Multispeed Heat Pump Rating Conditions for Low Speed

asked 2017-06-20 09:52:21 -0500

What performance inputs (e.g., capacity, COP) should be used for the low speed of a two-speed heat pump when cooling? The rating conditions specified in the I/O reference state 26.7 C dry-bulb/19.4 C wet-bulb indoor and 35 C dry-bulb/23.9 C wet-bulb for each speed. However, AHRI standard 210/240 only has a test at these conditions for the high speed (the A_2 test). The AHRI low speed test conditions are the same for the indoor but are either 27.8 C/18.3 C (test B_1) or 19.4 C/11.9 C (test F_1) for the outdoor. Note that there is a test B_2 for the high speed at the same conditions as B_1.

So, it seems my options are either to comply with the E+ specifications for the high speed and use results from the B_1 test for the low speed, or ignore the E+ specifications and stay consistent between the two tests and use results from B_2 and B_1. Thoughts?

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answered 2017-10-04 13:32:28 -0500

Matthew_Boyd
113 ●5

updated 2017-10-04 13:34:04 -0500

Answered by @rraustad via a help serve ticket:

"you can actually do either. The model expects that the data entered is at 80/67/95 as are the performance curves normalized to that data where the capacity and EIR curves are also 1 at 80/67/95. But if you choose a different rating point (loosely defined as 80/67/95)), and you normalize the performance curves to that point then the model should perform the same. Try it. The only note is that if the performance curves, and therefore the capacity and COP inputs, are not selected at the rating point, then warnings will likely be reported that the curve outputs at the rating point are not equal to 1.0 +- 10%. If this is done correctly at other than 80/67/95 then you can disregard the warnings."

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