I've had my electric water heater for 5-6 years and decided to drain it for the first time (yeah, I know). Following directions on a how-to site, I powered off, closed the cold water feed valve, opened the hot water faucet on the nearby slop sink, and opened the drain valve. The heater is in the garage at ground level, and I ran a hose to the driveway. I expected 50 gallons of water to drain kind of forcefully, but it came out in a trickle with the drain valve wide open. I momentarily opened the cold water feed and the water rushed out much faster, and seemed to run clear. Do I have a problem, or should I just have been more patient in letting it drain?
The primary purpose of this maintenance procedure is to get rid of sludge that may accumulate at the bottom of the tank. Therefore, it's not necessary to completely drain the tank, but to flush out what's on the bottom. So you can leave the supply water on and open the drain valve for a few minutes. Also, many heaters are equipped with cheap one-time use drain valves that may not have a real wide opening. Consider replacing it with a brass boiler drain valve.
ACTUALLY, the proper procedure IS to drain it completly, then 'blast' the bottom by opening the cold inlet and shutting it several times. Merely opening the drain valve will not stir the bottom sufficiently to remove deposits. Of course, if you're going to wait 5 years to do it, (instead of
3 or 4 times a year), then it's a futile effort anyway.
s
Your water utility pressurizes the water supply with water pumps. When you drain, you only have gravity working for you. Gravity is slower than pressurized water from the street.
If you live in two story house, or your Water Heater in in the basement, open up a faucet at the highest point possible. Myself, I like upstairs bathroom tub faucets. Others have their own favorites.
Don't ask how I know this, but be sure your tank is full of water, and I mean completely full of water before restoring electric power to the heating elements. Otherwise they will burn out if not completely covered with water.
Most cities use water towers to provide the pressure and a piddly-assed pump to fill it. By so doing, the city can pump 24/7 even though the demand at night is negligible. The tower acts as a big buffer.
The height of the tower determines the water pressure, every PSI requires
2.34 feet of elevation. Therefore, most towers are in the 100-140 foot range (43-60 psi).
Bob, I went for the lazy man's drain valve - 1/4 turn! It may not be the most correct but it sure is handy. I also replaced the pipe back into the tank with a 6" brass (important to prevent corrosion) pipe nipple and then put the 1/4 turn valve on the end. I only purge it twice a year and plan it around a return after being away for a long weekend. I turn off the electricity to the tank so that it isn't regularly reheating. Then, I do the drain and re-fill when we get home. It generally takes about 1.5 hours to get this done. I have entertained the thought of adding air pressure (very low) to the lines to hasten the rate of drainage.
My previous water heater was a sears, with the Roto-Swirl intake tube, or whatever they call it. The intake tube extends to near the bottom of the tank then turns into a semi-circular tube closer to the perimeter of the tank than to the center, and the tubes outlet points sideways. They say it will lift up the sediment at the bottom so that it doesn't mount up. I have screens in almost all my faucets including the clothes washer intake and they never need cleaning. I almost never use the laundry sink (which has no screen) and I never find sediment in the bath tub water. Plus I don't see how much swirling will really take place when the intake water is going into a full water tank. Some, but not enough to lift up the sediment until the sediment is close to the intake pipe, I think.
FWIW, my water heater was about 8 years old, never been drained. I live in Baltimore and my water comes from Liberty reservoir, or maybe Prettyboy Reservoir or the other one. When I cut the thing open there were only about 2 or 3 tablespoons of mostly white grains in the bottom, maybe a quarter inch deep in the semi-spherical bottom of the water heater.
I'm sure others have more sediment, but in my case, at the rate it was going it would take 100 or 200 years at least before the deposits in the bottom would have reached the electric heating element. And the drain was also several inches above the level of sediment, so even had a I drained the tank, no sediment would have run out with normal draining. Even if the sediment level was a couple inches, even the blasting that S Barker recommends would have only gotten a little at a time. I would have had to blast for hours to get even a couple cups of sediment out of the thing.
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