How can there be a typical temperature drop?

This seems like a really strange question considering there is a typical indoor temperature but no typical outdoor temperature so how can the drop be typical? Up here in Canada the outdoor temperature in the summer can range from 50 to 100 degrees F on any given day so the drop would have to vary right? How do you get a typical drop?

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It’s not the temperature drop throughout the day it’s the temperature drop at that moment in time.

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Maybe the author meant to specify a difference in the indoor vs. outdoor coil temperature,
rather than implying ambient temperature.

Or supply vs. return temperature, for ducted systems. The 15 degrees is in the range of best efficiency.


I agree with Bryce. The question was worded incorrectly.

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@labstein Yeah, that kind of makes sense. It’s the expected affect on the environment at a moment in time regardless of the outdoor temperature. But that’s not what the questions says.

@bnesbitt That even makes more sense to me. The question doesn’t seem to be asking it that way though.

Yes, it is.
It is a bad question.
It is my recommendation that you just ignore this question and all attempts to answer it for you.

There is a big fight over this subject here:

A question on AC/Heatpump temperature differentials

Let the science of psycrometrics guide you through this mess… Or just give me a call and I will teach you.

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It’s difficult to ignore one of the possible questions on the exam I’m studying for. Since the questions on the exam could be different than the questions I’m studying, I have to aim for 100% just to get 80%.