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Water Heater Won't Drain

Posted by wxman5 (My Page) on
Mon, Sep 5, 11 at 16:33

I'm replacing my 20-year-old gas water heater with a new one, but can't seem to get the old unit to drain. I shut off the gas and water supplies and attached a hose to the drain valve, turned on a few hot water taps in the house to break any vacuum, but all I get is about 5 gallons of clear water (no rust or sediment) that drains out. I can turn the water supply back on with the drain-valve open and water flows out with good pressure. In short, my water heater is acting like it only has a 5 gallon capacity. (Its a 50-gallon unit.) Any suggestions?

Follow-Up Postings:

RE: Water Heater Won't Drain

Open the temperature and pressure relief valve on the side near the top of the heater. Or it may be on the top.

RE: Water Heater Won't Drain

If you are using the typical plastic outlet on the tank they do not have much clearance.

Even a small amount of scale will clog the drain.

RE: Water Heater Won't Drain

Sounds to me like there's enough crud in there to block the passage once it starts flowing. Suggest the "coat hanger trick" which I mean running a stiff wire up through the open valve and wiggle it around to dislodge the obstructions. If there's that much crud in there, I suspect you may have to stay right there and keep wiggling the wire while it dribbles out annoyingly slowly.

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