Larger homes, multiple zones
Larger two-story homes often run two ducted systems, one per floor. Replacing both at once can simplify equipment and warranties; replacing them one at a time spreads the cost. Either way, each system needs its own load calculation, duct test and verification. Larger homes also earn a larger MCE rebate, since it is calculated per 500 sq ft.
| Situation | Common approach |
|---|---|
| Two furnaces + two ACs | Two ducted heat pumps, each sized by Manual J |
| One system, hot upstairs | Zoning, a second system, or a ductless head upstairs |
| Bonus room or casita | A single-zone mini-split |
Permits: Danville vs County
Danville
The Town of Danville issues building permits through its Permit Center (Danville Permit Center).
Alamo, Blackhawk, Diablo
Unincorporated, so Contra Costa County issues permits (County permits).
HOA approvals for outdoor units
Blackhawk's HOA has an architectural review application for exterior changes (Blackhawk HOA), and Diablo has its own property owners' association. Get approval for the outdoor unit location and any screening before the install date.
Rebates and cost
Danville and unincorporated Contra Costa are MCE territory. As of October 4, 2026, MCE pays up to $400 per 500 sq ft for heat pump HVAC; because the amount is calculated per 500 sq ft, larger homes qualify for more if they meet MCE's rules. Bay Area whole-home installs typically run $14,000–$22,000+ per system; see the cost guide and rebate table.
Systems that fit
Furnace + AC to heat pump for ducted homes, and mini-splits for bonus rooms and casitas.
Danville questions
Do I need HOA approval for an outdoor heat pump unit in Blackhawk?
Blackhawk's HOA runs an architectural review process for exterior changes, which typically covers new outdoor equipment. Submit before installation; other HOAs in the area have similar rules.
Who issues permits in Danville vs Alamo?
Danville has its own Permit Center. Alamo, Blackhawk and Diablo are unincorporated, so permits go through Contra Costa County.