Air conditioner installation sized to your house, not a guess
A load calculation sets the size, the installation follows the manufacturer's instructions line by line, and the system is tested under real operating conditions before you sign off.
Walk through an install dayReplacing or adding a cooling system the right way
A new air conditioner is a long-term purchase, and the quality of the installation has as much influence on comfort, efficiency and lifespan as the brand name on the cabinet. A well-matched condenser and indoor coil, correct refrigerant charge, clean brazed joints and a properly leveled pad give the equipment the conditions it was engineered for. Skip any of those details and even premium equipment will underperform.
This page covers replacing an existing air conditioner and adding cooling to a home that already has ductwork, such as a house heated by a furnace. If your home has no ducts at all, the central air installation page explains that larger project in detail. We also install ductless mini-split systems for rooms or additions that the main system cannot reach well.
Every installation begins with a visit to measure the home and look at the existing equipment, electrical service, ductwork and drainage. You receive a written proposal with the equipment model numbers, the scope of work and a flat price, so there is no confusion about what is included.
Installation at a glance
- Sizing method
- Manual J room-by-room load calculation
- Refrigerants
- Current low-GWP systems such as R-454B or R-32
- Handoff
- Commissioning readings recorded for you
When a replacement makes more sense than another repair
No single factor decides it, but several of these together usually tip the balance.
The system is well past its middle age
Most central air conditioners last somewhere in the range of 12 to 17 years depending on climate and care. Past that point, major repairs become harder to justify.
A major component has failed
A dead compressor or a leaking evaporator coil on an older system can cost a substantial fraction of a new installation, with the rest of the system still aging.
It uses a refrigerant being phased out
Systems built for R-22 depend on a refrigerant that is no longer produced, so every leak repair gets more expensive as reclaimed supply shrinks.
Some rooms never get comfortable
Hot upstairs bedrooms and a cold basement often point to sizing or duct problems. A replacement is the moment to correct them instead of copying the old setup.
Humidity stays high even when it is cool
An oversized system cools the air quickly and shuts off before it removes moisture, leaving the home clammy. Proper sizing fixes the cause.
Summer bills keep creeping up
Aging compressors, worn motors and dirty coils all draw more power for the same cooling. A modern high-efficiency unit uses noticeably less electricity for the same comfort.
From first measurement to final test
Home evaluation and load calculation
We measure rooms, windows and insulation levels and account for orientation, then run a Manual J calculation to find the cooling capacity the home actually needs.
Equipment selection and written proposal
You see matched condenser and coil options at different efficiency levels, with model numbers, warranty terms and a flat installed price for each.
Removal and site preparation
Old refrigerant is recovered into certified cylinders, the old equipment is removed, and the pad, line set route, electrical disconnect and drain are prepared or upgraded.
Installation and brazing
The line set is brazed with nitrogen flowing to prevent internal scale, then pressure tested and evacuated with a deep vacuum confirmed on a micron gauge.
Commissioning and walkthrough
Charge is set by superheat or subcooling, airflow and temperature split are measured, and you get a walkthrough of the thermostat, filter and maintenance needs.
The installation details that decide how long a system lasts
Two steps separate a careful installation from a rushed one, and neither is visible once the job is done. The first is brazing with dry nitrogen flowing through the copper. Without it, heat creates a layer of oxide scale inside the pipe that breaks loose over time and can clog metering devices and damage compressors. The second is evacuation. Moisture and air left in the system react with refrigerant oil and form acids. Pulling a deep vacuum and confirming it holds on a micron gauge proves the system is dry and tight before refrigerant is released into it.
Refrigerant charge is the other critical number. Many outdoor units ship pre-charged for a certain line length, and the actual line length in your home is almost never exactly that. Setting the charge by measuring superheat or subcooling, as the manufacturer specifies, is what lets the system reach its rated efficiency and capacity. We record those readings, along with static pressure and temperature split, so there is a baseline for future service visits.
About the new refrigerants
New residential air conditioners now use lower global warming potential refrigerants such as R-454B or R-32, which are classified as mildly flammable and require specific handling and installation practices. Our technicians follow those manufacturer and code requirements on every install.
What happens on installation day
A typical air conditioner replacement begins with protecting your home. Floors along the path between the door and the equipment are covered, and furniture near the indoor unit is moved or protected. The crew then shuts off power at the disconnect and the panel and recovers the refrigerant from the old system into a recovery cylinder, because venting it to the atmosphere is illegal.
The old condenser is removed and the pad is checked for level and condition. A new pad goes in if the old one has sunk or cracked. Indoors, the coil above the furnace or inside the air handler is replaced with the one matched to the new condenser. Where the line set is being reused, it is flushed and inspected; where the old line set is the wrong size, damaged or routed poorly, a new one is run.
Brazing is done with nitrogen flowing through the lines to prevent scale. The system is pressure tested with nitrogen to confirm there are no leaks, then evacuated with a vacuum pump and micron gauge until the moisture and air are removed. Only then are the service valves opened and the charge adjusted to the manufacturer's specification.
Before leaving, the installer confirms the electrical connections, sets up the thermostat, checks the condensate drain and float switch, and runs the system long enough to record temperatures and pressures. You receive a walk-through of the new equipment, filter locations and maintenance schedule, and the old equipment leaves with the crew.
Common air conditioner replacement mistakes
Most disappointing new systems trace back to one of these decisions.
Matching the old tonnage by default
The original system may never have been sized correctly, and insulation or window upgrades since then change the load. A load calculation often shows a different size is right.
Replacing only the outdoor unit
Pairing a new condenser with an old coil can reduce efficiency, cause refrigerant compatibility problems and void manufacturer warranties. The outdoor and indoor sections are designed as a matched set.
Skipping the vacuum step
Moisture and air left in the lines damage compressors and reduce capacity. A deep evacuation verified with a micron gauge is not optional, even when an installer is in a hurry.
Ignoring the duct system
A new air conditioner cannot deliver its rated capacity through ducts that are too small or leaky. Static pressure testing before installation shows whether changes are needed.
Choosing on price alone
The lowest bid often excludes line set replacement, pad, permit or thermostat. Compare the full scope, not just the total.
Variables that move an installation quote
- Capacity and efficiency tier
- Larger tonnage and higher SEER2 ratings cost more up front and less to run. The proposal shows both so you can compare the payback.
- Condition of the existing line set
- A line set that is the wrong size, damaged or incompatible with the new refrigerant may need replacement, especially if it runs through finished walls.
- Electrical and drainage updates
- A new disconnect, a larger breaker, a condensate pump or a secondary drain pan may be needed to meet code and the manufacturer's requirements.
- Indoor coil and furnace match
- The indoor coil must be matched to the condenser and must fit the furnace cabinet. An older furnace with a weak blower can limit the choices.
Air conditioner installation questions
- Can I replace just the outdoor unit?
- Sometimes, but it is rarely the best choice. The outdoor condenser and indoor coil are engineered as a matched pair. Mixing a new condenser with an old coil can reduce efficiency, void warranty coverage and, with newer refrigerants, may not be compatible at all.
- Why not just install the same size as before?
- The original unit may have been sized by rule of thumb, and the house may have changed since then with new windows, insulation or additions. A load calculation often shows a different size is correct, and oversizing causes humidity and short cycling problems.
- How long does an installation take?
- A straightforward replacement of a condenser and coil is usually completed in one day. Jobs that need a new line set through finished walls, electrical upgrades or duct modifications can take longer, and the proposal will say so.
- Do I need a permit?
- In most jurisdictions, yes. Replacing cooling equipment usually requires a mechanical permit and sometimes an electrical permit. We pull the permits that apply and schedule any required inspection.
- What maintenance does a new system need?
- Change or clean the filter on the schedule for your filter type, keep plants and debris a couple of feet away from the outdoor unit, and have the system checked once a year so the coil and drain stay clean.
Start with a measurement, not a sales pitch
Book an in-home evaluation and get a written proposal with matched equipment, model numbers and a flat installed price.