How Long Does AC Installation Take? (Complete Timeline for 2026)

How Long Does AC Installation Actually Take?

Most Bay Area homeowners want to know one thing before scheduling: will this take all day, or will I have a working system by lunch?

The honest answer depends on the type of job. Here's a breakdown of every scenario.

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Timeline by Installation Type

Replacement of Existing Central AC System

Typical time: 4–8 hours

This is the most common job — your old system died or is past its useful life, your ductwork is in good shape, and you need the equipment swapped out.

What happens during those hours:

Time	Task
Hour 1	Remove old outdoor condenser, recover refrigerant (required by EPA law)
Hour 1–2	Remove old indoor evaporator coil, inspect air handler and ductwork connections
Hour 2–4	Install new outdoor condenser on pad, connect electrical, connect line set
Hour 3–5	Install new evaporator coil, connect to air handler, check all connections
Hour 5–6	Pull vacuum on refrigerant lines (minimum 30-minute deep vacuum), verify system is leak-free
Hour 6–7	Charge refrigerant to manufacturer specification, verify with gauges
Hour 7–8	Commission system: test all modes, verify airflow, check temperature split, calibrate thermostat

New System in Home with Existing Ductwork

Typical time: 1–2 days

If your home has ductwork but you're adding central AC for the first time (perhaps replacing window units), the timeline extends because the line set, drain line, and electrical must be run from scratch.

Day 1: Equipment placement, electrical rough-in, line set installation Day 2: Equipment connection, ductwork modifications (if needed), commissioning and testing

Full System with New Ductwork

Typical time: 3–5 days

If your home doesn't have existing ductwork — common in older Bay Area homes built before central AC was standard — this becomes a major project.

• Day 1: Attic or crawlspace access, trunk line installation
• Days 2–3: Branch duct runs to each room, supply registers cut in
• Day 3–4: Return air system, grilles, air handler platform
• Day 4–5: Equipment installation, refrigerant, commissioning

Alternative: Many Bay Area homeowners with no ductwork choose a ductless mini-split system instead. A 4-zone mini-split installation takes 2–3 days and avoids the ductwork entirely — often at a lower total cost.

Mini-Split (Ductless) Installation

Typical time: 4–6 hours (single zone) / 1–2 days (multi-zone)

Ductless systems are the fastest to install because there's no ductwork involved — but several factors can push a multi-zone job toward 2–3 days.

Single-zone (one room or zone):

• Wall penetration for refrigerant lines and electrical
• Mount indoor unit on wall
• Install outdoor unit on pad or wall bracket
• Connect refrigerant lines, pull vacuum, charge
• Commission and test
• Total: 4–6 hours

Multi-zone (3–4 rooms):

• Each additional indoor unit adds 2–3 hours
• More complex line set routing
• Total: 1–2 full days

What makes ductless installations take longer:

Wall-mounted vs. ceiling-mounted units: Wall-mounted cassettes are straightforward — one penetration through the wall, line set drops down the exterior. Ceiling-mounted cassettes require cutting into the ceiling for the unit housing, which is significantly more labor-intensive.

Plaster ceilings in San Francisco: Many SF homes and older Bay Area buildings have original plaster ceilings. Cutting into plaster cleanly, without cracking adjacent areas, takes considerably more time and skill than cutting drywall. A ceiling cassette installation that takes 2 hours in a newer home can take 4–5 hours in a San Francisco Victorian with plaster.

Multi-story line set routing in San Francisco: SF homes are tall — often 3 stories — and line sets frequently need to run 2–3 floors up, sometimes through the roof. Routing refrigerant lines and electrical through multiple floors, exterior walls, and rooflines adds significant time compared to a single-story ranch home where the line set drops a few feet outside.

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What Actually Happens on Installation Day

Understanding the sequence helps explain why some jobs take one day and others take three.

Step 1: Removal of Old Equipment (1–3 hours)

We start every project by removing the existing equipment. A straightforward removal — outdoor condenser sitting on a pad in the side yard, furnace in a spacious garage — takes about 1–2 hours.

When equipment is in a small attic, tight closet, or high on a platform, removal gets more complicated. Sometimes old equipment has to be cut apart in pieces to get it out of a confined space. Add another hour or two for these situations.

Step 2: Assessment of What's Behind the Old Equipment

This is where surprises happen — and where honest contractors build schedule cushion. Once the old system is out, we can see what was hidden behind it:

• Rusted or deteriorated plenums: Supply and return plenums (the sheet metal boxes that connect the air handler to the ductwork) are often corroded and not visible until the unit is removed. A rusted plenum needs to be rebuilt before a new system goes in.
• Unsealed platforms: When a furnace sits on a platform in an attic or crawlspace, that platform sometimes has gaps that allow the system to pull in debris, insulation, and unconditioned air. We rebuild and seal the platform before installing the new unit.
• Old fiberglass insulation on ducts: We remove deteriorated fiberglass duct insulation and replace it with modern foil-faced bubble wrap insulation, then seal all boots and duct connections.

Step 3: Indoor Unit Installation

With the space prepared, we install the new furnace or air handler and evaporator coil. This is also when we:

• Install new flue piping: A furnace upgrade from 80% to 96% efficiency requires replacing the metal flue pipe with PVC — these high-efficiency furnaces produce condensate that would corrode metal pipe. This adds time but is non-negotiable for code compliance.
• Inspect and modify drain lines: We check the condensate drain, clear any blockages, and bring it to current code. Sometimes this means running a new drain line entirely.
• Check and seal all duct connections at the air handler

Step 4: Outdoor Condenser Installation

The condenser goes in last — after refrigerant lines are run, electrical is connected, and the indoor side is ready. In most Bay Area cities, the condenser sits on a standard concrete or composite pad.

