| Kinda. First some terminology. HVAC mean Heating Ventilation and AC (i guess). It is the name for the general problem of dealing with the environment in the house. Second, about the Northern states. It really depends where you are and what your AC unit is. Some heat pumps don't have the capacity to heat a house in the North. If they're sized just right for cooling, they wont be powerful enough to heat your home [1] . As a result these units will start using resistive heating (emergency heat) which is the worst way to heat your home. Also, there is the edge case of extremely cold cities in the Midwest (Chicago is not cold enough). These cities have some days where the T can be -20F (about -30C). Not only does the COP start to plummet, the temperatures might be outside the operating range of the coolant. So you do have to do your homework before you install a unit. But I live in a Northern city now, with bad lows of 0F (-13C?) and the heat pumps work just fine. [1] In the South if you size your heat pump for cooling, you're sized ok for the heating. Even if you get a few days below freezing triggering the emergency heat, that's not a big problem. |