MrCool Olympus E Star 4th Gen 24,000 BTU

Model O-ES-24-HP-C-230C-O1 · O-24-HP-WMAH-230C-O

SCORE7.4 / 10

Big output in the cold (24,200 BTU/h at 5°F), but it doesn't turn down any lower than the 18k on a mild day, so size it from a load calculation.

Specs

Spec	MrCool Olympus E Star 4th Gen 24,000 BTU
Nominal size	24,000 BTU
Voltage	230V
Rated heat at 47°F	29,000 BTU/h
Heat at 17°F	22,200 BTU/h
Heat at 5°F	24,200 BTU/h
Lowest heating temp	-22°F
Max heat at lowest temp	11,900 BTU/h
SEER2	21
HSPF2 (Region IV)	13.5
Install type	Flare
Warranty covers owner install	No
Warranty, parts	5 yr
Warranty, compressor	7 yr
ENERGY STAR Cold Climate	Yes
ENERGY STAR	Yes
Refrigerant	R-454B
Heat at 17°F per MrCool submittal	21,000 BTU/h (NEEP lists more)
Pre-charge	24.6 ft of line
Max line length	164 ft per submittal, 213 ft per install manual

Sources: NEEP ccASHP list · MrCool Olympus E Star submittal · MrCool Olympus install manual · MrCool Olympus 4th Gen warranty

MrCool's submittal and install manual disagree on max line length (164 ft vs 213 ft); work to the manual that ships with the unit.
"E Star" and the O-ES prefix also appear on an older R-410A Olympus (-230B condensers); confirm R-454B and an outdoor model ending -230C-O1.
The Olympus listings on Amazon are the legacy R-410A Hyper Heat, not this unit.
MrCool's FAQ says an HVAC professional must install it; the warranty's softer "may be necessary" wording doesn't change that.