When ductless mini-split is the right answer

Mini-split (ductless) heat pumps are the right call in four specific scenarios across the Bay Area. First: homes with no usable ductwork: common in older Berkeley flats, original Oakland bungalows, and ADUs. Tearing into plaster walls to run new duct trunks costs more than the heat-pump equipment itself. A mini-split skips that entirely.

Second: partial conditioning. You want a master suite cool at night but don’t need (and don’t want to pay to cool) the whole house. A 9,000 or 12,000 BTU/h head solves the problem at a fraction of the cost and operating expense of a central system.

Third: ADU and garage conversions. New livable square footage that the existing central system can’t reach, and shouldn’t reach, because most central systems sized for the original house don’t have the capacity for added space. A standalone 1-ton ductless system is the standard answer.

Fourth: zone-specific load profiles. South-facing rooms with floor-to-ceiling windows have wildly different summer cooling needs than the rest of the house. A central system has to size for the worst room, oversizing every other zone. Mini-splits per zone solve this elegantly. See our ductless mini-split service for install details.

Mini-split vs central heat pump: which to pick

Factor	Mini-split (ductless)	Central ducted heat pump
Existing ducts	Not required	Required (or major retrofit cost)
Whole-home coverage	3-5 heads typical, visible indoor units	One indoor system, hidden in attic/closet
Zone control	Per-head (granular)	Per-zone with motorized dampers (extra cost)
Cost, single zone	$4,500-$7,500 per zone	Not practical (would still be whole-house cost)
Cost, whole home	$15,000-$25,000 for 3-5 head system	$13,000-$17,000 for ducted system
Aesthetics	Wall/ceiling heads visible in each room	Registers only (invisible system)
Best for	ADUs, additions, no-duct homes, master-only	Whole-home replacements with existing ducts

Going with central instead? Try the free central HVAC load calculator for ducted-system sizing.

ADU and garage conversion HVAC

California’s ADU streamlining laws have made backyard ADUs and garage conversions one of the most common HVAC scenarios in the Bay Area in 2024-2026. The default answer for new conditioned space is almost always a 12,000 or 18,000 BTU/h ductless mini-split. Why:

• Compact outdoor unit: a 1-ton outdoor condenser is roughly 30″ wide × 23″ deep, fits in a side yard easily.
• Single penetration: one 3″ hole through the wall for refrigerant lines, drain, and low-voltage. Minimal structural impact.
• Independent system: your ADU tenant’s thermostat doesn’t affect your main house, and vice versa.
• Title 24 compliant: single-zone heat pumps meet all current ADU energy-code requirements without supplemental documentation.
• Rebate-eligible: MCE rebates apply to ADU installs in eligible cities; manufacturer rebates may apply if equipment qualifies.

For garage conversions specifically, mini-split is essentially the only practical answer, running central ductwork into a former garage usually means visible bulkheads or sacrificing closet space. The mini-split head mounts high on the interior wall and stays out of the way.

120-volt plug-in heat pumps, the new category

A growing class of mini-split-style heat pumps plug into an ordinary 120V household outlet, no electrical permit, no panel upgrade, no licensed installer required for the plug-in operation itself. These have exploded in popularity since 2023 for apartments, ADUs, accessory dwellings, and homes where the existing electrical service is already at capacity.

The trade-off: they’re capacity-limited. A 15-amp 120V circuit caps you at roughly 12,000 BTU/h cooling and 8,000-10,000 BTU/h heating, enough for one well-insulated 400-600 sqft room or a small ADU, not enough for a whole-home system. They’re also less efficient (SEER2 14-16 typically) than hardwired 240V models (SEER2 19-26 on premium equipment).

Model	Type	Capacity	Price range
Gradient All-Weather	Window saddle (no drilling)	10,000 BTU/h cool, 9,000 heat	$1,800-$2,400
Midea U-Shaped	Window saddle	8,000-12,000 BTU/h cool	$450-$700 (cooling only, most variants)
Windmill AC + Heat	Window saddle	10,000 BTU/h cool, 9,000 heat	$700-$1,000
Friedrich PHE	Through-wall (sleeve required)	12,000-14,000 BTU/h heat pump	$1,300-$1,700
LG Dual Inverter Window Heat Pump	Standard window unit	8,000-12,000 BTU/h heat pump	$600-$900

When 120V plug-in is the right call: rental properties (no permit, no landlord-modification issues), accessory dwelling units under 600 sqft, single bedrooms or home offices that need quick conditioning, and homes with electrical panels already at capacity where adding a 240V/30A circuit for a hardwired mini-split would trigger a panel upgrade.

