BTHE BARATELLI INSTITUTE · Mentoring at Scale
FOR HOMEOWNERS · LANDLORDS · PROPERTY MANAGERS · ANYONE STARING AT A REPAIR QUOTE

The furnace died. Repair it for $1,800, or replace it for $7,500. Run the math, then decide.

The 50% Rule: if repair quote is more than 50% of replacement AND age is more than 75% of useful life, replace. The NPV math: a 10-year discounted cash-flow comparing repair-and-wait against replace-now, factoring energy savings, future replacement timing, and financing cost. The honest answer that contractors selling replacements won't volunteer.

50% Rule
Repair vs cost
10-yr NPV
Both paths
Energy
Savings net of cost
Verdict
Clear answer
YOUR DECISION
1
Equipment
2
Quotes
3
Energy & usage
4
Timeline & financing
5
The decision
STAGE 1 OF 5

Equipment basics

Pick the item, enter the age. Useful life is built in as a benchmark; you can override.

Default by equipment type. Override based on brand, maintenance history, climate. AC + heat pump in coastal salt air = 12-15. Furnace well-maintained = 25-30. Tank water heater = 10-12.
1 = barely working, multiple repairs in last 2 years. 3 = average wear. 5 = lightly used, well maintained.
The 50% Rule (a.k.a. the contractor's secret). If a repair quote is more than 50% of replacement cost AND the equipment is more than 75% through its useful life, replace. If both aren't true, repair is usually the right call. This is the rule HVAC contractors apply to their own equipment but don't always recommend to customers — because the replacement is more profitable for them.
STAGE 2 OF 5

Repair quote vs replacement quote

The two numbers that drive everything. Get at least two quotes for each — HVAC and roof especially have wide quote spreads.

Total to fix and bring back to working order. Include any parts, labor, service call fee.
$
Total to replace with new equipment. Include removal, installation, permits, any electrical/gas work needed.
$
How many more years will the existing unit last after the repair? Be honest. Repairing a 20-year-old furnace usually buys 2-4 years, not 10.
Useful life of the new unit. Defaults to equipment type average; reduce for harsh climate or heavy use.
If you repair this time, what's the probability of another $1,000+ repair within 3 years? Older equipment = higher probability.
%
$
STAGE 3 OF 5

Energy & operating cost

Replacement is usually pitched on energy savings. Sometimes the savings are real (heat pumps, refrigerators); sometimes the payback is 20-30 years (windows). The math decides.

For HVAC and water heaters: the share of the utility bill attributable to that unit. For appliances: estimate $40-150/yr for most. For roof: $0 (no operating cost).
$
Realistic energy reduction the new unit delivers. Marketing literature inflates; real-world savings are usually 10-25% for HVAC, 5-15% for appliances, 0% for roof.
%
Historical rate ~3-5% in most markets. Higher for natural gas in winter regions; lower for stable electric.
%
Federal IRA credits (heat pumps up to $2K), state rebates, utility incentives. Reduces replace cost.
$
The energy-savings argument is overstated for some things, understated for others. Window replacement: typical 20-30 year payback (almost never pays for itself before the next replacement). Heat pump + insulation: often 3-7 year payback in cold climates with rebates. Tank-to-tankless water heater: 8-15 years (depends on hot-water usage). Old fridge to new ENERGY STAR: 4-8 years payback. Trust the math you put in here over the salesperson's pitch.
STAGE 4 OF 5

Household timeline & financing

How long you'll own the house changes the answer. Replacing in year 1 of a 10-year ownership is different from replacing in year 1 of a 30-year ownership.

The rate at which future dollars are discounted. Use your opportunity cost: HELOC rate if you'd otherwise pay debt, savings rate (~4-5%) if cash, 6-8% if comparing to S&P returns.
%
%
If it\'s actively broken (no heat in winter, no hot water), urgency overrides math. Tool will flag.
STAGE 5 OF 5

The decision

HERE — TRY THESE. THEY MAY HELP.

Repair-vs-replace is one of four flagship home tools.

The home-renovation cost estimator covers the bigger projects (kitchens, baths, roofs, additions). The kitchen and bathroom ROI tools cover the resale math. Or look at the guides — the Business Buyer's Guide is the operator framework, the Family Office Guide is the holding-and-estate framework.

Business Buyer's Guide Family Office Guide All free tools
This is not contractor, engineering, or financial advice. Materials and labor costs vary widely by region, season, contractor, and home condition. Get 3 written bids from licensed contractors and verify regional pricing before relying on any number. Equipment lifespan is an estimate; actual lifespan varies based on usage, maintenance, climate, and brand. This is not financial, tax, or legal advice.
HERE — TRY THESE. THEY MAY HELP.
Repair-vs-replace is a recurring question. The bigger picture sits in the guides.
If you\'re managing multiple properties, the Business Buyer\'s Guide covers maintenance economics for small portfolios. The Family Office Guide covers capital-budgeting discipline across a long-held real estate portfolio.
Business Buyer\'s Guide → Family Office Guide All free tools
PROFESSIONAL DISCLAIMER · PLEASE READ

Not contractor, engineering, or financial advice. Materials and labor costs vary widely by region, season, contractor, and home condition. Get 3 written bids from licensed contractors and verify regional pricing before relying on any number. Equipment lifespan is an estimate; actual lifespan varies based on usage, maintenance, climate, and brand quality.

NPV is an estimate. The 10-year discounted cash flow depends on energy inflation, discount rate, future repair probability, and equipment longevity — all uncertain. Use the math as one input, not as the answer.

Consult licensed professionals. Before acting on anything calculated here, consult licensed contractors, HVAC technicians, plumbers, electricians, and your financial advisor.

Educational references and tools — not legal, tax, accounting, or investment advice, and not a recommendation to buy or sell any security. Consult a qualified professional about your specific situation. © 2026 The Baratelli Institute.