Water heater flushing questions

Old 04-21-20, 10:18 AM
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Water heater flushing questions

I have a 1-year old AO Smith electric hot water heater. With social distancing making it a good time to flush it, I went at it. I've had water heaters for many years so I know the basics. The water was cloudy through the entire 50 gallon draining. When it was empty, I turned the water on and continued to drain. The water got very cloudy with calcium (I think) collecting at the bottom of my pitcher.

I assume turning the water on caused sediment at the bottom of the water heater to kick-up. Now the water is more cloudy than when I started.

BTW, I have well water. My softener broke but I didn't realize it right away and didn't have it working for about 6 weeks. (I thought I had salt issues.)

My questions:
  • Am I correct? Did sediment from the bottom kick-up?
  • Should I continue to drain while I add or should I stop draining, refill and do it again?
  • Or should I allow the sediment to settle back at the bottom and redo it again?
  • Should the water be clear (like the cold) before I stop?
Old 04-21-20, 11:23 AM
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Sediment on the bottom of the heater is often kicked up.

I don't "drain" my water heaters. I flush them. I leave the water heater on and the water on and simply open drain/flush valve at the bottom. The water pressure helps the flushing process go quicker and you can use a garden hose to direct the water outside.

I flush until the water is mostly clear and free of chunks. If you are still getting stuff out that means there is more still inside the heater so as long as you're at it you might as well get out the most you reasonably can.
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Old 04-21-20, 11:28 AM
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I don't think the water was cloudy from the water heater. More likely the well water was cloudy.
Emptying a 50 gallon WH should be more than ample to clean the tank.

When I flush my tank...... I turn off the heat and flush out approx 15 gallons. Typically the sediment comes out in the first 30 seconds. I'll also close and open the drain valve several times to get the water to slosh out the minerals.
Old 04-21-20, 11:45 AM
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PJ, I'm positive the cloudiness is from the water heater. I'm using a hose to outside, checking every few minutes by filling a 1/2-gallon glass pitcher. The water was cloudy at the start, then was fairly clear. When the water heater was empty, I turned on the water and continued to drain. That's when I got white powder collecting at the bottom of the pitcher. I assume I stirred up stuff at the bottom of the heater.

Thanks to you and Pilot Dane. Much appreciated. I'm going to drain / flush one more time and be finished.
Old 04-22-20, 06:45 AM
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Important step 1. Before you start, turn off the water heater heat. Not just to vacation setting,.

Different methods you can use alternately ever few months or even a few days apart.

Choice 1. Flushing out the water heater drain. Leave the water on. Don't use hot water for several hours to let the sediment settle. Open the drain valve. Yes the sediment will be kicked up into the water but most will stay near the bottom of the tank. Yes, it sometimes requires several bucketfuls before the water runs clear.

Choice 2. Gravity draining. Turn off the cold water inlet above the water heater (or turn off the main house water). Open a hot faucet upstairs. Open the heater drain valve. This drains out the sediment kicking up very little. But sediment around the edges won't come out.

Choice 3. Flushing the water heater via a faucet. Leave the water on. Open a hot faucet upstairs. Not recommended because sediment won't come out until after it has been kicked up throughout the tank and many gallons have to be run out.

If it has been years since you last flushed the water heater, we suggest waiting several hours, doing choice 2, and 15 minutes later doing choice 1. Two days later repeat.

If you flush the tank regularly, doing choice 1 and choice 2 alternately every 6 months should suffice.

Do not turn the water heater heat back on until you have fully opened a hot faucet upstairs and nearby and watched a torrent of water come out for a full minute.
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Old 07-07-20, 01:02 PM
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I have a Bradford-White 75-gallon gas water heater that is from 1997, so 23 years old. I have a few questions on draining and flushing. I don't think it has been flushed for 10+ years.

1. I would like to drain/flush it but am concerned that given the age that might be risky. Could it expose some weak areas and potentially cause a leak? Is it best to let “sleeping dogs lie”? It works fine but maybe it is taking a lot of energy if there is a lot of sediment build up? I did check and water does come out freely from the drain if I open it up (it’s a brass fitting with a chrome handle).

2. If I do flush it, I could drain into a sump pit or run the hose up and out to the yard through a basement window. If I drain into the sump, would the sediment clog the sump pump? If I drain out the window will I need a pump – the window is about 8 feet above the level of the heater drain.

3. Should I proactively replace the heater given its age? It seems fine, but if it leaks would it be a burst and a flood in the basement? Or is it more likely to be a slow leak, which I could shut off and give me time to get a new one. I did ask Bradford, the guy on the phone said he had never seen a catastrophic leak, that it is always a slow leak. Of course, trying to replace a heater during an emergency is setting myself up for no time or leverage to get a good deal.

4. If I get a new one what is your opinion on a tankless one? I know they are more expensive to buy and install and the payback in reduced energy bills might be minimal. But I am more concerned about their reliability or other operational drawbacks.


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