It is relatively new, installed in 2006 or so, alongside a condensing natural gas furnace. The furnace provides heat, the AC provides cool. It’s working okay for now, when it’s time to replace it I’ll replace it with a heat pump system and retain the furnace for emergency and defrost.
Unless it gets very cold, probably no need to keep it. Had mine removed and I live in the UK. Not sure if there is anywhere that needs AC in summer and gets too cold for a heat pump in winter.
Emergency heat is a legal requirement. A heat pump system without a source of emergency heat does not meet the North Carolina residential building code. That law was written back when AC was newfangled and untrusted, and Raleigh (and many other state capitols) didn’t want families freezing to death because a compressor motor failed.
American central HVAC systems are modular by nature, a heat pump system is designed to rely on the emergency heat system for defrost heat. Auto-defrost is accomplished by overriding the thermostat and commanding Emergency Heat ON, reversing valve to AC, compressor ON, fan ON. The ensuing sparring match between the heater and air conditioner pretty effectively defrosts the outdoor unit. And in the United States at least, by far the world’s largest producer of natural gas, it’s considerably less expensive to do that under methane power than electricity.
Defrost is a critical feature in my climate; winter hovers around freezing, often climbing to 1 or 2C during the day and dipping to -3 or -4C at night, and the relative humidity is ALWAYS high. Perfect icing conditions for a heat pump.
Surely a heat pump can fail just as easily as a boiler? Log burner or even a biofuel fire kinda thing would be far more suitable as an actual emergency backup.
Not all are reversible, and given they said when it goes I would assume it is an older one that can’t do heating.
It is relatively new, installed in 2006 or so, alongside a condensing natural gas furnace. The furnace provides heat, the AC provides cool. It’s working okay for now, when it’s time to replace it I’ll replace it with a heat pump system and retain the furnace for emergency and defrost.
Unless it gets very cold, probably no need to keep it. Had mine removed and I live in the UK. Not sure if there is anywhere that needs AC in summer and gets too cold for a heat pump in winter.
Not an option. Two reasons:
Emergency heat is a legal requirement. A heat pump system without a source of emergency heat does not meet the North Carolina residential building code. That law was written back when AC was newfangled and untrusted, and Raleigh (and many other state capitols) didn’t want families freezing to death because a compressor motor failed.
American central HVAC systems are modular by nature, a heat pump system is designed to rely on the emergency heat system for defrost heat. Auto-defrost is accomplished by overriding the thermostat and commanding Emergency Heat ON, reversing valve to AC, compressor ON, fan ON. The ensuing sparring match between the heater and air conditioner pretty effectively defrosts the outdoor unit. And in the United States at least, by far the world’s largest producer of natural gas, it’s considerably less expensive to do that under methane power than electricity.
Defrost is a critical feature in my climate; winter hovers around freezing, often climbing to 1 or 2C during the day and dipping to -3 or -4C at night, and the relative humidity is ALWAYS high. Perfect icing conditions for a heat pump.
Isn’t that a requirement only applicable to health facilities, and one that you can also skip if you have two separate energy sources?
Surely a heat pump can fail just as easily as a boiler? Log burner or even a biofuel fire kinda thing would be far more suitable as an actual emergency backup.
I lived in an NC apartment complex. When the power went out, we froze. There was no emergency heat.