How to Clean the Sediment from Hot Water Heater?

alwaysfixinJanuary 27, 2007

I am certain that my gas hot water heater isn't making as much hot water as it used to because of sediment and lime buildup in the tank. The heater is 5 years old, 50 gallons. I'd like to get it cleaned of that buildup. But who do I call to get the tank cleaned? I am not handy for that kind of thing, and the tank is in a very narrow space. Do I call a plumber? An HVAC person? And what would that kind of job cost? Thanks for your advice.

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Well, for starters, you can drain the hot water heater. You just need a garden hose to attach to the drain knob (it's like a hose bibb), turn off the water to the tank, open at least one hot water outlet (i.e. turn on the hot water in the sink closest to the hot water heater), and the open the knob. Once the tank empties, you can knock off some of the deposits still stuck inside the tank by turning the water back on for a few seconds (repeat a couple of times until you can't detect anything other that water draining from the hose).

    Bookmark   January 28, 2007 at 2:06AM
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Thanks for your response and explaining how it would work. If I want to hire someone to do this, do I hire a plumber, or an HVAC person? And what would the job cost (ballpark)? Thanks for your advice.

    Bookmark   January 28, 2007 at 1:41PM
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Turn the gas/electric off to the water heater. Leave the cold water supply valve on to the heater. Hook a hose up to the boiler drain on the water heater and turn the valve on. Turn the handle back and forth; there will be grit in the valve assembly and you need to establish good flow before shutting the cold water inlet valve off to the heater.

Once established, shut the cold water inlet valve off. THEN, go around and open all hot side ONLY valves in your home so you can break vaccum and allow the hot water to drain from the tank. That boiler drain off the tank is the lowest point of your potable water system so you need to allow it to drain completely out.

10-25 minutes is the norm for proper draining; you should be able to "shake" the tank to determine it is completely empty. Just because it stops draining does not mean it is empty most times.....usually dirt/debri blocked the pathway to the hose.

Once you are completely sure that the tank is drained, go ahead and turn the cold water inlet valve back on and let the tank drain a bit, then shut it off. "Stomping" on that hose while there is established flow coming out of the hose will purge the tank by a rush of water hitting the bottom and scurrying up the debri to go out of the tank.

Once you've shut the boiler drain to the tank off, LEAVE THE HOT SIDE VALVES OPEN THROUGH THIS ENTIRE PROCESS. So many people think you turn those hot side valves off before filling the tank and that is completely wrong. Air is compressible, water is not. You compress air in your lines you'll end up blowing out faucet aerators next time you go to use the fixtures.

Leave all hot side faucets run until there is a steady flow from all of the faucets without distortion. Once the water is steadily flowing without air, shut the faucets off, turn the electric or gas water heater back on.

It's an hour procedure, maybe an hour and a half, expect around $100-$135 for the procedure.

    Bookmark   January 28, 2007 at 2:14PM
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I am starting to wonder if my initial diagnosis of sediment is correct. I just read the other thread "No Hot Water-Heater 8 Months Old", and Lazypup's response in that thread made me think. He said, "As the incoming water temps fall the water heaters ability will drop off proportionally thus you will always see the lowest performance during mid winter." Up until recently, we've had a mild winter, but it has been in the 20's lately, and today, only about 16 degrees. Perhaps that is why I am noticing that my hot water heater isn't making as much hot water as previously. I think I should wait until the weather warms up a bit, and then see how much hot water I have.

How common is the sediment problem? And how quickly can it happen to a hot water tank?

    Bookmark   January 28, 2007 at 4:47PM
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I have drained the sediment from many heaters. I leave the supply pressure on and open the drain valve (with hose attached). The water and sediment rushes out. When the water runs clear, I close the drain valve. I believe that shutting off the supply pressure insures a very slow outflow rate and leaves more sediment in place in the heater since no water flow velocity exists. And why continue draining after the water runs clear, what does that accomplish? If the other methods are better, please explain why.

