Heat Pump Installation and Repair in Mill Valley

What people call us about

Certain patterns lead to a heat pump conversation here. A gas furnace that short-cycles, bangs on ignition, or throws a flame-sensor fault every few weeks. A wall heater in an older canyon house that heats one room and nothing else. A floor that never gets comfortable no matter what the thermostat reads. A house that feels clammy in a way more heat does not fix, which is a moisture problem, not a temperature one.

On existing heat pumps the failures are rarely exotic. Capacitors and contactors lead. After those: a reversing valve that sticks and strands the system in one mode, a defrost board or sensor that stops sequencing correctly, and a slow leak at a flare or service valve that quietly bleeds capacity over two seasons. Outdoor coils packed with redwood duff are close to universal on shaded lots, and a coil that cannot breathe raises head pressure and shortens compressor life. Damp shade adds biological film on blower wheels and coils, and condensate lines terminating in a crawlspace instead of a routed, sloped, discharged path.

Load, path, panel, property line, in that order

We work these projects in that order, and the order matters. Answering out of sequence is how a house ends up with the wrong equipment, in the wrong place, on a circuit the panel cannot carry.

1. Load. A room-by-room calculation built on the actual construction, orientation, glazing, insulation and infiltration. This is the step most often skipped, and skipping it produces an oversized system. Oversizing punishes a heat pump harder than a furnace: the equipment satisfies the thermostat quickly, shuts off, and never runs long enough to pull moisture from the air. In a damp house that worsens the clamminess while the display reads perfect.

2. Path. How conditioned air or refrigerant reaches the rooms that need it. Existing ducts get tested before anyone assumes they can carry a new airflow. With no ducts, the options are wall or floor-mounted indoor units, slim-duct units hidden in a soffit or closet, or a small duct system built into available framing.

3. Panel. A heat pump needs a dedicated 240-volt circuit sized to the equipment. When the design includes electric resistance strips as auxiliary heat, that load can run several times the compressor's, and it is usually what pushes a marginal panel over the line. Specifying it correctly often keeps a project from also becoming an electrical panel upgrade. We hold the electrical license too, so we calculate rather than guess.

4. Property line. Where the outdoor unit can legally sit. In Mill Valley that is a permit requirement with teeth, and the constraint that most often reshapes a design.

Permits, code, and which agency has jurisdiction

A Mill Valley mailing address does not always mean a Mill Valley permit. Several areas carrying a Mill Valley address sit outside the city limits in unincorporated Marin County, where the Marin County Community Development Agency is the permitting authority instead. Submittal requirements, fees and inspection scheduling all differ. We confirm the jurisdiction before an application goes anywhere, because filing with the wrong agency costs weeks.

State energy code applies to replacements, not only new construction. California's 2025 Building Energy Efficiency Standards took effect January 1, 2026, per the California Energy Commission. Compliance documentation belongs in the permit package, and depending on scope, third-party verification may be required. We prepare that paperwork.

Mill Valley sits fully inside the Bay Area Air Quality Management District, which is why the gas-appliance question reaches homeowners here at all. BAAQMD adopted zero-NOx requirements for residential gas water heaters, with dates that land on different unit sizes in different years across 2027 and 2031, and that govern what may be sold or installed rather than what you may keep, and a companion rule covering fan-type residential central furnaces follows on a later phase. None of it requires removing a working gas furnace. It governs what can be installed going forward, on dates still in motion, so we confirm requirements at project time.

Refrigerant matters on the equipment side. R-22 production and import in the United States ended in 2020, so repairing a pre-2010 system depends on reclaimed or stockpiled supply, which pushes those systems toward replacement. R-410A is being phased down under the AIM Act and new equipment is moving to lower global warming potential refrigerants, because newly manufactured residential and light commercial equipment has to sit under a 700 GWP limit. A working R-410A system does not need replacing.

What drives the cost of a project here

We give a fixed number before work starts. These variables move it, roughly in order of influence.

