Free HVAC inspection checklist: nameplate capture, readings with targets, condition grade and report

Published September 5, 2026 · Checked against ACCA 4 QM, the ASHI and InterNACHI standards of practice, EPA Section 608 and HVAC School's field references, September 2026

• Free. The files come by email.
• Deepsel is our product. It's free estimate, invoice and scheduling software for contractors (scheduling, quotes, invoicing, card payments, with service plans on the $29 Pro plan), and the section before the FAQ says where this inspection fits in it.
• The checklist doesn't replace the manufacturer's service instructions or your safety training. Targets on it are field references, and the data plate wins wherever the two disagree.

An HVAC inspection checklist records what a tune-up doesn't: the data plate for every unit (make, model, serial, age, capacity, refrigerant, filter sizes), safety checks with CO limits, cooling and heating readings against printed target ranges, static pressure, a five-point condition grade, and a findings table that marks pre-existing problems. This one is free, prints on three pages per unit, and copies into Google Docs.

Get it three ways: make your own copy in Google Docs (lands in your Drive), download the Word version (.docx), or download the PDF. Pick a format, enter your email and I'll send the links. Every section is reproduced on this page below, so you can read it before you print it. The maintenance and tune-up versions, plus a matching equipment log, are on the free HVAC checklists page.

I built this one because the inspection checklists that rank for this search are lists of "check the capacitor" lines with nowhere to write the microfarads. A checkmark next to "capacitor" is worth nothing in a dispute six months later. The reading is. So every line here has a blank for the number and the target it should land inside.

What is an HVAC inspection, and how is it different from a tune-up?

An HVAC inspection looks, measures and records. The technician photographs the data plates, runs the system, takes readings, grades the condition of each unit and writes up what needs attention. Nothing gets cleaned, adjusted or added. A tune-up does the work: coils, drain, filter, connections, settings. Maintenance is the tune-up repeated on a schedule under an agreement. Inspect first, quote from the findings, then maintain.

That separation is the whole point of the sheet. When a tech adjusts things during an inspection, the report describes a system that no longer exists. One thread on r/hvacadvice shows the mess this makes. A buyer's home inspector measured a 10-degree split on a 2008 Lennox and called it end of life. The seller's HVAC company came out, "added refrigerant," and reported a 23-degree split and five to seven more years.⁴ Both reports were true on the day they were written. Neither one told the buyer the thing that mattered, which the top comment did: "The tech added refrigerant meaning it was down on charge. Did they find a leak? Did they repair a leak?"⁴ An inspection sheet with a "suspected leak" box and a rule against adding anything would have said so.

Two more things an inspection is not. It isn't a home inspection: both national home-inspector standards say the inspector operates the system with normal controls and describes it, and is not required to inspect heat exchangers or the inside of flues,² or to "determine the uniformity, temperature, flow, balance, distribution, size, capacity, BTU, or supply adequacy of the heating system."³ As one HVAC tech put it in that same thread, "Home inspectors typically are not certified HVAC technicians. They just check it to see if it's cooling or not."⁴ And it isn't the ACCA maintenance standard either. ACCA 4 QM, reaffirmed by ANSI in 2024, is the "manufacturer-endorsed set of minimum tasks that should be performed for HVACR equipment maintenance inspections,"¹ and it covers the doing. If you want the doing, take the HVAC maintenance checklist or the tune-up checklist instead. This page is the looking.

What should an HVAC inspection checklist include?

A header block and eight sections, one sheet per unit: the reason for the visit, then nameplate capture, safety, cooling readings, heating readings, airflow and ducts, a condition grade, findings with photos and pre-existing flags, and an age note with signatures. The order matters. Safety comes before readings because a CO reading over the limit ends the visit. Here is each section as it prints, with the reasoning.

1. Nameplate capture, photographed before anything is written

The first instruction on the sheet is to photograph both data plates. Then the fields: type, make, model, serial, manufacture date and age, capacity, refrigerant and factory charge, plate electrical (voltage, MCA, MOP) next to the breaker actually installed, filter nominal and actual size, UV bulb type, thermostat. The columns match Section 1 of the HVAC maintenance agreement template and the equipment columns of the tracking spreadsheet on purpose. One inspection fills all three.

