The right way starts with a load calculation and a duct assessment, not with picking equipment. Sizing and installation quality determine how a system performs far more than the brand or the efficiency rating on the box.

Step One: Confirm You Need to Replace

Before pricing anything, establish whether replacement is actually warranted.

Multiply the repair cost by the system’s age in years. If the result exceeds the price of a new system, replacement is usually the better decision. A single component failure on equipment under ten years old is a repair, not an end-of-life signal.

The exceptions that settle it: a cracked furnace heat exchanger, a failed compressor on an out-of-warranty system past twelve years, or obsolete R-22 refrigerant where a leak means a recharge costing a meaningful fraction of a new system.

Step Two: Get a Load Calculation

The most consequential decision is capacity, and the most common shortcut is matching the tonnage of what is already installed.

That perpetuates whatever mistake was made originally, and in this region the usual mistake is oversizing. An oversized system cools quickly, shuts off, and never runs long enough to remove humidity — so the house reaches 73 degrees and still feels clammy. It also short cycles, which wears out compressors.

A proper calculation uses square footage and volume, insulation levels, window area and orientation, shading, air infiltration, and construction type. Hill Country housing stock varies enormously, and a 1920s limestone house and a 2015 build are not comparable.

Step Three: Assess the Ductwork

New equipment cannot outperform the duct system it feeds, and high-efficiency variable-speed gear is more sensitive to duct problems, not less.

Undersized returns force the blower against static pressure it was never designed for. Supply ducts leaking into a 140 degree attic deliver conditioned air to a space you do not live in.

We measure static pressure and inspect the ductwork before quoting. Sometimes the honest recommendation is duct sealing plus mid-tier equipment rather than a premium system on compromised ducts — and that is the smaller invoice.

Step Four: Choose the System Type

Before defaulting to like-for-like, consider whether a different configuration suits your house better.

Our cooling season runs roughly seven months and winters are short and mild — a profile that favours a heat pump, which handles both jobs from one system. A hybrid fuel system pairs one with a gas furnace and switches automatically, which suits homes that already have gas.

For a room the central system never reached, a ductless mini split is usually cheaper and more effective than upsizing the whole house.

Step Five: Choose an Efficiency Tier Honestly

Higher efficiency costs more upfront and less to operate. In a climate with this many runtime hours, the payback math often works — but it depends on what you are replacing.

Moving from a fifteen-year-old single-stage system to modern variable-speed equipment is a large jump. Moving from a five-year-old mid-tier system is not.

The comfort argument is often stronger than the efficiency one. Variable-speed systems run longer at lower output, removing far more humidity — and in a Texas summer that is what determines whether a house feels comfortable.

Step Six: Insist on Commissioning

This is the step most often skipped and the one that determines whether you get what you paid for.

Refrigerant lines must be evacuated to a deep vacuum before charging — skipping it leaves moisture in the system, which forms acid and shortens compressor life invisibly. Charge is set by weight to specification and verified under operating conditions. Airflow is measured. Controls are configured for the actual equipment staging.

An installation that finishes suspiciously fast has skipped some of this.

Comparing Quotes

Be cautious with a bid dramatically below the others. It is usually lower because something was excluded — permits, duct corrections, commissioning, or removal and disposal.

Ask how they size, what commissioning includes, and whether permits are in the price.

Details are on our AC replacements and installation pages. Financing is available.

Contact 72 Degrees or call (830) 240-1835.