The symptom is inconsistent hot water temperature. We just purchased the house about a month ago. I decided to drain the hot water tank (natural gas) not knowing when it was done last. The hot water heater is 6 years old. Trying to drain the tank through the drain valve is giving me fits.

I closed the natural gas valve and also turned off the gas control knob. I then closed the cold water inlet valve. I opened several hot water faucets. I opened the drain valve on the hot water heater. It drains for about 5 seconds with low pressure/water volume then stops. If I turn on the cold water inlet valve, I get a lot of pressure and volume - 2 gallons in about 15 seconds or so (50psi). There is definitely sediment (similar to white sand). Once I turn off the cold water inlet valve, the water stops coming out of the drain valve.

Do I have a bad drain valve or a different problem?

I drained the system with the cold water inlet valve open for several minutes. Still can't get the hot water tank to drain without cold water inlet open. Again, I have opened the hot water faucets but still nothing.

Thanks for any feedback!

What you need to do is flush the water heater. Draining it won't do any good as far as getting the sediment out. You are on the right track. Hook a garden hose to the drain and simply open the drain. You want to leave the water supply on to the heater to flush it. Let is run as long as it takes for the water to clear up (no more sediment coming out).

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There is definitely sediment (similar to white sand)

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Unfortunately that sounds like a deteriorated dip tube.

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Again, I have opened the hot water faucets but still nothing.

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Most single lever faucets do not let air in very well. If you really want to drain, open the T&P valve.

But as Lee said, flushing not draining is what you want to do to remove sediment.

Thanks for the responses mgd77 and hkstroud:

I still have a problem with sediment. I used the method mgd77 suggested then filled the water heater back up with water and used the hkstroud method. Then I tried a few more things:

I turned off the cold water inlet and then removed the entire drain valve and unloaded the tank 2 gallons at a time - putting the drain valve back in to stop the water between emptying the bucket. I was still extracting sediment with each bucket full of water. After about 5 buckets, I used the water hose method using a new drain valve (and still saw white clump sediment) to empty all 50 gallons out of the tank.

Then I tried a few more methods to get the sediment out. The one that was most successful: I removed the new drain valve, put a bucket underneath the water heater to catch the water that didn't make it in to the bucket I put at the mouth of the drain opening that caught most of the water. I turned the inlet cold water on for 4 seconds and turned it off. I did that for about 3 cycles which filled up the 2 gallon bucket. The water was clear but I still had clumps of white sediment at the bottom of the bucket. I emptied the bucket and did that same process about 8-10 times.

I know there's still sediment at the bottom of the water heater. Is there a more effecient way to get those clumps out?

I did some research on the dip tube. I don't think a broken dip tube is my problem because the white sediment is not plastic - its like a clump of sand that easily breaks apart when touched. I will keep an open mind on the dip tube if the water a) doesn't stay hot while taking showers over the next few days, b) the water isn't a consistent temperature day to day.

I found this site. Lots of great information. I like steps 13-15 using a wetvac.

How to clean sediment out of water heater

If I still have problems, I will go this route. I also have a waterproof snake camera which should help. Will keep this thread updated.

Maybe I 'm analyzing this too much. But at the very least, it helps me understand the operating characteristics of a hot water heater.

This morning (5 hours ago) I took a shower and it was great! Hot water - no problem.

About 30 minutes ago I drained about 1 gallon of water from the hot water heater via the drain valve. The temperature was only about 100 degrees. I have the setting on the hot water heater to "A" which should be about 130 degrees. I went to the kitchen faucet and turned on the hot water. After a few minutes, the temp was 130 degrees. Is it normal for that much of a temperature gap between the bottom of the hot water heater and the water that comes out of the water heater? I just now took another 1 gallon out of the water heater via the drain valve and it read about 114 degrees. Thank you for any reply!

I'm still looking for a complaint here. The water heats and you can power flush the tank. Where's the problem? The fact that without water pressure your system's air locked and it won't drain? Simple. You're air locked on the hot water faucet so open up the T&P valve on the heater, If that's what bothering you. As for sediment on the bottom of the tank it sounds like calcium carbonate and not part of the dip tube. This will cake up and insulate the flame if you don't flush, not drain, your heater on a regular basis.
When sedimate builds up on the bottom of the tank I drain all the water out of the tank and remove the boiler drain. I then take a wooden rod and break it up where I can flush it out.


For long life and fewer troubles you should keep your heater clear of mineral build-up by FLUSHING NOT DRAINING on a regular schedule.

Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run until the water runs clear. You will see a spurt of red,(rust) followed by white or yellow grains,(lime or calcium carbonate). This shouldn't take more then a few minutes.

Do this monthly to keep it clear. Now flush out your hot water lines Be sure you put them back together the same way you took them out. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps and thank you for rating my answer, Tom

Hi Todd

Yes, it certainly wouldn't be considered abnormal to get a temperature difference between water at the bottom of the heater VS water coming out your faucet! Here, cold water is fed into the bottom of the water heater VIA that dip tube that has been discussed and then as water is heated it floats towards the top and is dispersed to the house as needed. As more hot water goes out to the house, cold water enters the bottom of the heater which makes even fully heated water at the bottom of the tank warm again, right?

Now, in terms of everything going on here...

I think you have removed a great deal of sediment AND the precipitate that forms when minerals in your water interact with the ANODE ROD. At this point, I would continue to flush the water heater on a regular basis and I wouldn't worry too much about this any more!

In the future, especially when you get a new water heater, be sure to flush the water heater regularly ANS for increased life of the tank, change out the anode rod every 5 years... almost guaranteed to at least double the life of your water heater!

Mark

Thanks for the replies. I still have the issue.

I drained the system today and removed the drain valve. I sucked the remaining water out with a wetvac and looked inside with a flashlight and my snake camera. The flash light worked well enough. I saw a small pile (1/4 cup) of white sediment in the back left section of the water heater and I used the wetvac to suck it up. The bottom of the tank looks good. No rust, etc. I opened the cold water inlet and filled the tank back up with water, opened all hot water faucets until all the air blew out and had a stready stream of water. I then shut the faucets off, opened the gas valve, light the pilot, set the temp to 130 degrees and now the burner is on heating the water.

Let me restate the problem. I could have nice hot water for the shower one morning and the next morning it is luke warm.

@speedball1: That is my complaint. I'm trying to figure out what/where the problem is.

@massplumber2008: I understand the process of cold water entering the bottom of the tank and the hottest water rising to the top and out to the faucets. Help me understand the working of the water heater. The bottom of my water heater is very clean. I have a gas water heater (State Select model PR650XODSV2) with one burner on the bottom. The thermostat seems to be about 4 inches above and to the left of the drain valve. If the thermostat is set to 130 degrees, where physically in the tank is the water temperature taken? Under what conditions or temperature range does the burner kick in to heat the water? If the thermostat is set to 130 degrees, what should the temperature be of the water at the bottom of the tank once the burner shuts off?

Given I now have a clean tank bottom with little sediment, where should I look next?

Thanks again for all the replies!

Edit: A little more feedback. We've had this problem since we bought the house a month ago. Two weeks ago I replaced the PRV and set it to 50 psi. A week ago I installed an expansion tank (WATTS DET-12). See picture below:

http://www.emmershy.com/waterheater/exptank.JPG