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A contractor quoting a central AC install in Lewis County has to work out what the system is actually being asked to do before they can size it honestly. Homes in Lewis County, WA have essentially no cooling season — no month of the year is warm enough to call for it. A compressor that never starts accumulates no wear on its running parts, but long idle periods leave contactors corroded and refrigerant circuits untested until the one afternoon they matter. The sizing question shifts: the load calculation still has to be done, but the case for the equipment rests on readiness, not on runtime.
Ductwork laid in for one generation of equipment rarely runs where a new central AC system needs it to run, and the gaps show up once a contractor gets into the crawlspace or the walls. Half the homes in Lewis County, Washington were built in 1980 or earlier (2020-2024 ACS 5-year). That means a significant share of the houses here were ducted before the equipment now available to replace them existed. A contractor quoting the job prices the duct work before the unit, because that is where the variables are. The electrical side follows the same logic: service panels in houses of that vintage were not sized for modern cooling loads, and what the new unit actually draws has to be checked against what the house can deliver.
What Gets Installed With a New Central AC
The outdoor condenser unit sits outside the house, usually on a concrete pad along an exterior wall, and it holds the compressor and the coil that releases heat to the outside air. Inside, the air handler mounts in a utility space, basement, or attic and moves conditioned air through the home. These two units are the core of what a contractor puts in.
A copper refrigerant line set runs between the outdoor and indoor units, carrying refrigerant back and forth, and it gets routed along the exterior or through a wall chase. The thermostat goes on an interior wall where it reads the temperature of the living space and tells the system when to run.
The drawing shows the general layout of a central AC system, and a licensed contractor determines exactly how each piece fits the conditions of your house.
Get matched in Lewis CountyLewis County, by the numbers
Half the homes in Lewis County, Washington were built in 1980 or earlier (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesLewis County, Washington holds 36,512 housing units (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesOwners occupy 75.8% of the occupied homes in Lewis County, Washington (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesCodes & Standards Governing Central AC Installation in Lewis County, Washington9 sourced rules and standards
What the installation actually looks like
Split-system central air conditioners rated below 45,000 Btu/h manufactured on or after January 1, 2023 must meet a federal minimum of 13.4 SEER2.
Split-system central air conditioners rated at or above 45,000 Btu/h manufactured on or after January 1, 2023 must meet a federal minimum of 13.4 SEER2.
Split-system central air conditioners manufactured between January 1, 2015 and December 31, 2022 had to meet 13 SEER, the metric that preceded SEER2.
Single-package central air conditioners manufactured on or after January 1, 2023 must meet a federal minimum of 13.4 SEER2.
Space-constrained central air conditioners manufactured on or after January 1, 2023 must meet a federal minimum of 11.7 SEER2.
Federal efficiency standards for split-system central air conditioners and heat pumps are set on each certified combination of outdoor unit and indoor coil rather than on the outdoor unit alone.
Residential and light commercial air conditioning and heat pump systems assembled in the field, including mini-splits and unitary systems, may not be installed on or after January 1, 2025 using a refrigerant with a global warming potential above 700.
A field-assembled system whose specified components were all manufactured or imported before January 1, 2025 carries no installation compliance date under the refrigerant restrictions and may still be installed.
Licensing and Legal Requirements in Lewis County, Washington
Washington requires contractor registration rather than an HVAC licence: every contractor must register with the Department of Labor and Industries, and advertising, bidding or working as a contractor without that registration is a gross misdemeanour.