water heater work

If you are working on the pipes above the hot water heater, is it necessary to totally shut the water heater off, or could you put it on vacation mode until you are done? Is there any damage that could be done if say only 3/4 of the water heater is full and the heater is on?

As long as the water is stil in the heater all you need to do is place it in the vacation mode like you thought. The only reason to drain any water would be because you had to solder a pipe with water in it or if the heat was causing the water to expand.

Turn off the water. Drain the pipes you’re working on. The pipes on top of the tank are threaded. If you drain any water out of the tank turn it off if electric or turn to pilot if gas.