I always shut off my water main when we gone even just for the weekend. Ball valve is right in the attached garage so I’m usually walking within a few feet of it anyway as I’m getting in the car or truck.
My hot water baseboard heat also has a water feed to it with an auto fill valve. However, it has a 5 gallon water/air expansion tank which keeps 2 or 3 gallons under 40 psi air pressure right at the boiler. I have a separate ball valve on the pipe leading to the boiler which I also shut, so no loss of water to boiler.
It Barely takes any water anyway. One winter I left the water feed off for over a month, and upon opening it, the auto fill valve opened for 2 seconds and then was full and off. Maybe a pint of water.