    Bookmark   January 28, 2007 at 5:02PM
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Thanks for the follow up on my response. I forgot about the part on turning the system off. FWIW, I find it good enough to turn the temp on my gas hot water heater all the way down so I don't have to kill the pilot light.

Hire out a job that isn't much more difficult than using a lawn sprinkler?

Yea, I realize it can be a little scary messing with these mechanical things at first. But this is a simple enough job that you shouldn't have any problems if you just listen to the instructions given here.

And regardless of what you read in the other thread, IMHO, if you've got a 5 year old water heater that's never been drained before, it's past time to do it, especially if you live where the water is hard. At a minimum, it should boost the efficency of the water heater, because surely there is some buildup that a flush will get rid of... not all of it, but an improvement.

    Bookmark   January 29, 2007 at 2:03AM
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I have a hot water heater (30 gallon) that came with my manufactured home. It stopped giving me hot water. I have well water and it has a lot of calicum and other stuff in it. Called a local handy man and he told me to put in 2 bottles of CSR, let it sit over night and then drain it. Good idea or not? If OK, how do I get the CSR into it. Note, the overflow pipe was caked solid with gunk but I used a re-bar and cleaned the pipe out.

    Bookmark   March 7, 2009 at 4:41PM
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Fully cleaning the sediment and calcium deposits from a gas water heater is not nearly as easy as some make it sound. I have two three year old gas water heaters (one 74 gallon and one 35 gallon). I have drained them in the past, and the water always looked clear when I finished. I always drained them completely, yet never got much sediment out. Despite my attempted maintinance, the water heaters got louder and louder over the past three years (loud poppong and rumbling sounds while heating). The sounds have become so bad that I was seriously thinking about replacing both heaters with tankless models.

This past week I installed a whole house water softener along with a whole house carbn fileter. In a last ditch effort to avoid replacing my water heaters I drained my large tank again this week. During the process I got a little sediment out but as was the case in the past, not much. There was no blockage of the drain, and the water ran very clear. Looked like everything was fine. I put everything back together and turned on the heater yet the popping and rumbling sounds were as bad as ever. Last night after work I went at it again. I drained the heater again, again the water ran clear, virtually no seniment. I then removed the drain. Using a flashlight I peered through the drain hole, and things did not look too bad but I knew that something was up. After a few minutes of looking I figured out why all of my prior attempts to drain the sediment were innefective.

The botom of a gas water heater is a dome that is highest in the center where the exhaust flue sits, and lowest along the edges. The drain sits about two inches above the lowest edges of the bottom of the dome, and as a result simply draining the tank will never allow you to clear the sediment/deposits. Instead, those deposits simply settle into the two inch v-chanell at the bottom of the dome along the sides of the tank. Draining the tank alone is almost useless, even when the water runs clear.

I took my shop vac and created a flexible attachment using some 1/2 inch clear plastic hose and several pvc and funny pipe fittings. I stuck the hose through the open drain hole and used feel (because you cant see anything) to get the hose in the groove. I would then fish around with the hose, moving it back and forth, and side-to-side to try to find the debris. There were literally pounds of sediment and calcium deposits along the bottom outside edges. The sediment was not completely hardened, although there were plenty of larger pieces that kept clogging my suction hose. I spent four hours adding a little water by opening the cold water inlet (don't add too much at one time or it will just run out of the hole), and then fishing around, and sucking up the debris. I filled up my shop vack 6-7 times, and after geting rid of the filth water ended up with a quart or so of solid calcium and lime deposits. I quit around midnight and re-assembled the heater. I did not get everything but wanted to see if I had made progress. After re-assembly I filled the tank, re-lit the pilot and turned it on.

Sucess at last. There were a few popping sounds but they were very quiet and could only be heard standing right next to the heater. I am going to clean out the smaller heater tonight after work. I am sure it will be another late night.

