Hi there ! The hot water valve to the sink leaks a bit and I want to change it before I start painting. I know I have to close the main valve but what do I do with the hot water tank ? Do I shut it off or empty it and if so how I do I go about filling it again ? :confused:
Thanks to whoever answers my question I appreciate it.

Describe the faucet. One handle, two knobs or a separate valve for hot and cold.
Or would it be the hot water angle stop in the cabinet?
To shut the hot water off to the faucet you can do it in any one of three places.
1) the hot water angle stop in the cabinet
2) the cold water supply to the hot water tank, **or**
3) Close the house shut of shutting down the entire system.
Good luck, Tom

After you shut off the water, and I suggest that you turn off both the hot and cold water especially if it is a single handle faucet on the bathroom sink. After you are finished you will not have to do anything to the water heater, it will remain full of water and it will remain lighted.

When you open up a hot water faucet for the first time after the repair you might get a rush of air, this is normal and should clear up immediately.

OK, y $.02.

Turn off the gas or electric to the hot water. For gas heaters turning it to Pilot or Vacation is sufficient.

Turn off the cold water to the heater.

Open the hot tap. Particularly the lowest and highest one in the system.

Drain about a bucket (1 gallon or so) of water from the hot water heater.

Turn off the cold under the sink.

Make SURE that no water comes out the tap your trying to change the shutoff valve to.

If it does, turn off the cold water main. Make sure the water is off before beginning work.

Please tell us about this hot water valve is this the angle valve under the sink or this is your faucet hot side leaking, it may be an easy fix if it is the angle valve under the sink, if it leaking from the packing nut just tighten the nut a little and the leak will stop or you can replace the rings, see the image below, for this you would not need to turn off the gas or drain the water heater just close the main S/O valve and open the faucet to drain the water, Thanks.

John