FairReplace

How we estimate

Everything on FairReplace comes from public data and written-down rules. This page shows the rules, the sources and the places where the numbers are weakest.

Ages from serial numbers

Each brand's date code is stored as data: the pattern, which characters hold the year, month or week, and the years each format was in use. We cover 36 brands in 15 serial systems. We tested the rules against 212 serials; 103 of them have a date known without the rule (a recall notice that lists serials with build dates, a manufacture date printed on the label, or the manufacturer's own statement). The rest are published worked examples. No rule produced a wrong year on that set.

Two things limit any decoder. Some codes reuse the same year letter every 20 or 21 years (Bradford White, the York family), so a serial can fit two decades; we show every reading, most recent first. And makers change formats; a serial in a format we haven't seen gets "we couldn't read this" rather than a guess.

Official format means the manufacturer publishes how its serials encode the date. Widely documented means it doesn't, and the rule comes from recall notices, service literature and inspector references. Brands we couldn't test are not listed: Nordyne / Nortek brands (Frigidaire, Maytag, Gibson, Tappan, Intertherm, Miller, Broan, Westinghouse); Noritz; Takagi; GE water heaters; Kenmore water heaters; Lochinvar; Peerless; Burnham; Guardian, Champion; Mitsubishi Electric, Fujitsu.

Replacement prices

For each system and size, the installed price is equipment + installation:

  • Equipment: online list prices recorded on October 13, 2026 from retailers that show prices publicly (hvacdirect.com, alpinehomeair.com, supplyhouse.com). Low, typical and high are the 25th percentile, median and highest listing for that size. Big-box store prices and dealer-only brands (which don't publish prices) are not in the sample, so the high end can understate a dealer-brand quote.
  • Installation: the Department of Energy's average installation cost from the technical support document behind each efficiency standard (labor, materials, removal of the old unit and permits, averaged over the jobs DOE modeled), inflated to August 2026 with the Consumer Price Index (CPI-U, series CUUR0000SA0).
  • Local labor: the labor share of installation is scaled by the local trade wage relative to the national median (BLS Occupational Employment and Wage Statistics, May 2025: plumbers 47-2152 for water heaters and boilers, $31/hr national median; HVAC mechanics 49-9021 for furnaces, AC and heat pumps, $29/hr). The low and high estimates use the 25th and 75th percentile wages. The 50 largest metros use metro wages, other ZIP codes use statewide wages.
  • Billing markup: contractors bill far above wages. DOE's installation rates come from RSMeans and include overhead and profit (about 1.63 times a fully loaded rate); BLS employer-cost data put benefits at about 1.45 times wages; the 2022 Economic Census puts plumbing and HVAC contractors' receipts net of materials and subcontracts at 3.26 times their field workers' payroll. We use 2.4 times wage for a typical repair hour, 2.2 for the low estimate and 3.26 for the high.

Repairs (capacitors, igniters, anode rods and so on) are priced as the part's list price plus hands-on hours and a one-hour trip and diagnosis charge at that billed rate. Hands-on hours are our estimate of typical technician time; flat-rate price books vary.

Code extras (expansion tanks, drain pans, vent connectors, flue liners, condensate pumps) are shown separately. Vent costs come from DOE's furnace analysis (Table 8.2.10). Where a city publishes its permit fee, the metro page shows it.

Central AC and heat pump installation figures come from DOE's 2016 analysis, the newest available, and predate the 2025 refrigerant change. Treat them as a floor.

Repair or replace

The verdict compares the repair price divided by the years it is likely to buy (average life minus age, never less than 2 years) with a new unit's price divided by its average life. Under 0.75 of the new-unit figure we say repair, over 1.25 replace, in between a toss-up. A leaking tank and a confirmed cracked heat exchanger are replace calls regardless of the arithmetic. Average lives come from DOE's analyses (and ENERGY STAR for heat pump water heaters); AC and heat pump lives vary by climate.

Quote checks

Pasted quotes are read in your browser. We find the total, the system, the size and the line items, then compare the total with the local range plus the cost of any extras the quote includes. Bands: well below, below, typical (up to 12% over the typical figure), upper end, above our high, well above. When you choose to share a quote, we store the system, size, price, ZIP3 and which items were included. Area statistics appear only once five or more real quotes exist for that area and system. We never add made-up quotes.

What we don't do

  • We don't copy other cost guides' tables.
  • We don't name contractors next to prices.
  • We don't give repair steps for gas, burners, refrigerant or electrical work. Those are jobs for licensed pros.
  • We don't claim federal tax credits: 25C and 25D ended for equipment installed after December 31, 2025.

Found an error? Tell us. Corrections are dated on the page they affect.