mm wrote:
On Wed, 21 Mar 2007 19:35:21 GMT, Grandpa wrote:

Jeff Wisnia wrote:
Having just replaced the drain valve on our electric water heater, I
can safely say that you do not have to drain the tank to replace the
drain valve. Sure you drip a couple of cups of water, but advance
preparation controls that.

After getting advice from a supply house guy, I was able to change my
electric water heater heating element while only dripping a tablespoon
or two of water. I had a screw in element. A bolt-on might be a bit
slower to do.

The secret is to be sure that the cold
water inlet valve is closed and that all hot water faucets are also
closed.

Yes, I closed the main water supply to the house.

But what he told me to do was to OPEN the water faucet, only the
lowest one in the house I'm certain. And to let it stay open the
whole time and wait until the water stopped coming out of the faucet
before removing the element. I would think the procedure for the
drain valve would be the same. It only took 5 or 10 seconds for teh
water to stop dripping from the faucet, because of air pressure, etc.

(If it didnt' stop drippping at all, it would have likely meant that I
hadn't turned the water supply off sufficiently)

When you remove the old nylon valve a little bit of water
escapes, but without a way for air to get to the top of the tank,
there is nothing to displace the water and let it out. Just have
your nipple and ball valve pre-assembled and unscrew the old and
insert the new. Of course, you need to turn off your heat source
before starting this project. But I had it done in less than a
minute after preparation.

Absolutely. It only took me 3 to 4 seconds to get the element back in
and somewhat longer of course to screw the thing in to where it
stopped leaking. I hurried but don't remember how long that part
took. Actually I probably leaked some added water at that time, but
it was flowing very slowly when nothing was there, so I assume it was
even slower when most of the hole was plugged.

WE NEED PEOPLE HERE TO RESOLVE WHETHER ALL THE HOT WATER FAUCETS
SHOULD BE CLOSED, AS YOU SAY, OR WHETHER THE LOWEST ONE IN THE HOUSE
SHOULD BE WIDE OPEN, AS I SAY.

Did you open the hot or cold valve? If it was the lowest cold valve,
I can understand that - check to make sure the water is off and
relieve the residual pipe pressure from the tank.

Common sense tells me that if I provide an air path to the top of
the tank from an open hot water faucet, then I can empty that water
tank quickly. Try it yourself with a soda straw in a tall glass of
water. Put the straw in the water, put your finger over the top of
the straw and remove it from the glass. The straw will be full of
water, except for a little bit that the weight of the water will
pull down before the vacuum created below your finger stops it. Pull
off your finger and the straw will empty out.

Still don't believe me? Try he
http://www.maytagwaterheaters.com/ideas/mainttips.html
Look at item 3 under "How To Flush & Drain Your Water Heater"
Now stop yelling.
--
Grandpa