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Bunslow t1_j19z1mz wrote

Reply to comment by GenericUsername2056 in Why do we use phase change refrigerants? by samskiter

right, but do residential heat pumps actually reach 300%, or do they only actually reach 250% or 200% or whatever and 300% is only possible with industrial heat pumps?

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SufferingIdiots t1_j1a1nrq wrote

This be will dependent on the temperature differential, the refrigerant and your specific equipment.

>At 8°C, the coefficient of performance (COP) of air-source heat pumps typically ranges from between 2.0 and 5.4. This means that, for units with a COP of 5, 5 kilowatt hours (kWh) of heat are transferred for every kWh of electricity supplied to the heat pump. As the outdoor air temperature drops, COPs are lower, as the heat pump must work across a greater temperature difference between the indoor and outdoor space. At –8°C, COPs can range from 1.1 to 3.7

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Bunslow t1_j1ajws0 wrote

hmm, so if it's -10C or -20C outside, and inside i want it at the usual 21 or 22C, then my cop might drop as low as 2? for residential purposes

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bluesam3 t1_j1b6s2k wrote

It will vary between models and setups, but yes, that seems like a reasonable number to expect, broadly speaking.

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bluesam3 t1_j1b6pb7 wrote

It's very climate-dependent - the colder the outside is, the less efficient air-source heat pumps tend to be (partly due to inherent reasons, and partly due to having to do work to defrost the outside unit) - if you're somewhere with relatively mild winters, COPs above 3.0 are very achievable with domestic units. If you live somewhere with extremely cold winters, it's much less achievable.

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