2. Safety, done first

Seven lines, and a Fail on any of them stops the inspection until it's reported. The carbon monoxide line has two readings: ambient air at the unit and at a supply register. Homes without gas stoves normally sit between 0.5 and 5 ppm;¹⁶ the sheet says investigate above 9 and leave and report above 35, which is the NIOSH eight-hour limit (OSHA's is 50).¹⁶ If you carry a combustion analyzer, the flue line records CO air free and O2: the ANSI Z21.47 certification ceiling for a gas furnace is 400 ppm air free, and field practice treats 100 ppm as the point to stop and investigate.¹⁵ HVAC School's furnace guide draws the same two lines: under 100 is the target, and past 400 "you are required to shut down the furnace."¹¹ Between them, 100 to 400 or a reading that keeps climbing, the job is to find the cause before leaving; over 400, the furnace stays off until it is repaired.

Then the gas leak sweep at the valve, unions, flex connector and drip leg with a combustible gas detector, and a bubble test on any hit,¹¹ the venting, the burner flame and rollout, the visible surfaces of the heat exchanger (the sheet says out loud that a full inspection needs a scope), the disconnect and wiring, condensate protection, combustion air, and whether the house has a CO alarm at all.

3. Cooling readings, with the system running ten minutes

Every reading has a blank and a target. The one people argue about most is the temperature split, so the sheet prints the honest version: about 18 to 22 degrees, and only at 45 to 55 percent return-air humidity. HVAC School's article on the "20-degree rule" runs the psychrometrics and shows the rule holding at 72 degrees and 45 percent humidity, then falling apart at 80 degrees and mid-60s humidity, which is exactly what a house looks like after the system has been off all day.⁹ That's why the line above it asks for return dry bulb, wet bulb and humidity. A low split is a finding, not a diagnosis, and the sheet says so in print.

The capacitor line reads "within the label tolerance, usually ±6%" because 6 is what Genteq, the usual OEM brand, prints on the can (Titan Pro and AmRad print ±5%);²⁹ HVAC School's testing guide says outside that range "replacement of the capacitor may be necessary," and then tells you to double-check the math before you quote it.¹⁰ The refrigerant line is deliberately non-invasive first. Line temperatures and a split tell you whether the charge is in question. Gauges go on only when it is, and only in the hands of someone with an EPA Section 608 certification, which the rules require for anyone who could release refrigerant.¹⁷ When gauges do go on, the HVAC troubleshooting chart matches the pressures, superheat and subcooling to the fault that usually produces them. If something was added, the sheet has no place to hide it.

4. Heating readings

Temperature rise is the heating reading that predicts the most trouble, and the sheet asks for the plate range beside it because every furnace is different. HVAC School's guide to the measurement puts it plainly: mind the high end of the range, because a rise near the top means the furnace is cycling on its limit and overheating the heat exchanger, and the cause is airflow, so look at the filter, the blower wheel and the static pressure.¹² The flame sensor target of 1 to 10 microamps, preferably 2 to 6, comes from the same site's furnace reference.¹¹ A furnace-specific version of these lines, with the cleaning steps included, is in the furnace maintenance checklist, and heat pumps get their own treatment in the heat pump maintenance checklist.

5. Airflow and ducts

Total external static pressure, return and supply, against the plate maximum. Most residential equipment is rated at 0.5 inches of water column,¹³ and a return-side reading of 0.4 or more is high on its own, usually a dirty filter or an undersized return.¹⁴ Then the filter as found (clean, dirty, collapsed, missing, wrong size), visible duct damage and leaks at the plenum, a count of returns and supplies, and a thermostat check against a reference thermometer.