When 120V plug-in is NOT enough: whole-home conditioning (capacity won’t reach), heating in CZ12 inland winters (the cheaper models lose meaningful capacity below 30°F: check the model’s low-temp curve), or anywhere needing more than 12,000 BTU/h cooling capacity.

We’ll talk through 120V vs hardwired during the estimate visit if your situation is on the borderline, sometimes the right answer is one 120V unit in the room that matters most rather than a $15K hardwired system you don’t actually need.

Brand comparison: which mini-split actually wins

Five tiers of mini-split brands sell in the Bay Area. Each has a clear sweet spot, and a few have failure modes worth knowing before you commit $10K+ to a system.

Brand	Cold-climate rating	Warranty	Best for
Mitsubishi Hyper-Heat (M-Series)	Full capacity to 5°F, partial to -13°F	12yr compressor / 7yr parts	Premium installs; whole-home multi-zone; clients prioritizing longevity
Daikin Aurora / Atmosphera	Full capacity to 5°F, partial to -15°F	12yr compressor / 12yr parts (registered)	Premium / mid-premium installs; best warranty in category; Andrew is factory-trained on Daikin
Fujitsu Halcyon LX	Full capacity to 5°F	10yr parts (registered)	Mid-premium; quieter indoor units; concealed-duct options popular
Bosch IDS / Climate 5000	Full capacity to -4°F (IDS Premium)	10yr parts / 6yr compressor	Mid-tier; good cold-climate spec; thinner installer network in Bay Area
Cooper & Hunter PEAQ	Full capacity to 5°F	10yr parts / 7yr compressor (registered)	Value-premium hybrid; best price-to-performance in the cold-climate category
Pioneer / Senville	Effective to ~14°F	5-7yr parts / 5yr compressor	Value tier; DIY-friendly pre-charged kits; OK for mild CZ3 only
MRCOOL DIY	Effective to 5°F (newer models)	7yr parts / 5yr compressor	DIY install pre-charged lines; we DON’T install DIY kits (warranty void if pro touches)

How we recommend: For a Tri-Valley install where the customer expects 15+ years of service and wants the equipment to perform well in cold mornings, Daikin or Mitsubishi are the defaults. For East Bay coast (CZ3) installs where the climate is mild and budget matters, Cooper & Hunter PEAQ is often the best value per dollar. Fujitsu wins when the customer prioritizes quiet operation (the indoor units run noticeably softer at low fan speeds). Bosch is fine but the installer/parts network is thinner here than on the East Coast.

Brands we avoid: No-name Amazon-listed brands with no US parts distribution. A failed compressor on a no-name brand can mean 8-12 week wait for parts versus 1-3 days for the brands above. We’ve seen this kill customer comfort in the middle of summer; we’d rather not put you through it.

Andrew is factory-trained on Daikin (Houston, 2025) and we are an authorized Daikin dealer. We install all the brands above on customer request, the trained-installer relationship just means Daikin is what we’d put in our own house.

BAAQMD Rule 9-4: what the Bay Area gas-ban schedule actually says

Bay Area Air Quality Management District Rule 9-4 phases out the sale of certain natural-gas appliances at the time of replacement to reduce regional nitrogen-oxide emissions. The practical timeline as enforced:

• 2024: Effective date for ultra-low-NOx residential gas water heaters (existing equipment grandfathered).
• 2027: New gas water heater sales banned at point of replacement in most BAAQMD jurisdictions. Replacements after this date must be zero-NOx (electric heat-pump water heaters in practice).
• 2029: Gas furnace replacement restrictions expand. Furnaces specified for <65,000 BTU/h input become zero-NOx-only at point of replacement.

Translation: a gas furnace bought in 2026 will probably function for its full 15-20 year service life, but the equipment you can legally buy to replace it in 2028+ will be much more limited. Heat-pump-based systems (central or ductless mini-split) are the future-compatible direction for any homeowner planning to stay 10+ years.

Frequently asked questions

Ready to plan a real install?

We size each zone on-site, walk you through equipment options, and write you a quote that holds for 30 days:

• Ductless mini-split installation: single-zone or multi-zone systems
• Central heat pump installation: if existing ducts are workable
• Full HVAC installation: new construction or full replacement
• Maintenance plans: extend equipment life

Related reading: Heat pump vs mini-split · California HVAC rebates 2026 · What heat pump installation actually costs · What size heat pump do you need.