How Do I Drain/Flush Water Heater Properly??


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Old 10-29-13, 11:46 AM
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Question How Do I Drain/Flush Water Heater Properly??

AO Smith ProMax
model# XCV 40 2000

I did the following steps, but all i get is a few drips of water coming out from the drain valve. There is a main water shut off valve in the back, but on the top of the tank I noticed that there are no shut off valves. Is that the reason why i only get a few drips of water? Please let me know if you have suggestions:
  1. turn thermostat to pilot setting
  2. turn off water supply in back,
  3. turn on hot water faucet in home to make sure there isn't a vacuum in lines (leave it open),
  4. open drain valve on bottom of tank and do not use pressure relief valve on top,
 
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Old 10-29-13, 11:55 AM
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Welcome to the forums.

I don't do most of that, just step 4. How long has it been since the tank was flushed? Could be that it was too long and the sediment buildup has clogged the opening - we took one out of one of our units several years ago and cut it apart (we were curious) and found it to be half filled with sediment.
 
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Old 10-29-13, 12:21 PM
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I agree no need to do any of that other stuff.
May have to open the drain and stick a metal coat hanger in the hole to get it running.
Some just can not be drain because there's just to much trash in it.
 
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Old 10-29-13, 12:32 PM
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May have to open the drain and stick a metal coat hanger in the hole to get it running.
I think it may be difficult to snake a wire through the drain valve, and if you do, you may booger the valve internals. I would cool down the heater, isolate the water supply, and remove the drain valve - then go at it with the coat hanger. Once you get the water flowing, crack open the supply valve and begin to flush with the drain valve still removed.
 
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Old 10-29-13, 04:36 PM
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I hook up a hose to the drain fitting and open the valve. The water pressure helps force out debris and since the heater remains filled with water there is not need to turn it off or change the thermostat setting.

If the draining clogs I go to plan B. A shallow bucket or tray that will get under the drain fitting. I cover the drain and catch tray with a rag to contain splashing. Open the valve and shove a heavy/large plastic wire into the outlet with my hands under the rag. Poking and fishing around usually clears the blockage and water, chunks and schmutz spew out. If the heater has not been regularly drained this may need to be repeated many times.
 
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Old 10-29-13, 05:00 PM
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You try and remove that valve when the tank is still full of water one of two things is going to happen.
The valves going to snap off or the valve goes off and waters going to come gushing out along with the trash in the tank which is going to get into the pipe threads making it impossible to get a new valve back on or it's going to at least leak.
 
 

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