If you shut off the water to the whole house at the main valve, and leave the hot water heater on, should you open both the hot and cold water faucets? Or just the cold? The heat is on to about 60 degrees, my husband wants to open the hot water faucet, but I think it would drain the water out of the water heater. Who is right? We will be away for 3 months, I will leave the cabinet doors open under the sinks. Thank you.

Sorry, he is. Will not drain the heater. No reason to drain it unless you are afraid of a tank leak. Set the HW heater to "vacation" setting or very low if electric. You can leave the faucets open or closed.

Not sure where you live but 60 degrees is way more heat than you would need tp protect your home from freezing. No need to drain anything if the main is closed. Where do you live and do you have a router in your home?

Some of what you do depends also on how old your house is, with many old houses having no insulation and with pipes running through very cold spaces and outer walls.

Another concern is power outages and furnace or boiler not working. There are little thermostats that can call a neighbor, plumber, heating co. or you if temp goes below a set degree.