Do heat pumps work in Fairfield winters?

Winters in Fairfield are mild, so heating efficiency matters less than cooling. The average winter low is 38°F, and the heating season adds up to 2,446 heating degree days (NOAA 1991-2020 normals).

How much does it cost to run a heat pump in Fairfield?

A typical 3-ton central heat pump (17.0 SEER2, 9.0 HSPF2) uses about $1,325 of electricity a year for heating and $666 for cooling in Fairfield, at the California average of 33.1¢/kWh. The most efficient models cost less - see the rankings above.

Is a heat pump cheaper than a gas furnace in Fairfield?

Not on heating alone at today's prices: about $1,325 a year with a typical heat pump versus $803 with a 95% gas furnace (California averages: 33.1¢/kWh, $2.12/therm). A high-HSPF2 model narrows the gap, and a heat pump also replaces the air conditioner. Against propane, oil or electric heat it is usually far cheaper.

What size heat pump do I need for a 2,000 sq ft house in Fairfield?

With average insulation, roughly a 2.5-ton system: the estimated cooling load is 30,600 BTU/h and the heating load 30,000 BTU/h. Use the size calculator for your own house, and ask installers for a Manual J calculation.

Mild winters · Warm summers

Best heat pumps for Fairfield, CA

Winters in Fairfield are mild, so heating efficiency matters less than cooling.

A typical heat pump costs about $1,325 a year to heat a house here and $666 to cool it. A 95% gas furnace would cost $803 for the same heat.

This guide also covers Vacaville, which share Fairfield's weather station and climate data.

Nights at or below 0°F0 a year
Nights at or below 20°F0.3 a year
Days at or above 90°F88 a year
Average winter low38°F
Average summer high93°F
Electricity33.1¢ per kWh
Natural gas$2.12 per therm

Cheapest to run in Fairfield

Ranked by yearly electricity cost in this climate, so the balance of heating and cooling efficiency is the one that matters here.

Best 12,000 BTU mini-split

Fujitsu AOUH12KTAP1

12,000 BTU mini-split · AIRSTAGE H-Series · cold-climate certified

SEER2: 31.5
HSPF2: 13.7
Per year here: $410

For one large room.

Full specs and running cost

Best 24,000 BTU mini-split

SLIMAIR SHC24VH2AG

24,000 BTU mini-split · SHC Series · cold-climate certified

SEER2: 27.5
HSPF2: 14.5
Per year here: $823

For open-plan floor or small home.

Full specs and running cost

Best 3-ton central heat pump

TOSHIBA CARRIER MCY-MUB0368HS2P-UL

3 ton central · cold-climate certified

SEER2: 29.7
HSPF2: 12.2
Per year here: $1,359

For typical whole house.

Full specs and running cost

Running cost calculator for Fairfield

Pre-filled with Fairfield's climate and California prices. Pick a model, tell it what you heat with today, and add your quote.

Heat pump $1,261/yrYou save $130/yrSee details ↓

1. Where you live

StateCityElectricity ¢ per kWh

Adjust heating and cooling hours

Filled in from your city's climate. Change them if you run the system much more or less than usual.

Cooling hours full-load hours per yearHeating hours full-load hours per year

2. The heat pump pick a model or type its ratings

Find a model (fills in the ratings below)

SEER2 cooling efficiencyHSPF2 heating efficiencyCooling capacity BTU/hHeating capacity BTU/h

3. What it replaces

Current heatingFurnace efficiency (AFUE %)Gas price, $/thermCurrent coolingOld AC rating SEER2 (10 ≈ 15+ years old)

4. Price replace the example with your quote

Installed price, $Rebates and incentives, $ utility, state

Heat pump, per year: $1,261
Current system, per year: $1,391
You save per year: $130
Payback: Over 30 years
Net after 10 years: -$7,698

Cooling $378Heating $883Electricity used: 3,807 kWhSaved vs. a minimum-efficiency heat pump: $327

Estimates use the unit's rated SEER2 and HSPF2, full-load hours derived from NOAA 1991-2020 degree days, average residential electricity prices from the U.S. EIA (12 months to July 2026) and fuel prices from EIA (2025 for natural gas, week of 2026-10-05 for propane and heating oil). Very cold days that need backup heat are not modelled. Federal minimum for comparison: 14.3 SEER2 / 7.5 HSPF2.

