Decision calculator

Repair your HVAC system or replace it?

Compare the repair path with replacing now. The model also accounts for a later replacement if the repaired system is not expected to last through the full comparison period.

Reviewed Oct. 1, 2026Model v6.1.5How our models work

HVAC condenser and diagnostic tools beside a home

This is a cost comparison, not a diagnosis.

Safety, refrigerant availability, comfort, reliability, system sizing, ductwork, and contractor findings can outweigh a small modeled cost difference.

Step 1

Quick comparison

Use your repair and replacement quotes plus a realistic estimate of how long the repair should extend the system's life.

Start here

Values shown are editable example defaults. Change them to match your situation.

Not sure what to enter? See how example defaults work →

Repair needed nowUse the written repair quote you are deciding whether to approve.

Replacement installed costUse the full installed quote before any incentives or credits.

Expected life after repairHow many additional years do you reasonably expect this repair to buy?

years

Compare overUse the same horizon for both paths.

years

Jump to current result ↓

Live resultUpdates automatically as you change the numbers

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Repair current system—

Replace now—

Repair path——

Replace now——

Estimated difference—

Repair breakeven——

What changes the answer?—

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How stable is this result?

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Stress test: a weaker repair case, the base case, and a stronger repair case.

See the math

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Test the decision

Move the two assumptions most likely to flip the result.

Repair needed now$2,500

Expected life after repair3 years

Quick estimate assumptions

Example operating-cost and maintenance assumptions are used until you replace them with your own numbers.

Annual energy: —Annual maintenance: —Incentives: —

Step 2 · optional

Advanced assumptions

Use your bills, quotes, and contractor estimates instead of the example defaults.

Show details

These are example assumptions, not national averages. Replace them when you have better local numbers.

Why these defaults? Source notes and assumptions · How defaults work

Current system after repair

Annual heating + cooling energy costUse your best estimate from utility bills. Count only the portion tied to HVAC if you can.

Annual maintenance + repair allowanceRoutine service plus a reasonable allowance for future repairs after today's repair.

Additional expected repairs during this periodA separate allowance for known or likely repairs beyond routine maintenance.

Replacement system

Annual heating + cooling energy costUse the contractor's estimate, equipment data, or your own modeled estimate.

Annual maintenance allowanceExpected routine service and minor repair allowance for the new system.

Rebates + tax credits you expect to receiveEnter only incentives you have verified for your equipment, location, and tax situation.

How to interpret the result →

Defaults are editableReplace example assumptions with your quotes, rates, and expected life.

Close calls stay closeScenario checks show when reasonable assumption changes can flip the result.

Math is visibleOpen “See the math” to audit the calculation structure.

When this calculator may not be enough

This model compares the financial paths you enter. Safety, code requirements, warranty coverage, reliability, downtime, financing constraints, and unusual installation conditions can outweigh a small modeled cost difference.

Did this help you make the decision?

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Try a worked example

Example: a repair that buys only a few years

Try a $2,000 repair that buys three more years versus a full replacement. The repair path will include a later replacement if the horizon is longer.

Edge case to stress-test

Test a short repaired life, high future repairs, or a large operating-cost gap. Those are the cases where replacement can become attractive quickly.

What's included

Today's repair, expected life after repair, replacement cost, incentives, operating costs, maintenance, expected additional repairs, and a delayed replacement when needed.

What's not

Financing, inflation, investment returns, exact failure probabilities, comfort differences, ductwork, indoor-air-quality upgrades, or a dollar value for reliability.

Best practice

Ask the contractor what else is likely to fail and how confident they are that the repair buys the years you entered.

Understand the comparison

These estimates are undiscounted: they do not model inflation, the time value of money, or every future failure. Monthly equivalents divide modeled cost across the period; they are not loan payments. Read the scope and exclusions for each model.

Resolve safety concerns with a qualified professional before comparing cost. Confirm quote scope, eligibility for incentives, and expected service life.