6. The condition grade

A grade forces a verdict. Property condition assessments under ASTM E2018 use "good, fair and poor,"²⁶ and Housecall Pro's own inspection template suggests Pass, Flag and Fail per line.²⁷ The sheet uses both: Pass, Flag or Fail on each line, then a five-point grade per unit that maps back to good, fair and poor so a property manager can drop it straight into a portfolio report.

7. Findings, photos and the pre-existing column

Each finding gets a line: what, where, the reading, a priority (Safety, Now, Watch), a photo number, an estimate, and a box that says "Excluded." That last box is the reason a maintenance shop should inspect before it signs anyone up. An r/HVAC contractor who was asked how to price maintenance on a site with eleven mini-split heads gave the procedure in three sentences: "Do an initial 'as found' inspection and list all the pre-existing problems. Quote those repairs as a sum total... As you get the site to an 'only maintenance needed' condition... you'll then know how to quote a maintenance inspection cost. Always repairs are extra."⁶

The written record also settles who pays later. A first-time buyer in Arizona closed on a house in July 2025 and the compressor died the same day. The home-warranty company called it pre-existing and left them with $3,035 of a $3,110 repair, until, in their words, "I was able to provide my home inspection showing it didn't exist prior."⁷ A dated sheet with readings on it is that document. A checkmark isn't.

The three inspections a small shop actually does

The same sheet serves three visits, and the "Reason" line at the top is there so the file tells you which one it was.

The first visit on a new maintenance agreement. This is the one that matters to a shop selling plans. Section 1 fills the agreement's equipment schedule and the tracking spreadsheet. Section 7's Excluded column documents what the plan will not cover until it's fixed, and Section 8's acknowledgement has the customer sign that those conditions existed on that date. Skip this visit and every later breakdown becomes an argument about whether the plan should have caught it.

The home-sale inspection. Buyers arrive here holding a home-inspector report that says "end of life" and an agent who says they cannot ask for money on something that works.⁵ What they need is a document with numbers on it. Age from the serial, the split with humidity next to it, static pressure, capacitor readings, a CO number, and the leak box either ticked or not. The r/hvacadvice thread from February 2026 is the whole conversation in one comment: "15-18 is about what you should expect to get out of it, although it may go longer. Can't really predict how long it will last, that's why they generally go based off of age."⁵ A sheet that records age and condition separately lets the buyer make that call instead of the tech.

The landlord or property-manager walk-through. One sheet per unit, a condition grade per unit, and the grades roll up into a portfolio table by building. Property managers already think in good, fair and poor,²⁶ which is why the five-point grade maps onto those three words. Run it seasonally, and the grades become a replacement schedule instead of a string of emergency calls. The commercial HVAC maintenance checklist covers the rooftop-unit version of this visit, and the preventive maintenance schedule template is where the roll-up lives.

How old is the unit? Reading the serial number

Section 1 asks for manufacture date and age, and most of the time the plate does not say. The serial does, brand by brand. The rules below are from HVAC Base's decoder and Ray Franco's date-code reference,^{24, 25} and the first instruction on both is the one on the sheet: photograph the entire plate first, because the model number reveals size and refrigerant and the serial reveals the date.

Then the replacement math, which the sheet does in one line. ASHRAE's equipment life chart puts the median at 15 years for a residential split air conditioner or air-to-air heat pump and 18 for a gas or oil furnace.²¹ ENERGY STAR tells homeowners to start considering replacement when a heat pump or AC passes 10 years and a furnace or boiler passes 15.²² The $5,000 rule that homeowners bring to the kitchen table multiplies age by the repair quote and points at replacement above $5,000.²³ The sheet prints all three next to each other so the customer sees the same numbers you do. Age alone is a weak predictor, and the Houston tech who runs an annual contest with a coworker for the oldest working condenser (this year's winner was 26 years old, "out of 1000's of condensers") would tell you 12 to 14 is where the major failures start showing up in his market.⁴

Refrigerant belongs in the same conversation, so it's on the same line. R-22 stopped being produced or imported in 2020.¹⁸ New residential air conditioners and heat pumps have had a 700 GWP limit since January 1, 2025, which ended R-410A in new equipment;¹⁹ a May 2026 EPA rule lets contractors keep installing the R-410A units built before that date until supplies run out, except in New York, which kept its January 2026 cutoff.²⁰ An R-22 system with a leak and a 2005 serial is a replacement quote, and the sheet should make that obvious before anyone prices a compressor.

