King County Heat Pumps: Mechanical Approval and Electrical Work

Separate the County From Nearby Cities

King County Local Services issues building and mechanical permits for unincorporated areas. That does not make it the mechanical permitting department for every home in Seattle, Bellevue or another incorporated city. Confirm the parcel’s jurisdiction before selecting an agency in an online application.

The county’s May 2025 residential mechanical handout covers several residential building types, including single-family homes and duplexes. Give the contractor the actual building type and existing permit record. For a condominium, also identify who controls exterior walls and shared equipment areas before settling on a location.

Decide Whether Mechanical Work Is Already Included

The county handout says a separate residential mechanical permit is unnecessary for new installations included with a single-family construction or remodel permit. That is a scope distinction, not permission to leave mechanical work undocumented. Ask the permit holder to show where the heat-pump installation appears in the approved project.

For a replacement outside such a project, discuss the appropriate mechanical application. Ask who requests inspections and who responds if the inspector finds a mismatch between the equipment or location and the submitted information. Write those tasks into the installation agreement.

Check the Outdoor Location Before Ordering

The handout discusses heat pumps projecting into residential setbacks while retaining other restrictions, including utility-corridor, street and sight-distance requirements. Do not turn that passage into a promise that any side-yard position is acceptable. Show the county the proposed location when a boundary or street corner makes the answer uncertain.

Have the installer mark the unit, service access, piping and drainage on a simple site sketch. Compare alternative positions for bedroom noise, maintenance access and winter use. These practical concerns can remain even when a location satisfies the applicable zoning rule.

• Is the proposed unit location consistent with this parcel’s restrictions?
• Where will condensate and defrost water go?
• Can the equipment be serviced without moving fences or stored items?

Close the Mechanical and Electrical Records

The county directs electrical inspection inquiries to Washington Labor and Industries and identifies separate plumbing and gas-piping contacts. Ask the installer which agencies apply to the actual scope, especially if the work adds a circuit, changes service equipment or removes a fuel appliance.

At handoff, request the relevant permit numbers and inspection outcomes, equipment model numbers, control instructions and filter-access demonstration. If another contractor performs the wiring, name who coordinates that visit. Avoid a schedule in which the mechanical crew leaves an installed system waiting indefinitely for a separately arranged connection.

Sources And Local Resources

Official sources checked October 17, 2026. Confirm current requirements with the authority responsible for your property.

• King County Building and Land-Use PermitsUnincorporated jurisdiction, online applications and separate agency inspection contacts.
• King County Residential Mechanical Permits — May 2025May 2025 handout, PDF page 1: residential coverage, mechanical work included with certain building permits, qualified outdoor-unit setback provisions and separate trade permits.