This is simply the nature of the beast when working with gas water heaters. The shape of the tank is necessary because the heat and gas from the burner need to be directed up through the center flue. It would be nice if the drain were at the bottom, but I assume that it probably cant't be located there because it would compromise the integrity of the tank if it were right on the bottom edge. The nice thing about electric tanks it that they do not have a domed shaped bottom, so it is much easier to suck out the sediment that sits below the drain.

The bottom line is that you can fix your noisy gas water heater, but it is going to be a nasty, time consuming job. In the end, I am gald that I figured it out - better than buying new water heaters after just 3 years.

    Bookmark   March 31, 2010 at 1:50PM
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After I drained all water from my hot water tank,shut off drain valveand relieve pressure valve then turn on cold water vale.because of large amount of sedimentation and turbid color of drained water,I decide to drain some more water and found that the water is still quite dirty and turbid after all those water from the tank had been drained.Please tell me what should I do.thank you very much.Sam

    Bookmark   December 26, 2010 at 10:33AM
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our hot water heater stopped working. went downstairs and seen the pilot light was off. Got the pilot light to work, but when we turned the dial to "ON" the pilot light goes off. What should we do ?

    Bookmark   April 16, 2011 at 3:11PM
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How would you store a water Heater for six months

    Bookmark   August 17, 2011 at 2:21PM
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Last two posters.....your response unrelated to topic of this thread. Suggest beginning new threads.

    Bookmark   August 17, 2011 at 2:27PM
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I like to drain mine, seal it up and partially fill with water and let the air compress. When you open the drain valve, it REALLY stirs stuff up. I finish by refilling while purging air from the top of the tank with your hot water taps open.

    Bookmark   August 17, 2011 at 9:10PM
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I'm installing a new HE 40 gallon electric water heater (we don't have gas) & want to install a hot water recirc pump at the same time. We have a few long runs in the plumbing so I think this product will help get hot water to the fixtures quickly. From what I see on the market these two (Watts & Grundfos) seem to be the leaders in this market. I don't mind spending a little more to get the best as I want it to last, perform & not give me any problems. Does anyone have any suggestions on these two pumps? Thank you in advance...

    Bookmark   September 15, 2011 at 4:28AM
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Sorry about the above thread, I made a mitake posting my question on the site.

    Bookmark   September 15, 2011 at 4:36AM
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Some of my experiences cleaning sediment out of a hot water tank, in this case, powered by electricity:

The first time was about three years ago. I started to drain the tank in preparation for replacing the burned-out lower heat element. I had attached a garden hose as most instructions tell you to do. At first the water (quite black with sediment) drained out as expected, but in a minute or two, it slowed to a trickle; I was sure the tank could not yet be empty. I soon discovered the outlet valve was plugged, and eventually removed it to get the water running again, directing it to the basement drain across a plastic sheet fashioned into a sort of trench with sides made of some short 2x4s and bricks under the plastic. The sediment came out in chunks up to 3/4" across. They were easily crumbled, but nevertheless had been solid enough to impede water flow through the valve.

I reattached the valve, but felt that wasn't good enough. Following some advice from somewhere on the web, I purchased a brass nipple and ball valve from a local plumbing store and installed them to replace the original plastic valve. The inner diameter was now larger and without bends, so less likely to clog. That helped quite a lot.

Meanwhile I had removed the old element. So I had an extra access hole available. I rigged up a piece of 1" plastic pipe to the end of my shop-vac hose and was able to insert that into the element hole and pull out a substantial amount of sediment. I also was able to insert a garden hose into the same element hole and flush out more sediment through the new valve outlet. I'm sure I never got it completely clean, but at least the escaping water was now clean and running freely. I installed the new heat element, and all has been fine since then, except of course, I would like to be able to do a proper regular cleaning without removing that heat element.

