In general, most HVAC systems will last 15 to 25 years, but depending on the type of system and other contributing factors, that estimate can be highly variable. Even with HVAC maintenance and regular repairs, eventually, even the best boilers, furnaces, heat pumps, and air conditioners today will run their course.

Anyone who's opened an eye-popping energy bill in the middle of winter or one for air conditioning in the summer has probably wondered which system costs more to operate. According to analyses, it's no comparison: heating your home requires four times more energy in the US than cooling your home.

The systems operate by either absorbing heat inside the building and transferring it outside to cool the building, or vice versa, absorbing heat from outside air and bringing it inside.