Heating in California
California's climate ranges from mild coast to cold mountain, so heating needs vary widely. This page covers furnace types, heat pumps, radiant and wall heaters, and the carbon monoxide safety rules that apply to every California home.
Last updated: 2026-09-15
Gas furnaces and AFUE
AFUE measures how much fuel becomes heat. Single-stage, two-stage, and modulating furnaces differ in how precisely they match demand. Higher AFUE lowers operating cost but raises the purchase price.
Heat pumps and electric furnaces
Heat pumps are the state's preferred heating path for electrification. Electric (resistance) furnaces are simple but cost more to run in cold climates. Match the technology to your rate structure and climate.
Hydronic, radiant, and wall furnaces
Hydronic and radiant systems heat water or floors; wall furnaces heat one room and are common in older California homes. Each has distinct maintenance, efficiency, and code considerations.
Carbon monoxide safety (California law)
California requires approved carbon monoxide detectors outside each sleeping area and on every floor of dwellings with a fuel-burning appliance or attached garage. Test detectors and replace them per the manufacturer's schedule.
Heat exchanger cracks and venting
A cracked heat exchanger can leak carbon monoxide and usually means replacing the furnace. Proper venting and combustion air are required; gas line work may need a plumber (see Plumbers.com.AI).
Homeowner checklist
- Install and test CO detectors per California law
- Ask for the AFUE rating and stage type
- Require a permit for any replacement
- Ask whether venting and combustion air meet code
- Get warranty terms in writing