• Whether a usable duct system exists. Reusing sound ducts is the largest cost difference between two otherwise identical houses.
• Number of zones. Each indoor unit or zone damper adds equipment, piping or duct, controls and labor. Zoning a stacked hillside home costs more than a single-story ranch, and is usually worth it.
• Electrical scope. A dedicated circuit and disconnect is routine. A service upgrade, a subpanel, a long conduit run from a downhill panel, or a load-management device is not.
• Outdoor placement. A level side-yard pad is the low end. A structural wall bracket, roof curb, sound barrier, or a long line set routed to the only compliant spot all add work.
• Site access. Long stair runs, steep driveways, and a crawlspace you enter on your stomach change labor hours before anyone touches a tool.
• Equipment tier. Single-stage, two-stage and variable-capacity inverter systems behave differently on comfort, noise and efficiency.
• What is being removed. Older systems sometimes carry duct wrap or mastic that should be tested first, and that step belongs in the schedule, not in a day-two surprise.

Rebates and incentives, with current status

MCE is the community choice energy provider for Marin County and lists rebates for heat pump heating and cooling on its home electrification page, routing customers to its rebate and incentive finder and to participating contractors. Terms shift, so we verify what applies to your equipment and account before specifying anything.

The conditions on MCE's heat pump rebates are timing conditions rather than amounts. You need twelve months of ownership and residency in a single-family detached home inside MCE territory. A participating contractor has to file for you. And the application has to precede the installation, because MCE will not apply a rebate after the fact. On a Mill Valley job that matters more than usual, because the heat pump itself sits on the city's slower minor-permit track and the sequencing has to hold across both.

Maintenance in a damp, shaded microclimate

A heat pump works in both seasons, so it logs roughly twice the run hours of a cooling-only condenser. Maintenance is not optional on equipment that never gets an off-season, and twice a year is the right cadence.

Keep the outdoor coil clear. Under a redwood canopy, needles and duff pack into the fins and moss establishes itself on shaded units. Restricted airflow there cuts capacity in both modes and raises compressor discharge temperature, a wear mechanism rather than a mere efficiency loss. Trimming vegetation back also supports defensible space.

Have the refrigerant charge verified annually. Variable-capacity inverter equipment is more charge-sensitive than older single-stage machines, and a small undercharge a 20-year-old condenser would shrug off shows up as noticeably weaker heating on a cold morning. Check defrost operation before winter too: in damp coastal-influenced air, coils frost at higher temperatures than they do inland.

Confirm the thermostat is configured for heat pump staging rather than furnace logic. Controls that call electric auxiliary heat too eagerly run up a bill the compressor could have handled alone. Our maintenance plans cover both modes.

Power outages and all-electric heating

A heat pump is an electric appliance, and Mill Valley's wooded hillsides sit in territory where PG&E may turn off power during severe weather to prevent wildfire, through its Public Safety Power Shutoff program. If riding through an outage matters, raise it during the design, because the heat pump's draw is a large input into sizing. We are a Certified Generac Generator installer and handle the electrical scope in-house; battery storage paired with solar is the other route.

How to choose a heat pump contractor in Mill Valley

Five questions separate a real proposal from a guess.

1. Did you do a room-by-room load calculation, and can I see it? Tonnage derived from square footage is not a load calculation. Ask for the output. 2. Where is the outdoor unit going, and what does the sound calculation show at the property line? Anyone who has pulled a mechanical permit in this city will have that ready. 3. Did you measure the electrical service, or assume it? Ask whether available capacity was calculated with the new equipment included, auxiliary heat and all. 4. Who pulls the permit? The licensed contractor, always. Being asked to pull an owner-builder permit for work a contractor performs is a warning sign. 5. Is the indoor and outdoor equipment a matched, rated combination? Mismatched components do not perform to either unit's published ratings, and those ratings are what code documentation and incentives rely on.

C-20 covers the mechanical scope and C-10 the electrical. We hold both, so one company owns the whole system rather than two trades pointing at each other. If the visit turns up an aging furnace or water heater, we scope those too.

What North Bay homeowners say

Two reviews from North Bay customers on heat pump work: