This is a bit embarrassing but I'm unable to figure out how my house is actually heated.
I have some vents in the wall (just above the baseboard), which blow out hot air and are controlled by one thermostat in each room. The same thermostat + vent is in the living room.
Plus, the living room also has a gas fireplace.
Now, I've turned off all the thermostats + have put off the pilot light in the fireplace, but when I place my hands near the wall vents, I still feel heat. Not sure how to turn it off.
Please help me figure out the mechanism of heating and how to turn it off. Here are photos of the water heater in the basement, my only guess is that this has something to do with space heating too, but am not sure.
Pictures are here: https://imgur.com/a/XX1rvA7