Where can my ADU's outdoor heat pump unit go, and what clearances apply?

Your outdoor unit can usually sit on a pad or wall bracket beside the ADU, as long as it meets the manufacturer's clearances, stays at least 5 feet from any dryer vent outlet and complies with your city's zoning and noise rules. The best spot balances a short line set, free airflow, service access and distance from bedrooms and neighbors.

Clearances to plan around

• Dryer vents: Section 150.0(h)3A of the 2025 Energy Code requires outdoor condensing units to be at least 5 feet from the outlet of any dryer vent. Lint and moist exhaust foul the coil.
• Manufacturer clearances: each model specifies minimum distances to walls, overhangs and obstructions for intake and discharge air, plus service space. Install to those figures.
• Service access: the California Mechanical Code requires equipment to be accessible for service. Avoid tucking the unit where a technician cannot reach its panels.
• Ventilation intakes: if your ADU uses supply or balanced ventilation, its outdoor air intake must comply with California Mechanical Code Section 402.4.1, and the CEC advises locating intakes away from known contaminant sources. Keep the condenser and dryer vent out of that area.

Zoning, setbacks and noise

Whether a unit can sit in a side or rear setback, and how loud it may be at the property line, are local decisions. Many California cities regulate where mechanical equipment can go and have noise ordinances that limit sound at property lines, sometimes with stricter limits at night. Check your city's zoning code and ask the planning counter before you lock in the location.

To keep noise down:

• Compare manufacturers' published sound ratings; variable-speed units can run quieter at part load.
• Keep the unit away from bedroom windows, yours and your neighbor's.
• Use vibration isolation pads or brackets, and avoid mounting on a wall shared with a bedroom.
• Avoid tight inside corners and narrow side yards where sound reflects and discharge air recirculates.

Other placement details

• Heat pumps shed water during defrost, so place the unit where that water will not pool on a walkway or freeze in cold climates.
• Raise the unit above grade and, in snow areas, above expected snow depth, following the installation manual.
• Keep the line set within the manufacturer's length and rise limits.
• Provide the disconnect the electrical code requires near the unit, and include the circuit in the electrical load calculation.

What it means for your mechanical plan

• Show the unit on the site plan with dimensions to property lines, openings and the dryer vent.
• Note the pad or bracket, the manufacturer's clearances and the disconnect.
• Coordinate with the architect so the location works with setbacks, landscaping and access paths.

An outdoor unit shown without its location or setbacks is a frequent correction; see common HVAC mistakes on ADU projects and the ADU mechanical guide.

Sources: energy.ca.gov, energy.ca.gov.