I'm replacing a toilet shut-off valve (clean water flowing into tank) on the first floor of my (100-year old) home. I'm reading that I need to shut off the water, then drain the lines, before making the repair. This toilet is on the 1st floor of a 2 story home, with the water heater in the basement. For example, here it says:
Shut off the water at the main shutoff valve. If you have a gas water heater, turn the knob to the 'pilot' position. Shut off the circuit breakers to an electric water heater. Then open a faucet on the lowest level of your house and another faucet on an upper level to drain the pipes. Then disconnect the supply tube from the shutoff valve. Replace the valve.
We have a gas water heater in the basement. My impression, though it may be wrong, is that if I shut off the water in the house, I also need to shut off the boiler such that it doesn't empty out and try to heat air, creating pressure and possibly an explosion. I could be wrong about this, and strangely enough I'm having trouble finding advice or readings.
My plan is to open the faucets on the floor below the floor with the toilet I'm changing in order to drain the system.
My question is: do I need to set the water heater to pilot, in order to avoid the dangerous scenario outlined above? Doing anything to our water heater makes me a bit nervous.
I've found a lot of advice on how to replace a toilet shut-off valve, but surprisingly little on this specific and incredibly common scenario.