Water shutoff valve won't turn off all the way

[ctown]

I'm trying to replace a faucet in a bathroom sink, and the hot water shutoff valve under the sink won't turn off the water all the way -- it just reduces the flow. I was able to turn off the cold water all the way, but it appears something is wrong with the hot water shutoff valve. Any suggestions?

[LazyPup]

That is a common problem with the angle stop valves as they age.

Since this is on a hot water line you can turn the water off at the Cold water supply valve to the water heater.

When working on a cold water line, or when both the angle stop and water heater supply valve won't hold you can turn all the water pressure off at the house "Main Water Shutoff" where the water line enters the house.

[ctown]

If I turn off the water supply to the hot water heater, will that require me to drain the entire water heater in order to have the water not flow out from the hot water faucet when I disconnect it?

[LazyPup]

No,,the water heater is simply a holding tank with a heating element underneath or inside. The flow of water coming out of the water heater is propelled by the pressure of the water entering the heater. If you turn the water heater supply valve off there will be no pressure going into the tank, therefore there will be no flow coming out and the water will just remain in the tank.

[mrcaptainbob]

There may be a bit of residual pressure in the hot water system after shutting off the cold water inlet to the heater tank. Crack a hot water faucet any where in the system to relieve that pressure. Make sure to shut that faucet off before you open the angle stop valve.