What the tech writes down, and why the numbers matter more than the checkmarks

Every competing inspection checklist I read has a line for the capacitor. Almost none has a blank for the microfarads, the rating, and the tolerance. That difference decides what the sheet is worth later. "Checked capacitor" is a claim. "Herm 42.1 of 45 rated, 6.4 percent low" is evidence, and it tells the next tech, the customer, and if it comes to it the customer's lawyer, exactly what was true on that date.

The same goes for the split. A temperature split written down without the return humidity beside it is the number the seller's tech and the buyer's inspector fought over in that r/hvacadvice thread, 10 degrees against 23, with a refrigerant top-off in between that nobody explained.⁴ Written with humidity and outdoor temperature beside it, the split is a data point. Written with the words "nothing added," it's a defensible one.

Photos are the other half. The owner-operators who answered a question on r/HVAC about how they handle paperwork after going independent agreed on what the photos are for: "The 90% is just nameplates and data tags."⁸ The sheet's photo line lists eight shots, and the findings table has a photo-number column so each finding points at its picture. Do it before leaving the driveway. The tech who said "on spot or it'll never be on there" was describing every shop I've read about.⁸

One more habit the sheet enforces: the tech's signature and license number go next to the customer's. An inspection report is a professional opinion, and a signed one is worth more to a buyer, a landlord and a warranty company than an unsigned checklist from an app. I tell the owner the same thing on what to ask your HVAC technician: keep the dated sheet with the license number, the readings and the photos.

After the visit: where the sheet's data goes

Section 1 of this checklist, make, model, serial, capacity, refrigerant and filter size off both data plates, is the equipment record in Deepsel, our free estimate, invoice and scheduling software for contractors, and the tech captures it from the nameplate photo on the phone. The readings with their target ranges fit a checklist template you build once: the tech fills it in on the visit from the phone, a reading outside its range gets flagged, and the condition grade is a pick list. It all stays on the job with the photos, so the next inspector can pull up these numbers there. Deepsel doesn't chart them on the equipment record yet. The repairs in the findings table become a quote on the same job, and the visit is invoiced and paid by card in the driveway, whether it was a home sale, a landlord walk-through or the first visit on a new plan. All of that is on the Free plan: scheduling and dispatch, quotes, invoicing, card payments, and customer and equipment records, with 30 estimates and 30 invoices a month for your whole team.

If the inspection turns into a signed plan, the service plans module on Pro ($29 a month, unlimited users, estimates and invoices) keeps visits owed against visits delivered per covered unit, renews the card on file, and sends the season booking reminders by email, so the next visit the report promised gets booked and logged against the plan in the same place the inspection was dispatched from.

Step one costs nothing. Run the shop on Deepsel Free, no card to start, and keep the agreement book beside it in the free maintenance agreement tracking spreadsheet: one row per agreement, the same equipment and filter columns as Section 1, visits owed and delivered, days to renewal. The contract itself is the free HVAC maintenance agreement template, whose Section 1 equipment schedule and Section 9 pre-existing exclusions are what Sections 1 and 7 of this checklist feed. If you stay on paper, the equipment maintenance log template is where each unit's inspection history stacks up visit after visit, and how to track HVAC maintenance agreements explains the sheet column by column. A sheet holds a small book fine. You outgrow the pair when the shop sends more than 30 estimates or 30 invoices a month, or the sheet's hand-work (reminders, renewals, visits owed) starts eating the office's week. Then move up to Pro: the sheet's customers import in one upload, and each plan is set up once in the service plans module.

Frequently asked questions

What is the difference between an HVAC inspection and a tune-up?

