Strange water problem when trying to drain hot water tank

[ZK2]

Okay, I have a bad lower heating element and I thought I would change it myself. Sounds easy, but it has been anything but. I have a Bradford White water heater. So, I shut off the electric and then shut off valve on the incoming cold water line. No hot water comes out like it shouldn't. Then I attach a hose to the drain and open the drain.

Unfortunately, very little water actually comes out. I take the hose off and still very little water comes out. Only enough to fill a small pan every so often. Now comes the weird part.

Just for giggles I turn the cold water tap on and water gushes out the hot water tank drain. Turn the cold water off and it is back to a trickle. Oh one other thing, when I turn the cold water on and open the hot water taps on my other sinks cold water comes out there too and when I shut the colder off they all stop.

So, how can cold water come out of the hot water tank drain and also out of the hot water faucets when the cold water input to the hot water tank is turned off. This is driving me bugs. I am just about to call a plumber, but I thought I would ask someone here first just to see if anyone has ever seen this.

:confused

 

[Matt30]

Your tank is air locking with all the taps closed. Turn cold water off to the tank, and open up a hot tap somewhere above it. It will still drain slow, but it will eventually.

 

[journeyman]

or just disconnect the hot supply line to heater and let air in that way it is faster. you may have to change supply line though

 

[Mr_David]

Safer to drain a tank to replace an element but I never have. A couple towels on the floor and unscrew the element. Just make sure you relieve the pressure by opening a faucet , then close the faucet. Just to make sure you don't have something leaking by that re-pressurizes the tank, open the faucet again. Close it again. As long as it is air locked, a minimum amount of water will come out of the element hole. You will have to be quick and ready with the new one. Make sure you have a new o-ring/gasket on the new one ready to go. .. OR just Drain it.

 

[frodo]

the reason the tank does not drain is no vent.

simple tutorial . put a straw in a glass of water. put your finger over the end of straw
pick up straw. no vent, will not drain, straw stays full of water
take your finger off the straw. vent, drains