If you understand basic electrical systems, installing a programmable thermostat can be a do-it-yourself job, done to the manufacturer's specifications. If you're unsure about your electrical knowledge or uncomfortable with the idea of working with electricity, definitely hire someone qualified to do the job for you. Once it's installed, though, and you have a heating system of some sort (furnace, boiler, heat pump, etc.), a correctly operating thermostat should give you some control—not to mention the potential for energy savings and, in the end, comfort in your living space.