An inspection looks, measures and records. The tech photographs the data plates, takes readings with the system running, grades the condition and writes up findings, and touches nothing. A tune-up (or maintenance visit) does the work: cleans the coils and drain, replaces the filter, tightens connections and adjusts what is out of range. Most shops inspect first and quote repairs from the findings, then maintain on a schedule. The maintenance version of this sheet is the HVAC maintenance checklist.

Does a home inspector check the furnace and air conditioner?

Only from the outside. Both national home-inspector standards say the inspector operates the system with normal controls and describes it, and is not required to inspect heat exchangers, the inside of flues, or the capacity and supply adequacy of the equipment. No gauges, no combustion analyzer, no serial-number age check unless the inspector chooses to. That is why a buyer who gets an end-of-life note on the report should book an HVAC inspection before closing.

How do I find the age of an HVAC unit from the serial number?

Read the data plate on the outdoor unit or inside the furnace cabinet. Goodman, Amana and Daikin serials start with the year and month (YYMM). Carrier, Bryant and Payne start with the week, then the year. Rheem and Ruud put the week and then the year in the two-digit pairs right after the plant letter. Lennox prints the manufacture date on the plate in plain text, so skip the serial. Photograph the whole plate before decoding anything; the model number gives capacity and refrigerant, the serial gives the date.

What temperature split should an air conditioner have?

About 18 to 22 degrees Fahrenheit between return and supply air, and only when the return air is near 45 to 55 percent relative humidity. In a humid house that has been off for hours, a healthy system can read 12 to 15 degrees while it wrings the moisture out. So a low split by itself is a finding to write down and follow up on, not a diagnosis. Record return dry bulb, wet bulb and humidity next to it and the number means something.

Can a technician add refrigerant during an inspection?

They can, and they should not. Refrigerant does not get used up; a system that is low has a leak, and adding gas hides the evidence the customer is paying you to find. Write the readings down, mark the circuit as a suspected leak, and quote the leak search as a repair. Anyone who opens the circuit needs an EPA Section 608 certification, and any refrigerant added or recovered should be noted on the report by type and amount.

What is the $5,000 rule for HVAC?

Multiply the system's age in years by the repair quote. Over $5,000, replacement is usually the better long-term move; under it, repair. A 12-year-old condenser with a $500 capacitor-and-contactor repair scores $6,000, which points at replacement, although most owners would take that repair and start saving. The rule is a conversation opener, not a verdict. Section 8 of the checklist has a line for the math.

