on my stove? Gas company coming out today, to check. Gas regulator either set too high or bad regulator. Have you had the gas company check the gas pressure coming into your house?

How much does it cost to have a rod replaced and how long do you wait before doing it? Will this allow the water heater to last longer?

Wish we could drain our water heater! However, when Mike Scott Plumbing installed it (8 years ago when the house was built...we’re 2nd owners) they left the valve turned down into the pan. Impossible to get at the valve now.

Had same problem with hot water heater ,got 90 degree bend washing machine hose take 5 gallons out every year before I go back north still like new inside water heater only last 5-6 years if just left alone. If you have to replace high efficiency model more expensive but cheaper to run cost in 3 years would make up difference

Not a difficult fix. Make sure your pan is plumbed to the outside. Turn off your water to your house and open faucets in sinks and outside your home to drain all the pressure and water out of the lines. Take a wrench and unscrew the valve on the water heater slowly allowing the water to drain into the pan. This will take a while so do this when you are not going to need water for a while. You can now either replace the valve with a different style or use the old one positioned in a more convenient position. Be sure to use pipe wrap and have someone standby when the main water is turned back on.

Ohiobuckeye
 

Good suggestions, but you could try & drains about 5 gals. out of it to see if you have sediment on the bottom of the tank. Doesn't hurt to try.

I have never drained a water heater. Most people don't. I would be concerned that the valve will start to leak because of sediment clogging it up. Also, I don't think that opening the drain valve is an efficient way to remove sediment unless you do it every month or so. If you have years of sediment built up, I believe it will mostly be caked onto the bottom of the tank, and will stay in the tank when you open the drain valve.

It cooler now . At times when cold water enters hot water sometimes you'll get a banging sound

When we moved in, popping and thumping sounds seemed to be coming from the attic. We thought it was squirrels because we have a lot of squirrels and it sounded like little feet running and chasing. We called an exterminator and he saw no signs. The sound only occurred at night because that's when we ran the showers and dishwasher - so it seemed logical the squirrels were coming in for the warm dry attic. I finally put a game camera in the attic but got no results - not even a mouse. Then I was in the garage one day when the clothes were being washed. The washing machine was louder than the noise in the house, but in the garage near the water heater I could hear the bubbling. Mystery solved!

Up north I would drain some water out of my water heater twice a year to remove some sediment. One time I did it I couldn't close the valve all the way and water kept coming out no matter that I closed the valve as far as I could.

I had to rush to the hardware store and I was able to get a cap that I screwed on the end of the valve to stop the water.

I'll never drain a water heater again.

No idea what it costs as I did it myself. The anode was $20. Yes your tank will last longer, the idea is the anode corrodes and not the tank, so the tank that would last 18 years otherwise lasts 30 years with proper maintenance. You should do this every 3 to 5 years.

I will add "my tank lasted XX years" posts are useless. Those tank are not here, they were some where else with different water. I further argue that products made 20 years ago used better materials with longer warranties than what is in your current home

Gas valve starting- normal
 

When it’s not heating, the gas is switched off. When it needs to heat the water, it switches a small amount of gas through and creates a spark to ignite it. If it lights, the boiler detects this and opens the main gas valve, another clunk. If, for some reason, the gas supply is absent, the boiler senses the absence of flame, and shuts itself down. All good stuff.

agree.. happened to us this summer up north....had to replace the anode, covered with sediment....then had to flush water heater a couple of times. finally noise disappeared.

No that’s in your operating instructions manual. I lived in a city before that you had to hook a hose on nozzle valve at the bottom & I would get lots of lime build up out of it. So if you want your hot water heater to last drain some out or you’ll be replacing your water heat more than you want!

Here is a quote from the Rheem water heater manual:

"It is suggested that a few quarts of water be drained from the water heater’s tank every month to clean the tank of these deposits."

I don't follow this instruction, and I seriously doubt that very many people do. I wonder if any of the home watch or management companies offer this service?

Dream on my friend! I have seen a home watch company, who is widely recommend on this site, not enter my vacant home for three months running. First month no pictures, second month exterior photos, third nothing. I have a wireless alarm and I get a notification if they open a door any door, including the garage door. If they can't even bother to do a walk through they certainly would not touch the water heater.

Yes I got billed every month.

What part of the villages do you live in?

First , I started this topic and I thank all for your advice. I have a 13 year old water heater that had never been drained and was providing noises upon startup. I decided to drain and replace the drain valve with a 3/4" NPT Ball Valve. Did my homework to check out parts and sizes needed and made sure I had all tools and consumables.
Shut off gas , water inlet valve, opened hot water sink faucets, connected hose to drain valve , opened valve and got nothing. That was not in my plan. Long story shortened, needed to turn faucet off and open water inlet valve. That pressure got things started but slowly. Shortly after reopened faucet and Pressure relief valve and closed water inlet. That got the draining going. Still had to poke around the open drain valve to keep it flowing.

