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In common usage, the term "A/C" refers to a kind of heat pump that only does cold, whereas "heat pump" means one that does both hot and cold. A refrigerator al

In common usage, the term "A/C" refers to a kind of heat pump that only does cold, whereas "heat pump" means one that does both hot and cold. A refrigerator also has a heat pump, but we just call them refrigerators. Part of the problem is in temperate climates, if you have "A/C" you probably _also_ have a furnace. They might run on different fuels (electric vs. natural gas) so it makes it harder to get a ballpark estimate for the overall efficiency.

tspike 3y ago
I see. So this comes from a temperate climate perspective, where it's historically been the case that everyone _needs_ heat but cooling is an optional luxury. This perspective would seem to need revisiting with a changing climate and in a global context.
voisin 3y ago
Why does anyone make A/C’s rather than just make Heat Pumps that run in both directions? Is there a cost difference?
- hoosieree 3y ago
  Heat pumps are about 1.3x up front cost, but 0.75x over the life of the unit. New construction therefore tends to prefer a/c, but some federal and state subsidies are kicking in soon to sweeten the deal. In really cold climates (e.g. Minneapolis, Montreal) heat pumps often also need a supplemental furnace or fireplace because the heat differential inside vs. outside exceeds what the pump can handle. Depending on your fuel source, you still come out ahead, but not as much. I should note that I'm not an expert by any means; my brother in law works in this field and he gave me a crash course a couple weeks ago. So I probably feel like I know it better than I actually do. [1]: https://carbonswitch.com/heat-pump-vs-ac/ https://carbonswitch.com/heat-pump-vs-ac/
  - voisin 3y ago
    I am aware there is a cost premium up front but I am wondering if this is just due to the production scale of AC units versus heat pumps or if there is something fundamentally, non-trivially more expensive?
dragonwriter 3y ago
> In common usage, the term "A/C" refers to a kind of heat pump that only does cold, whereas "heat pump" means one that does both hot and cold. Does it though? That seems to be some kind of subcultural jargon that matches neither common (which uses central heating and air conditioning for any central system that cools with a heat pump regardless of how it heats) nor industry usage. (My fairly nee system, marketed as A/C, has both a two-way heat pump and a gas furnace to back up the heat punp for heating.)

tspike 3y ago

I see. So this comes from a temperate climate perspective, where it's historically been the case that everyone _needs_ heat but cooling is an optional luxury. This perspective would seem to need revisiting with a changing climate and in a global context.

voisin 3y ago

Why does anyone make A/C’s rather than just make Heat Pumps that run in both directions? Is there a cost difference?

hoosieree 3y ago
Heat pumps are about 1.3x up front cost, but 0.75x over the life of the unit. New construction therefore tends to prefer a/c, but some federal and state subsidies are kicking in soon to sweeten the deal. In really cold climates (e.g. Minneapolis, Montreal) heat pumps often also need a supplemental furnace or fireplace because the heat differential inside vs. outside exceeds what the pump can handle. Depending on your fuel source, you still come out ahead, but not as much. I should note that I'm not an expert by any means; my brother in law works in this field and he gave me a crash course a couple weeks ago. So I probably feel like I know it better than I actually do. [1]: https://carbonswitch.com/heat-pump-vs-ac/ https://carbonswitch.com/heat-pump-vs-ac/
- voisin 3y ago
  I am aware there is a cost premium up front but I am wondering if this is just due to the production scale of AC units versus heat pumps or if there is something fundamentally, non-trivially more expensive?

dragonwriter 3y ago

> In common usage, the term "A/C" refers to a kind of heat pump that only does cold, whereas "heat pump" means one that does both hot and cold. Does it though? That seems to be some kind of subcultural jargon that matches neither common (which uses central heating and air conditioning for any central system that cools with a heat pump regardless of how it heats) nor industry usage. (My fairly nee system, marketed as A/C, has both a two-way heat pump and a gas furnace to back up the heat punp for heating.)