I'm looking for a house to buy in the South Carolina low country, where average lows in January get down to just under 40 deg F and highs in the summer get to just over 90 deg F. The houses in that area seem pretty evenly split between "gas and central A/C" and "heat pumps" for heating and cooling. I'm not sure which one is better.
I have read that "heat pumps operate optimally at approximately 45-50 degrees" (that source could be biased but I've seen similar numbers other places) - would it be right to conclude that heat pumps are more efficient than gas for my location? Or maybe a better question, how can I measure efficiency? Mostly I care about my utility bill, after all. Cost of gas and electricity obviously will change over time so I know I can't ask which is absolutely cheaper, but it seems that the most efficient of the two should "win."
Other factors I'm considering are long term cost and speed. I don't want to have to replace a major fixture every year. Is there a big difference in average "lifespans" between gas and heat pump? And I have heard stories that gas produces hotter air than heat pumps. Does it make temperature change noticeably faster as a result? In other words, if I'm cold, I don't want to wait four hours for the temperature to go up a degree.
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