Series photoFujitsu General · Single-Zone
~$2,957
Fujitsu Airstage Altair 500 24,000 BTU
Large rooms in mild climates where a branded 24k is wanted without the XLTH price.
- BTU/h
- 24k
- Volts
- 208/230
- Refrig.
- R-32
- SEER2
- 21.5
- HSPF2
- 10
- Heats to
- 5°F
The maker's photo for this series, not this exact size; the outdoor unit grows with capacity
Fujitsu General · Single-Zone
Fujitsu Airstage KZAH1 Extra-Low-Temp 12,000 BTU
ASUH12KZAS / AOUH12KZAH1
~$3,053approximate retailer price at last check, equipment only
- BTU/h
- 12k
- Volts
- 230
- Zones
- 1
- SEER2
- 30.5
- HSPF2
- 12.7
- Heats to
- -15°F
- Refrig.
- R-32
- Covers
- 500 ft²
- Wi-Fi
- Built in
Best forCold-climate buyers who want the best paper specs in the 12k flagship class and have a Fujitsu Elite contractor nearby.
Overview
Fujitsu is the third name in the trinity owners recommend, and the KZAH1 is the direct descendant of the legendary RLS3H that heated Vermont houses for a decade — RLS3H became LZAH1, which became this R-32 KZ generation. On paper it now beats both rivals: 30.5 SEER2 tops the Mitsubishi FS12NA's 26.3, 12.7 HSPF2 tops everything in the 12k class, and extra-low-temp heating runs to -15°F — two degrees below Mitsubishi's rating — with better-than-nominal capacity holding through 5°F. Built-in WiFi via the Airstage app is standard, a small win over the Mitsubishi FS12NA, which needs a Kumo Cloud adapter. The trade-off is network depth: Fujitsu's US installer base is thinner than Mitsubishi's, so quotes swing more and board-level parts can take days instead of hours in some regions. Equipment runs ~$3,050 and installed packages land at $5,500-$8,000. Failure patterns match the category — blower motors and outdoor inverter boards — and Fujitsu's parts pricing is generally friendlier than Mitsubishi's. If an Elite contractor serves your area, the 12-year warranty makes this arguably the best value flagship.
- 30.5 SEER2 / 12.7 HSPF2 — class-leading efficiency
- Heats to -15°F, below both big rivals' ratings
Cold-weather output
At 5°F it makes more heat than its 47°F rating (104%), according to the certified NEEP listing for this pairing. Fujitsu General rates it to keep running down to -15°F.
- COP at 5°F
- 2.16
- Refrigerant
- R-32
- AHRI cert.
- 214888802
- ENERGY STAR cold climate
- Yes
Pairing: AOUH12KZAH1 with ASUH12KZAS. From NEEP's ccASHP list; a different head or condenser posts different numbers.
Strengths and catches
Strengths
- +30.5 SEER2 beats the Mitsubishi FS12NA and Daikin Aurora outright
- +Built-in WiFi, where the Mitsubishi FS12NA needs a separate Kumo Cloud adapter
- +Current R-32 platform, not closeout R-410A stock
- +12-year warranty available through Fujitsu Elite contractors
Catches
- −Thinner US installer network than Mitsubishi — quote quality varies by region
- −~$3,050 equipment is the priciest 12k in the premium class
- −Proprietary inverter boards; repairs are dealer-parts-only
Questions buyers ask
Does the KZAH1 really keep heating below zero?+
Yes — it's rated for heating operation down to -15°F, below both the Mitsubishi FS12NA and Daikin Aurora ratings, and it descends directly from the RLS3H line that heated Vermont houses for a decade. As with any heat pump, capacity tapers as temperatures fall, so size it to your heating load rather than the cooling label and keep some backup for design-cold nights.
How does the warranty work if I don't use a Fujitsu Elite contractor?+
The base warranty is 5-year parts / 7-year compressor. A registered professional install bumps it to 10 years, and only a Fujitsu Elite contractor gets you to 12. That structure effectively rules out DIY — and since the install involves flaring and evacuation anyway, plan on a $5,500-$8,000 installed package like its Mitsubishi and Daikin rivals.
Is WiFi included or an add-on?+
Built in, controlled through the Airstage app — a real differentiator against the Mitsubishi FS12NA, which needs a separate Kumo Cloud adapter. Like most OEM HVAC apps it's functional rather than slick, but there's no extra hardware to purchase.
If the specs beat Mitsubishi, why doesn't everyone buy Fujitsu?+
Installer coverage. Fujitsu's US network is thinner than Mitsubishi's in many regions, so quote quality and service familiarity vary a lot by zip code, and repairs are dealer-parts-only because of the proprietary inverter boards. If you have a good Fujitsu Elite contractor nearby, the 30.5 SEER2 / 12.7 HSPF2 numbers are the best in the 12k flagship class.
What size room is a 12k head right for?+
Roughly 500 sq ft. In a cold climate the heating load usually governs, so a well-sealed 500 sq ft space is the sweet spot — an older, leakier room that size may want the load math checked before committing.
Similar systems
Everything from Fujitsu GeneralSeries photo
Series photoFujitsu General · Single-Zone
~$3,274
Fujitsu Airstage Orion XLTH 15,000 BTU
Cold-climate bedrooms and living rooms where you want a premium Japanese-brand unit for less than the Mitsubishi FX.
- BTU/h
- 15k
- Volts
- 208/230
- Refrig.
- R-32
- SEER2
- 27.5
- HSPF2
- 12.7
- Heats to
- -15°F
Fujitsu General · Single-Zone
~$2,789
Fujitsu Airstage 9KZAH1 Extra-Low-Temp 9,000 BTU
Small, well-insulated spaces — bedrooms, ADUs, passive-house builds — where maximum efficiency justifies a premium per-BTU price.
- BTU/h
- 9k
- Volts
- 230
- Refrig.
- R-32
- SEER2
- 33.1
- HSPF2
- 13.3
- Heats to
- -15°F