Hot Water tap runs dry

[koreiryyu]

Edit: I'd like to say I was wrong. Leaving the taps closed for awhile isn't building pressure. If both taps stay off for awhile, the hot water still runs dry. I'm thinking there's something wrong with the cold water intake valve.. suppose it's not actually opening when I turn it?
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I've searched the forum (I try to do that before making duplicate posts) but the posts I've seen talk about an air lock, the question I want answered is different.

I initially closed the cold water intake to my water heater because I only needed to replace a tub valve stem to the hot water, but then I was asked to change both so I turned off the main supply.

I did the job, turned the water to the main back on, then the cold water intake to the hot water heater... And my hot water wouldn't turn on.

So after doing some Googling I kept finding posts about relieving an airlock, and then I noticed my hot water would turn on.. but after 20 seconds it would run dry. But would all the hot and cold water drain from the water heater in 20 minutes, enough to cause this problem?

 

[phishfood]

Is the valve on the water heater a quarter turn type, or does it have a wheel handle that you have to turn multiple times to go from "full on" to " full off"?

 

[Mr_David]

Gate Valve. Often the stem breaks when you close an old gate valve.

 

[phishfood]

^Where I was going.

 

[koreiryyu]

Gate Valve. Often the stem breaks when you close an old gate valve.

Yep. It's a broken stem. No idea how to replace one of these.

 

[wyrickmech]

Yep. It's a broken stem. No idea how to replace one of these.

Cut the valve out and replace. Or unscrew the bonnet and remove the gate for a quick temp fix.

 

[phishfood]

Cut the valve out and replace. Or unscrew the bonnet and remove the gate for a quick temp fix.

Welcome, wyrickmech!