After draining , took off old gate valve and installed ball valve. Noticed a lot of white mushy sand on bottom. Did several short flushes (about 8 ) to get as much out as possible out before refilling. Closed valves, refilled, restarted. No noise and water heated within an hour.

Other than a several gallons of murky water, all of the remaining sediment looked like a white oatmeal. When rubbed, outer coating appeared sudsy and the interior very fine sand. Best to have it gone, and with the new ball valve , future drains will be a snap and coming more often. Don't like the looks of this stuff.

Mine appears to be somewhat different as it has a permanently lit pilot. When the thermostat detects that heat is needed, the gas valve is opened until heat level is reached. Gas is then shut off,, but pilot remains on.

Did you say you opened the temperature and pressure (T&P) relief valve at the top of the water heater? Hopefully, you got a lot or water coming out of the discharge pipe. That is a safety device, which may also be clogged and non-functional. If you plan to keep a 13 year old water heater for an extended life span, you should test and replace the relief valve if it doesn't work properly. Lift the metal lever to test it. If it malfunctions, the water heater could experience excessive temperature or pressure and could explode. Just a suggestion, because most people are replacing the water heater after 13 years. Also, 13 years ago, expansion tanks were not required, but they are now. An expansion tank would help to maintain a constant water pressure in your house, which will protect your plumbing fixtures from experiencing excessive water pressure and possible damage.

Very definitely opened pressure relief valve, which is what allowed the tank to start evacuating water. That was recommended because of a closed system as you suggest. My pressure relief valve was replaced several years ago after it successfully responded to a failed expansion tank. My pressure relief valve is not on top but on side about one foot from top. And I doubt if simply opening it, would verify that it would verify that it can functionally protect from excessive temp or pressure.

Also, valve clogging would seem to be more likely lower in the tank where the sediments accumulate as they were in my tank.

I should note that I really was only trying to express my experience in draining the tank, and not trying to express that I know anything else. That was the whole purpose of my initial opening of this chat.

It sounds like you have everything covered. But, personnally, I wouldn't feel comfortable maintaining a water heater for much longer than 13 years. I believe that most people never do any maintenance on their water heater and they replace it when it either fails or leaks. That is usually after about 10 -15 years. Fortunately, in The Villages, most water heaters are located in the garage, where they don't do much damage when they leak. But, they really are not very expensive to replace. Good luck.

Thank you for the update. You have made a good case for the rest of us to drain the tank at least once a year.

:) And if yours is GAS - TECO has a energy saving rebate program. When I replaced mine it was close to free! :MOJE_whot:

Did you know that a tankless heater like those south of 44 require MORE Maintenance than a tank heater?

The maintenance is isolation of the heater via the valves below it and running vinegar through it by a pump for 30 minutes. Unlike Retired guy and most everyone I maintain my water heater. I am surprised that no one seems to be aware of this. With no maintenance expect less than13 years from one, with maintenance expect at least 20.

Actually my tankless water heater (Navien) is really easy to do a PM on. Turn off the unit. Turn off water supply valve. Drain it. Remove and clean recirculation and input water filters which unscrew from the bottom. Rinse off and replace.

Open up the panel and remove and clean air intake filter. Reinstall and replace panel.

The only thing that takes any effort at all is flushing out the heat exchanger. But if you do it while you have the recirc and input water filters removed you're already halfway there.

Oh it is easy, it is even easier to maintain a tank heater. Consider this thread, the vast majority of posters had no idea maintenance is required at all. Most who offered advice had it wrong. To make matters worse some of these guys are engineers and should have known better..

The personal observation of what is inside the tank that comes out when drained is enough to make a believer. It is not only tank maintenance, it is water maintenance. The tank is designed to extract hot water from the top and it is natural for the sediment to settle to the bottom. However, mixing of the layers is occurring.

I actually had difficulty in draining my tank (First time in 12 years) due to the thickness of the sediment clogging the small gate valve. Actually had to open water inlet valve and close inside faucet to pressurize tank to expel the sediment to get the process to start draining. That issue and cautions of drain valve leaks persuaded me to change drain valve to a 3/4 inch ball valve . That will make future draining a snap.

I commend people who want to drain their water heater on a regular basis to increase efficiency and maintain it longer. If you do, I would recommend that you do it on a regular schedule, and be prepared to deal with a leaking valve it that happens. At a minimum, have a plastic or brass cap and washer available to screw onto the end of the drain valve to stop a leak. Also, it is important to periodically make sure that the T&P (temperature and pressure) relief valve is still operating by lifting the metal lever. This is especially important if you do not have an expansion tank. And, if you replace an old water heater, make sure that the contractor installs an expansion tank, even if you didn't have one on the old heater. It will help to maintain a safe and constant water pressure in your house.