Thank you, this helps tremendously!
Next week I'll be traveling but it's not meant to get below 48F, so I'll just shut the heat off completely.
In December, I'll be out of the country for a few weeks so I'll follow these tips. I'm not sure if I'm able to shut my water off at the main - I attempted to do it myself a few years ago when I had a water leak, but the plumber had to do it with a special tool. Maybe it's worth it to see if I can buy one of those tools somewhere.