TOSOT TW09HXP2A1AO

Name: TOSOT TW09HXP2A1AO
Brand: TOSOT

Matched with the TW09HXP2A1AI indoor unit, this system is certified to the ENERGY STAR cold-climate criteria and publishes 10.00 HSPF2 and 27.00 SEER2, with 9,900 BTU/h of heating at 5°F.

Heating capacity of the TOSOT TW09HXP2A1AO at three outdoor temperatures, in BTU per hour. Paired with TW09HXP2A1AI: 9,900 at 5°F, 8,400 at 17°F, 10,000 at 47°F.

Cold-climate certified by ENERGY STAR. Paired with TW09HXP2A1AI. Points are the only three heating capacities the dataset publishes for this system; the lines between them are drawn to join those points and are not measurements. ENERGY STAR Certified Heat Pumps, retrieved 2026-10-16.

HSPF210.00Btu/Wh, seasonal heating
SEER227.00Btu/Wh, seasonal cooling
COP at 5°F1.87at that test point
Capacity at 5°F9,900BTU/h
Share of 47°F capacity99.0%ours: 5°F ÷ 47°F

What these numbers are and are not. SEER2, EER2, HSPF2 and the COP at 5°F are results from a standard rating procedure, measured at fixed temperatures and airflow in a laboratory. They are not predictions for your house, your climate or your winter. Two systems with the same HSPF2 can use different amounts of electricity in the same building, and the same system will perform differently in Boston and in Atlanta. Use the published capacity at 5°F to judge whether a system still produces heat on a cold night; use HSPF2 only to compare systems with each other.

TOSOT TW09HXP2A1AO published specifications

Every figure below is the value the dataset publishes for ENERGY STAR ID 2409861. Nothing is calculated except the two rows marked as ours.
Outdoor unit	TW09HXP2A1AO
Indoor unit	TW09HXP2A1AI (Pular)
Cold-climate certified	Yes
ENERGY STAR Most Efficient	Yes
SEER2	27.00 Btu/Wh
EER2	14.55 Btu/Wh
HSPF2	10.00 Btu/Wh
Cooling capacity	9,100 BTU/h
Heating capacity at 47°F	10,000 BTU/h
Heating capacity at 17°F	8,400 BTU/h
Heating capacity at 5°F	9,900 BTU/h
COP at 5°F	1.87
Compressor staging	Continuously variable
Refrigerant	R-410A
Date certified	2025-02-17
ENERGY STAR ID / AHRI reference	2409861 / 211177518
5°F capacity as a share of 47°F (ours)	99.0%
Capacity class (ours)	9,000 BTU/h nominal

Source. ENERGY STAR Certified Heat Pumps, U.S. EPA, retrieved 2026-10-16 from the dataset's Socrata API. Record identified by ENERGY STAR ID 2409861, AHRI reference 211177518. Certification partner: Gree Electric Appliances Inc. of Zhuhai. Model numbers are reproduced exactly as published, including the asterisks ENERGY STAR carries as the manufacturer's wildcard for trim variants.

What the published capacities say about cold weather

A heat pump moves heat from outdoor air, so the colder that air gets, the less heat there is to move. The dataset publishes capacity at three outdoor temperatures, and the shape between them is the single most useful thing on this page. For the TW09HXP2A1AO paired with the TW09HXP2A1AI:

At 47°F it delivers 10,000 BTU/h.
At 17°F it delivers 8,400 BTU/h.
At 5°F it delivers 9,900 BTU/h, which is 99.0% of the 47°F figure.

ENERGY STAR lists this system as meeting its cold-climate criteria, which the program describes as better low-temperature heating performance, suitable for use as a home's sole heating source. That is the program's judgement on the published test data, not a promise about any particular winter or any particular house.

Running cost for a 9,000 BTU/h system like this one

Worked as an illustration, not a quote: a house that burned 600 therms of gas in a year through an 80% AFUE furnace needed about 48.0 million BTU of delivered heat. At $1.50 a therm that gas cost $900. Delivering the same heat with a heat pump rated at 10.00 HSPF2 takes 4,800 kWh, which at $0.18 a kWh costs $864. The two costs are equal at $0.188 a kWh.

Those four prices are not your prices, and HSPF2 is a rating-condition figure rather than a seasonal measurement for your climate. Change every input in the running-cost calculator, which shows each formula as it works.

Comparable systems

Same nominal capacity class (9,000 BTU/h), closest published HSPF2 to this one. Colour marks cold-climate certification.

Daikin RX09BXVJU Standard
HSPF2 10.00 · SEER2 20.00 · 5,800 BTU/h at 5°F
GREE GWH09AGCXD-A3DNA1A/O Cold-climate
HSPF2 10.00 · SEER2 27.00 · 9,900 BTU/h at 5°F
Mitsubishi Electric MUZ-FS09NAH*** Cold-climate
HSPF2 10.00 · SEER2 29.80 · 11,300 BTU/h at 5°F
Daikin RXF09AXVJU Standard
HSPF2 10.20 · SEER2 21.00 · 4,900 BTU/h at 5°F
Daikin RXF09BVJU* Cold-climate
HSPF2 10.20 · SEER2 21.00 · 7,700 BTU/h at 5°F

More: all 92 certified systems, or the explainer on SEER2 vs HSPF2.