More for Fairfield

Top 5 12,000 BTU mini-splitsfrom $410/yr

Model	SEER2	HSPF2	Per year
Fujitsu AOUH12KTAP1	31.5	13.7	$410
MDV MOX430-12HFN1-MZ60W	27.5	14.5	$412
Goodman MSH123G26MCAA	27.5	14.5	$412
Fujitsu AOUG12LZAS1	29.4	12.9	$437
Fujitsu AOUH12KZAH1	30.5	12.7	$437

All 12,000 BTU mini-splits

Top 5 24,000 BTU mini-splitsfrom $823/yr

Model	SEER2	HSPF2	Per year
SLIMAIR SHC24VH2AG	27.5	14.5	$823
MDV MOD30-24HFN10-M1X	22.3	13.5	$928
Mainline ML24HP230NEXH-O	22.3	13.3	$937
ComfortStar CHF3-24CD(O)	22.3	13.3	$937
Arcoaire D5CSHAH24AAK	21.2	13.5	$945

All 24,000 BTU mini-splits

Top 5 3-ton central heat pumpsfrom $1,359/yr

Model	SEER2	HSPF2	Per year
TOSHIBA CARRIER MCY-MUB0368HS2P-UL	29.7	12.2	$1,359
LG KUSXA361A	23.5	10.5	$1,618
LG KUSXB361A	22.0	10.3	$1,673
Trane 5TWV0X36A1	21.0	10.5	$1,675
Lennox SL22KLV-036-230A	20.5	10.5	$1,689

All 3-ton central heat pumps

Heat pump vs. gas, propane and oilgas is cheaper to run

Yearly cost to heat a typical house (36,000 BTU/h of heat, 1,000 full-load hours) at California prices.

Natural gas furnace, 95% AFUE$803/yr
Natural gas furnace, 80% AFUE$954/yr
Propane furnace, 95% AFUE$1,107/yr
Heat pump (typical, 9.0 HSPF2)$1,325/yr
Heating oil, 85% AFUE$1,827/yr
Electric baseboard or furnace$3,496/yr

Electricity and natural gas: California residential averages from the U.S. EIA; propane and heating oil: latest EIA weekly prices.

Month by monthpeak $295 in December

Heating and cooling degree days (NOAA 1991-2020 normals) and what a typical 3-ton heat pump costs in each month at 33.1¢/kWh.

Month	Heating DD	Cooling DD	Cost
January	538	0	$291
February	380	0	$206
March	301	2	$164
April	189	18	$111
May	66	98	$83
June	8	247	$123
July	0	372	$178
August	0	337	$161
September	6	248	$122
October	83	68	$78
November	332	2	$180
December	544	0	$295

What size heat pump for a Fairfield home?2.5 ton for 2,000 sq ft

1,000 sq ft house1.5 ton · heating load 15,000 BTU/h
1,500 sq ft house2 ton · heating load 22,500 BTU/h
2,000 sq ft house2.5 ton · heating load 30,000 BTU/h
2,500 sq ft house3 ton · heating load 37,500 BTU/h

Average insulation, 8 ft ceilings. Size calculator for your own home

Questions4

Do heat pumps work in Fairfield winters?: Winters in Fairfield are mild, so heating efficiency matters less than cooling. The average winter low is 38°F, and the heating season adds up to 2,446 heating degree days (NOAA 1991-2020 normals).
How much does it cost to run a heat pump in Fairfield?: A typical 3-ton central heat pump (17.0 SEER2, 9.0 HSPF2) uses about $1,325 of electricity a year for heating and $666 for cooling in Fairfield, at the California average of 33.1¢/kWh. The most efficient models cost less - see the rankings above.
Is a heat pump cheaper than a gas furnace in Fairfield?: Not on heating alone at today's prices: about $1,325 a year with a typical heat pump versus $803 with a 95% gas furnace (California averages: 33.1¢/kWh, $2.12/therm). A high-HSPF2 model narrows the gap, and a heat pump also replaces the air conditioner. Against propane, oil or electric heat it is usually far cheaper.
What size heat pump do I need for a 2,000 sq ft house in Fairfield?: With average insulation, roughly a 2.5-ton system: the estimated cooling load is 30,600 BTU/h and the heating load 30,000 BTU/h. Use the size calculator for your own house, and ask installers for a Manual J calculation.

Nearby cities

Climate: NOAA 1991-2020 normals, station VACAVILLE NUT TREE AP (14 km away).