Final answer:
Closing registers in uninhabited rooms can save energy, but may lead to a less efficient heating system, duct leaks, increased furnace wear, and potentially cause issues such as frozen pipes or mold due to uneven heating and cooling.
Step-by-step explanation:
If you close the registers in uninhabited rooms while in heating mode, the immediate effect is that those rooms will receive less heat from the heating system. This might seem like an efficient way to save on energy consumption because you are not heating unused spaces. However, this can have unintended consequences. Closing registers can disrupt the balance of the heating system and potentially cause it to work less efficiently. For instance, it may lead to increased pressure in the ducts, causing leaks where heated air escapes, or it could force the furnace to work harder to distribute air throughout the home, leading to increased wear and tear.
Additionally, if the house is not properly insulated, the cooler temperature in the closed-off rooms can affect adjacent areas, potentially making the heating system work harder to maintain the desired temperature in the occupied parts of the house. Furthermore, if temperatures drop significantly in the uninhabited rooms, it can lead to issues like frozen pipes or increased humidity and mold growth, which can damage the structure and reduce indoor air quality.