Exception: Hillside homes in Berkeley, Oakland, Lafayette, Moraga, Orinda, and similar areas. Homes on steep lots often have no flat ground where a standard pad can sit level. In these cases, we pour a concrete platform custom-built for the grade. It's more labor-intensive but necessary for a stable, code-compliant installation.

Step 5: Startup, Testing, and Cleanup

Once everything is connected, we pull a deep vacuum on the refrigerant lines, verify there are no leaks, charge the system to manufacturer specification, and run through a complete commissioning checklist. We do a full cleanup of all work areas before we consider the job done.

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Where Equipment Location Adds Time

The "box swap" in a garage (ideal): When we're replacing an existing furnace and AC where the furnace is in a roomy garage, with good access to the condenser and a clear path for the line set, an experienced two-person crew can complete the job in a single day.

Furnace in a small attic (adds a full day): Working in an attic is physically demanding in any season — but in Bay Area summers, attic temperatures routinely exceed 100°F. A project that would take one day in a garage typically takes two days when the furnace is in a cramped attic. The heat forces more frequent breaks, the tight space slows every task, and the equipment itself is harder to maneuver. Expect attic furnace replacements to be two-day projects.

Small closets and utility rooms: Equipment packed into a tight closet — where there's barely room to turn around — similarly slows every step of the process. Plan for an extra half-day to full day over a comparable garage installation.

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What Can Slow Down Your Installation

1. Ductwork Problems

If your ductwork hasn't been inspected in years, technicians sometimes discover significant leaks, crushed sections, or disconnected ducts once they remove the old equipment. These need to be repaired before a new system is installed — or you'll be cooling your attic instead of your home.

Ductwork replacement timelines vary widely based on access:

• Garage or basement with good access: 1 day
• Large open attic: 1–2 days
• Narrow crawlspace: 2–4 days — in some crawlspaces, only one person can fit at a time, which means the work can't be parallelized the way an open space allows

San Francisco metal duct requirement: SF requires rigid metal ductwork — flexible duct is not permitted. Metal ducts are custom-fabricated to the dimensions of each run, require specialized tools to install, and take significantly more time than flex duct. This is a meaningful cost and schedule factor for any San Francisco ductwork project.

How to avoid surprises: Ask for a ductwork inspection before your installation day. We can identify issues in advance and schedule repairs accordingly.

2. Electrical Upgrades

Modern high-efficiency AC systems often require a 240V circuit. If your panel is older or the existing circuit is undersized, an electrician may need to run a new circuit. This can add several hours or require a separate electrician visit.

How to avoid it: We check your electrical panel compatibility during the site assessment before we schedule your installation.

3. Difficult Line Set Routing

In some homes — particularly multi-story Bay Area craftsmans or homes with finished walls and no attic access — routing the refrigerant line set is genuinely difficult. A job that's straightforward in a ranch home with attic access becomes a half-day exercise in a 1920s Berkeley craftsman with plaster walls. San Francisco homes add the further challenge of running lines 2–3 stories up and, in many cases, through the roof.

4. Permit Inspections

California requires permits for HVAC installations. In most Bay Area cities, the permit is obtained before installation and the inspection happens after. However, some cities (notably San Francisco, Oakland, and Berkeley) require an inspection before the system is operational, which may add a day.

We handle all permit applications and scheduling as part of every installation.

5. Equipment Availability

If a specific model is backordered, we either substitute an equivalent or wait for the right equipment. We carry stock of the most common sizes locally to minimize delays for standard jobs.

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How to Prepare for Your Installation Day

A well-prepared home makes the job faster and smoother:

The day before:

• Clear a 3-foot path from your front door to the thermostat, air handler (usually in attic, closet, or utility room), and the outdoor condenser location
• Make sure someone 18 or older will be home for the entire installation
• Confirm your installation appointment and equipment selection

The morning of:

• Unlock any gates leading to the side or back yard where the outdoor unit will be installed
• Move vehicles out of the driveway (installers need to unload equipment)
• Keep pets secured — we'll be moving through multiple rooms and the attic/crawlspace

During installation:

• You don't need to stay in the room where work is happening, but be reachable
• Near the end, a technician will walk you through the system operation, thermostat programming, and filter location

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What We Check Before We Leave

A properly commissioned AC installation isn't just "plug it in and turn it on." Before our crew packs up, we verify:

• Refrigerant charge: Verified with digital manifold gauges, not estimated
• Temperature split: Supply air should be 18–22°F cooler than return air
• Static pressure: Airflow through the duct system is within design parameters
• Electrical: Amperage draw matches nameplate specifications
• Thermostat: Programmed, staged correctly, and tested in both heating and cooling
• Title 24 documentation: Required by California law for all new HVAC installations

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Can I Use My Home During Installation?

Yes. You'll have temporary interruptions to your HVAC system, but the rest of your home remains fully accessible. The main nuisances are:

• Attic hatch access (we'll need occasional access)
• Some dust or debris if ductwork modifications are needed (we protect floors and furniture)
• No heating or cooling for the duration of the job

Most residential AC replacements are completed well within business hours, so you'll have a fully operational system before evening.

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Ready to Schedule?

We serve 50+ Bay Area cities and carry equipment in local stock to minimize delays. Most standard replacements can be scheduled within 3–5 business days.

Schedule your AC installation → or call (925) 578-3379.

Licensed CSLB #1076868 | NATE Certified | EPA 608 Certified