When I was growing up, I learned so many DIY projects from my dad by observing him as he worked on home improvement projects! He was handy with his tools.
He went around the home, fixing structural and decor flaws all of the time.
He could not even help it when he was out going to see friends. His eye for perfection always observed something that needed fixing, especially Heating and A/C equipment. We all loved him for this! I watched him wire an electric gas furnace thermostat carefully and l learned how to do it. A while back, I saved a neighbor some bucks that he would have otherwise paid for his gas furnace thermostat wiring because the process is relatively easy. Begin by turning off the air handler or electrical circuit to the gas furnace. Note down the wire colors and what terminals each wire goes through. Better yet, take snapshots of everything you do while removing the old thermostat from your Heating and A/C system. My dad used the old-school method of labeling all the wires on the thermostat by marking each terminal and their corresponding wires. These notes or pictures will come in handy later while wiring your new thermostat. After that, disconnect the old thermostat and disconnect it. Put the new thermostat in place and begin re-wiring it to the terminal. Use your labeling notes or pictures to complete this process, then connect the wires one by one until you have reinstalled all of them and your new thermostat is installed. At this point, the job is done, but to confirm that it’s functioning correctly, turn on the electrical circuit and adjust the new thermostat to start the cooling or heating process. The thermostat should operate if the wires are attached accurately. If not, you might want to examine each terminal and the wire attached to it.