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I’ve been independently interested in heat pumps because I need to replace my old end-of-life system and I’ve been interested if a modern cold-weather mini spli

I’ve been independently interested in heat pumps because I need to replace my old end-of-life system and I’ve been interested if a modern cold-weather mini split system is a better investment. There’s lots of conflicting info I’ve found on if heat pumps perform in freezing weather and at what kind of efficiency. I’m sure there’s others in my position.

fullstop 4y ago
Where do you live geographically? I'm in eastern Pennsylvania and have lived with a heat pump for 20+ years.
- helen___keller 4y ago
  Massachusetts
  - fullstop 4y ago
    A bit colder, on average, than where I live. You might want to look at ground-loop HPs or ccASHPs.
sbradford26 4y ago
So largely I think the confusion stems from there being two major different "types" of heat pumps and they perform very differently. The first is your conventional type system, this is usually what AC units are in the US. They run at maybe 1 or 2 speeds. These type of heat pumps are common in the southern parts of the US but also will be found paired with a gas furnace in the northern US. Since they don't adjust their output dynamically they tend to start losing capacity/efficiency significantly around 25-30F. The second is an inverter driven heat pump. You usually find these in mini splits but they can also be found in a standard air handler form factor that would replace a furnace. The inverter allows the compressor to adjust based on demand and exterior temperature to maximize efficiency. This allow these units to operate efficiently down to -13F depending on the unit. Now there will still be some capacity loss at those temps so during the design of the system this has to be taken into account. For detailed information on the efficiency of heat pumps I would check out NEEPs website. It is a great resource, it will show you capacity and efficiency (COP) of tons of different units across their operating temperatures. https://ashp.neep.org/ https://ashp.neep.org/
kwhitefoot 4y ago
Heat pumps sold in Norway are claimed to work down to -30°C. See, for instance, the Samsung Nordic Extreme: https://www.elkjop.no/product/hjem-rengjoring-og-kjokkenutstyr/inneklima-og-varme/oppvarming/varmepumpe/samsung-nordic-extreme-09-varmepumpe-ar09bxfydwkee/522095?service=INSTHEATPUMPB#specifications https://www.elkjop.no/product/hjem-rengjoring-og-kjokkenutst... I don't know what the coefficient of performance is at that temperature though.
rayiner 4y ago
I’ve got a mid-range Amana heat pump and even that has a COP of 2.1 (2 watts of heating per watt used) down to 0F. Heat pumps require different system design than a traditional setup, where the cooling load is usually the driving force. You might need a bigger heat pump to handle the heating load in very cold weather accounting for the efficiency loss.

fullstop 4y ago

Where do you live geographically? I'm in eastern Pennsylvania and have lived with a heat pump for 20+ years.

helen___keller 4y ago
Massachusetts
- fullstop 4y ago
  A bit colder, on average, than where I live. You might want to look at ground-loop HPs or ccASHPs.

sbradford26 4y ago

So largely I think the confusion stems from there being two major different "types" of heat pumps and they perform very differently. The first is your conventional type system, this is usually what AC units are in the US. They run at maybe 1 or 2 speeds. These type of heat pumps are common in the southern parts of the US but also will be found paired with a gas furnace in the northern US. Since they don't adjust their output dynamically they tend to start losing capacity/efficiency significantly around 25-30F. The second is an inverter driven heat pump. You usually find these in mini splits but they can also be found in a standard air handler form factor that would replace a furnace. The inverter allows the compressor to adjust based on demand and exterior temperature to maximize efficiency. This allow these units to operate efficiently down to -13F depending on the unit. Now there will still be some capacity loss at those temps so during the design of the system this has to be taken into account. For detailed information on the efficiency of heat pumps I would check out NEEPs website. It is a great resource, it will show you capacity and efficiency (COP) of tons of different units across their operating temperatures. https://ashp.neep.org/ https://ashp.neep.org/

kwhitefoot 4y ago

Heat pumps sold in Norway are claimed to work down to -30°C. See, for instance, the Samsung Nordic Extreme: https://www.elkjop.no/product/hjem-rengjoring-og-kjokkenutstyr/inneklima-og-varme/oppvarming/varmepumpe/samsung-nordic-extreme-09-varmepumpe-ar09bxfydwkee/522095?service=INSTHEATPUMPB#specifications https://www.elkjop.no/product/hjem-rengjoring-og-kjokkenutst... I don't know what the coefficient of performance is at that temperature though.

rayiner 4y ago

I’ve got a mid-range Amana heat pump and even that has a COP of 2.1 (2 watts of heating per watt used) down to 0F. Heat pumps require different system design than a traditional setup, where the cooling load is usually the driving force. You might need a bigger heat pump to handle the heating load in very cold weather accounting for the efficiency loss.