I am just purchasing the house, and the thermostat for A/C and heating is not there. I am just wondering if it will be possible for me to replace this myself. How do I know, what thermostat to buy? There is a wire hanging out from the wall where the thermostat should go. I believe that should help in identifying the thermostat I should go for.

Do we need to shutdown the entire electricity of the house to install the thermostat? Are there any electricity in the a/c-heating wires?

I am just wondering if it will be possible for me to replace this myself

Possibly



How do I know, what thermostat to buy?


You need to know what type of HVAC system you have.
Heat pump with or without electric heat
Gas furnace with or without A/C
Boiler or a combination of the above.



There is a wire hanging out from the wall where the thermostat should go. I believe that should help in identifying the thermostat I should go for.


I do not think so. Many times a thermostat wire is installed that has additional conductors.


Do we need to shutdown the entire electricity of the house to install the thermostat?

Just the power for the HVAC system.


Are there any electricity in the a/c-heating wires?

YES