Air conditioner installation sized for how your home gains heat

A room-by-room cooling load calculation estimates how much heat enters the house on a design summer day through windows, walls, roofs and air leaks, plus the heat generated by people and appliances inside. Window orientation matters a great deal, since large west-facing glass can add substantial afternoon heat to a room.

The calculation also considers latent load, which is the moisture that must be removed to keep the home comfortable. An air conditioner sized only for temperature, and too large for the house, satisfies the thermostat quickly and shuts off before removing much humidity. The result feels cool but damp. Right-sized equipment runs longer, steadier cycles that handle both heat and moisture.

We compare the calculated load against the capacity of equipment options at your local conditions, not just the nominal tonnage printed in a brochure. That comparison guides a recommendation you can understand and question.

A split air conditioner has two main parts: the outdoor condensing unit and the indoor coil, which sits on top of a furnace or inside an air handler. These components are designed to work as a matched set. Pairing a new outdoor unit with an old coil can reduce efficiency, cause refrigerant control problems and complicate warranty coverage.

Refrigerant type is part of this decision. The industry is moving toward newer refrigerants with lower global warming potential, and equipment designed for one refrigerant generally cannot use another. Replacing the coil along with the outdoor unit usually makes sense for that reason alone.

Blower capacity matters too. The furnace or air handler must move enough air across the coil for the new system's capacity. When the existing blower is marginal or the ductwork is restrictive, the proposal will say so, and the fix may involve Ductwork Install And Replace before the new equipment can deliver its rated output.

Refrigerant lines connect the indoor and outdoor units. When new copper is brazed, the inside of the pipe can form oxide scale unless an inert gas such as dry nitrogen flows through it during brazing. That scale can later break loose and clog metering devices or damage the compressor, so our crews flow nitrogen during every brazed connection.

After brazing, the system is pressure tested to confirm there are no leaks. It is then evacuated with a vacuum pump to remove air and moisture, which would otherwise react with refrigerant and oil to form acids. The depth of the vacuum is confirmed with a micron gauge, and a decay test shows whether the system holds vacuum before refrigerant is released.

Existing line sets are evaluated rather than assumed reusable. Size, condition, routing and compatibility with the new refrigerant and oil all factor into whether they can stay or should be replaced.

The outdoor unit needs a level, stable base, clearance on all sides for airflow and room for technicians to service it later. We avoid spots where dryer vents, shrubs or roof runoff will affect performance, and we consider noise near bedrooms, patios and neighboring homes.

Electrical work includes confirming the circuit size and disconnect requirements specified by the manufacturer and local code. Loose or undersized connections can cause nuisance tripping or overheating, so terminations are tightened to specification.

Condensate drainage is easy to overlook. The indoor coil removes water from the air, and that water must drain reliably to an appropriate location. Traps, slope and safety switches are installed as required so a blocked drain shuts the system down rather than overflowing onto floors or ceilings.

Commissioning is the final and most important check. With the system running, the technician measures airflow or static pressure, refrigerant superheat or subcooling depending on the metering device, the temperature difference across the coil, and electrical current on major motors. These readings are compared with the manufacturer's installation data.

Adjustments are made until the readings fall within the expected range. Blower speed settings, refrigerant charge and thermostat configuration are all fine-tuned at this stage. The final numbers are written on a commissioning sheet that stays with you.

That record has lasting value. Future technicians can compare new readings with the originals to spot problems early, and the sheet documents that the installation was done to specification, which can be useful for warranty purposes.

Air conditioner quotes can look similar on the surface and differ greatly underneath. One may include a new indoor coil, a new line set, a pad, a disconnect, a condensate safety switch, a permit and commissioning, while another lists only the outdoor unit. Our proposals itemize the scope so you can compare them fairly against any other bid.

The equipment options are presented with their efficiency ratings, warranty terms and practical differences in comfort and noise. Single-stage equipment is the most economical. Two-stage and variable-capacity systems run longer at lower output, which improves humidity control and evens out temperatures, particularly in homes with a wide mix of sunny and shaded rooms.

Third-party financing is available subject to lender approval, and when we know of manufacturer or utility incentives that apply to a particular model, we point them out. The final price you approve is the price you pay for the scope listed, and any change to that scope is discussed with you in advance.