Insights into NEEP min max
I’m trying to make sense of the great information I’ve gotten here (thanks Dana). I’m looking at the ASHP Specification Listing
https://neep.org/sites/default/files/ColdClimateAir-SourceHeatPumpSpecificationProductListing-Updated8.30.18.xlsx
Under multi split systems there is a Diakin listing that includes the following
Internal units (3) including CTXS07LVJU+FTXS09LVJU+FTXS09LVJU
Min Capacity 47 degrees = 7,720, Rated = 24,000, Max = 41,000
Does this imply that this set up would be able to modulate down to the 7,720 BTU? How might that be distributed?
Some other listings don’t indicate specific internal ductless units.
Some listings such as one with an LG LMU24CHV indicate a “Mixed Ducted and Non-ducted indoor units” but do not reference specific models.
I’m waffling with my configuration given the low load requirements between basement and first floor and the rooms.
Thanks
Carlo
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Replies
The min-capacity listed at any given temperature would indeed be it's minimum modulation level output at that temperature. Note that the minimum output is not the same across all temperatures. The NEEP spreadsheet lists minimums as well as maximums at a few different temperatures.
I'm not sure what is meant by "How might that be distributed?"
To list every possible combination with a multi-split such as the LG LMU24CHV would be cumbersome. Most vendors will have a submittal sheet listing the capacity for specific heads/cassettes when used with a multi-split, which is the nominal output at 47F. There is no min/max in those submittals, since when married to a multi-split comperssor the individual heads/cassettes don't modulate. At any temperature as long as the compressor still has the capacity to deliver the nominal heat to all active heads/cassettes on the system the zone will deliver approximately the 47F capacity number.
The user can bump the temperature and blower speeds, which will affect that a bit, but not by nearly as much as the full modulation of a single-zone minisplit. A zone will cycle quite a lot if the head/cassette is grossly oversized for the design loads taking a bit of an efficiency hit, but not nearly the hit that comes from cycling the compressor on /off rather than stepping up/down with the number & size of zones calling for heat/coolth.