Mystery draining the water heater


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Old 10-03-19, 11:52 AM
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Mystery draining the water heater

I was going to drain my electric water heater to get the crud out of the bottom. I followed these instructions, which I had written & saved last time, based on research.

1. Close the inlet valve at the top of the heater

2. Attach a hose to the drain and run it out the door

3. Open the drain valve

4. Open a hot faucet to let air into the water heater as it drains.

However, when I opened the drain valve, nothing came out!

Experimentally I tried opening the cold water supply, and that made water come out the hose—so the hose is not clogged.

Then, just for the heck of it, I closed the cold water supply to the water heater, and opened a cold water tap in the bathroom. For some reason, water then started coming out the drain hose from the water heater! This makes no sense to me. Can anyone explain this?
 

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10-03-19, 12:22 PM
Pilot Dane
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I never turn off the water as the pressure helps the cleaning process. Just attach your hose to the drain fitting and open the valve. Plain and simple.

If you have not drained the heater regularly then the drain valve is likely clogged. One option is to turn off the water, drain the pressure from the system. Then replace the drain valve that came with the heater with a 1/4 turn ball valve which is less likely to clog. You can also shove zip ties or a piece of wire up into the clogged valve to break up the clog. Just be ready for a spray of nasty, possibly snotty, chunky water heater scum.
 
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Old 10-03-19, 12:22 PM
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I never turn off the water as the pressure helps the cleaning process. Just attach your hose to the drain fitting and open the valve. Plain and simple.

If you have not drained the heater regularly then the drain valve is likely clogged. One option is to turn off the water, drain the pressure from the system. Then replace the drain valve that came with the heater with a 1/4 turn ball valve which is less likely to clog. You can also shove zip ties or a piece of wire up into the clogged valve to break up the clog. Just be ready for a spray of nasty, possibly snotty, chunky water heater scum.
 
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Old 10-03-19, 01:52 PM
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So you just open the drain until the water coming out is clear? I thought you had to drain the whole thing to get all the crud out.

My drain valve must not be clogged, since water comes out the hose when I open the cold water supply to the water heater.

I still don't understand why nothing comes out the way I did it...
 
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Old 10-03-19, 02:42 PM
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So you just open the drain until the water coming out is clear?

Yes, at least that is all I do.
 
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Old 10-03-19, 04:50 PM
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The gunk you are removing is only at the bottom of the tank. After all, when you use hot water in the house you are getting nice clear water so you gotta know that most of the water in the tank is clear and doesn't need to be dumped.
 
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Old 10-04-19, 04:38 AM
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To answer your question...You're pulling a vacuum. The hot water valve opening is to far removed from the system and not good enough to allow the air to escape. That's why you open a cold water valve.
 
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Old 10-04-19, 07:21 AM
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Thanks to All!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
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Old 10-06-19, 02:56 PM
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>>> 1. Close the inlet valve ...

You left out the most important step!

1. Turn off the water heater heat!

Renumber the remaining steps with 2, 3, etc. respectively.

If you accidentally drain too much water and the heating elements kick on the water heater will be damaged.

If a gas water heater is drained too low then it, too, will be damaged if it kicks on.

Open a hot faucet (single handle shower or sink faucet set to full hot) upstairs and see water gushing out for a full minute before turning the water heater heat back on.

Alternate between draining (cold inlet above water heater shut off) and flushing (cold water inlet left on). If you got a lot of sediment out, do the next draining or flushing, whichever comes next in turn, no more than a month later which gives the remaining sediment a chance to redistribute itself at the bottom of the tank and more will come out the next time.

Some water heaters equipped with heat trap nipples (hard to distinguish from ordinary inlet and outlet nipples) will drain sluggishly or maybe not at all although flushing will go okay.
 
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