I am getting ready to install a whole house humidifier. I was planning to tap the hot water line close to where it exits the hot water heater. I was going to use a Sharkbite Service Slip Tee. If I turn off the main supply, and drain the faucets, will I be able to do this safely? Should I also turn off the valve for the inlet line of the water heater? I have this fear of the water heater draining when I cut the line. I appreciate any input, and I apologize in advance for what is probably a stupid question.