Since that time, I have tried to remember to flush out the tank every six months or so. It hasn't been completely satisfactory, but I think if it's done regularly, at least the build-up won't be too great. Just today, I had some trouble even with that better brass valve. It became clogged as the other one had before. This time I found a good remedy in a length of 3-wire 10-gauge soft-coated electrical cable. It seemed to have just the right amount of flexibility and stiffness. Poking that through the valve and into the tank removed the obstacle. I'm thinking that for my next cleaning, I will try to attach a piece of narrow tubing to the end of a garden hose and push it into the outlet valve to do some back-flushing.

At least I'm lucky in a way to have an old unfinished basement with a concrete floor and a big drain hole. Spills are not much of a problem. I'm very happy too with my makeshift "trench" which works very well to take the outflowing water to the drain. It cannot clog like a hose, and I'm even able to make a dam to catch the sediment by means of a simple fold in the plastic sheet.

    Bookmark   August 14, 2012 at 2:20PM
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I always remov the plastic drain valve form new water heaters, install a bronze nipple and a full bore ball valve with a garden hose thread on the output side.

With a full bore valve it is a lot faster to drain things down and a lot more crud coems out.

I have had enough of the factory valves fail to close after being opened and then had to screw in nipples and valves as water gushes out (the 'vacuum lock' is rarely 100% effective, especially on multistory houses).

    Bookmark   August 15, 2012 at 11:29AM
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I agree with the the last posting. You should check on whether you have a plastic valve. If you do you may not want to start draining a water heater that is more than a 5 years old. They are notorious in giving up their functionality once you try to touch them.

It is best to do it once a year or to skip it altogether and let the water heater go down its own path of destruction.

If you mess with it in mid-life you may shorten its life significantly if the valve crumbles.

    Bookmark   August 20, 2012 at 4:39PM
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I like to isolate the tank, then turn off the drain valve. Then I refill it without burping out the air. When the drain is opened again, the compressed air aids in powering the sediment out.

    Bookmark   August 21, 2012 at 5:04PM
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Step #1 Turn the Electricity to the Hot Water Heater Tank Off
The first step to drain the tank is to shut the heater off. It's probably wired directly to your breaker box so you'll have to find the switch and shut it off there. Doing this will prevent the heating elements from becoming damaged when they are no longer submersed in water.

Step #2 Shut the Cold Water Valve Off
Look for the cold water inlet valve which will be located directly above your electric hot water heater tank. Shut this off as you don't want any water coming into the tank while you drain it. That would just be a waste.

If there is no cold water inlet valve located there, then you'll need to shut off the main cold water valve.

Step #3 Vent the Hot Water Line
Turn on the hot water faucet in your bathtub. This will help vent your hot water heater tank so it will drain quicker. Any water that's still in the line will come out, but it should taper off, then completely stop after a minute or so. If not, then the heater isn't properly shut off. Recheck your breaker box to make sure you flipped the right switch.

Step #4 Drain the Heater Tank
For this step, you'll either need a long garden hose and access to a floor drain, a sink with a drain, or the outdoors. Locate the drain valve on the bottom front of the unit. Securely attach the garden hose to the valve. Place the other end of the hose at a drain or take it outside.

Slowly open the valve and allow the water to drain from your hot water heater tank. Make sure you have the hose attached securely. If it's leaking, turn the water off and reattach the garden hose.

Safety Note- Remember! This water is normally very hot! Don't let kids play in it if you take the hose end outside! And don't let your pets drink from it!

Step #5 Flush Your Hot Water Heater Tank Out
Once the water has quit running out of the tank, shut the drain valve off. Shut the bathtub faucet off too. Then, turn the cold water inlet valve- located above the tank- or the main water valve back on and let the tank fill up for about five minutes.

Shut the cold water off again and open the drain valve at the bottom of the tank. This shot of additional water will help remove any sediments that may remain in the bottom.

Note: If the water that's draining out is still sandy, cloudy or otherwise discolored, repeat step #5 until it runs clear.

Here is a link that might be useful: Water Heater Maintenance

    Bookmark   April 18, 2013 at 3:31PM
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