Sources

1. ACCA, "ACCA announces ANSI approval for reaffirmation of ACCA 4 QM - 2019 (R2024), Maintenance of Residential HVAC Systems" - "a nationally recognized, manufacturer-endorsed set of minimum tasks that should be performed for HVACR equipment maintenance inspections." acca.org, September 16, 2024, read September 5, 2026.
2. American Society of Home Inspectors, Standard of Practice, Section 8 Heating - "The inspector is NOT required to: Inspect: Interiors of vent systems, flues, and chimneys that are not readily accessible. Heat exchangers." homeinspector.org, 2026 edition, read September 5, 2026.
3. InterNACHI, Residential Standards of Practice, Section 3.4 Heating - the inspector is not required to "inspect, measure, or evaluate the interior of flues or chimneys, fire chambers, heat exchangers" or "determine the uniformity, temperature, flow, balance, distribution, size, capacity, BTU, or supply adequacy of the heating system." nachi.org, read September 5, 2026.
4. r/hvacadvice, "Home Inspector Said HVAC Near End of Life and Seller's HVAC Guy Disagreed." - inspector: return 66.4, supply 57.4, "AC is cooling across the coil by 10 degrees. Standard is 15-20 degrees"; seller's tech "added refrigerant" and reported 72.5 return, 49.5 supply. Top comment: "The tech added refrigerant meaning it was down on charge. Did they find a leak? Did they repair a leak?" Also "Home inspectors typically are not certified HVAC technicians. They just check it to see if it's cooling or not" and, from a Houston tech, "12-14 is reaching an age that we see major failures... This years winner was 26 years old... out of 1000's of condensers." reddit.com, October 20, 2024, read September 5, 2026.
5. r/hvacadvice, "Buying a home with a 15 year old hvac. How long will it last?" - "The realtor said we can't ask for a deduction on something that is working. The inspector said it's at the end of its life"; top comment: "15-18 is about what you should expect to get out of it, although it may go longer. Can't really predict how long it will last, that's why they generally go based off of age." reddit.com, February 7, 2026, read September 5, 2026.
6. r/HVAC, "Maintenance, how much should I be charging" - "Do an initial 'as found' inspection and list all the pre-existing problems. Quote those repairs as a sum total... Always repairs are extra." reddit.com, December 11, 2024, read September 5, 2026.
7. r/hvacadvice, "Closed on my home on 7/11, compressor went out same day" - "My out of pocket would be $3035 because they claim it's a preexisting condition. I was able to provide my home inspection showing it didn't exist prior." reddit.com, July 22, 2025, read September 5, 2026.
8. r/HVAC, "Techs who went independent, how do you handle the..." (post since removed by moderators; comments live) - "I try to put serial number pictures on the customer account. - On spot or it'll never be on there" and "The 90% is just nameplates and data tags." reddit.com, April 15, 2026, read September 5, 2026.
9. HVAC School, "20° ΔT (Delta T), A Lazy Rule of Thumb" - "depending on who you ask, the answer will range between 18-22 degrees Fahrenheit"; the rule holds at 72 °F and 45% RH and is "busted" at 80 °F with humidity in the mid-60s. hvacrschool.com, read September 5, 2026.
10. HVAC School, "Testing Run Capacitors the Smart (and Easy) Way" - "Most capacitors allow for a 6%+/- tolerance. If it's outside of that range, then replacement of the capacitor may be necessary. Always double-check your math before you quote a customer." hvacrschool.com, read September 5, 2026.
11. HVAC School, "Gas Furnaces - What a Tech Needs to Know" - flame sensor "between 1 and 10 microamps, preferably between 2 and 6"; nameplate heat rise "usually something like 45-65°F"; manifold pressure "often 3.5" WC (for a range of 3.2-3.8" WC)"; "400 PPM is the maximum allowable concentration of CO air free in the flue. If you have 400 PPM or above, you are required to shut down the furnace. Below 100 PPM is the recommended CO air free target"; gas leaks: "use a combustible gas leak detector... apply a leak reactant and look for bubbles." hvacrschool.com, read September 5, 2026.
12. HVAC School, "Furnace Air Temperature Rise" - "Every gas furnace data plate/tag has a specification for the temperature rise through that furnace. It is shown in a range like 50-80° or 45-75°"; "It's more important that we mind the high end of the rated range... the furnace may begin cycling on the limit control." hvacrschool.com, read September 5, 2026.
13. HVAC School, "Air Filter Static Pressure Drop" - "With most systems being rated at 0.5″wc TESP (total external static pressure), that filter makes up more than half of that number." hvacrschool.com, read September 5, 2026.
14. HVAC School, "Total External Static Pressure (TESP): A Basic Review" - "A high return static reading (typically 0.4in w.c. and above) can be caused by dirty filters or undersized ductwork." hvacrschool.com, read September 5, 2026.
15. HVAC Know It All, "Combustion Analysis: A Thinking Tech's Guide" - "the National Comfort Institute (NCI) uses 100 ppm as-measured as their best-practice max. The ANSI Z21.47 standard allows up to 400 ppm air-free for vented equipment... Above 400 ppm air-free requires immediate shutdown." hvacknowitall.com, read September 5, 2026.
16. U.S. EPA, "Carbon Monoxide's Impact on Indoor Air Quality" - "Average levels in homes without gas stoves vary from 0.5 to 5 parts per million (ppm)"; OSHA PEL 50 ppm eight-hour TWA; NIOSH REL 35 ppm eight-hour TWA. epa.gov, read September 5, 2026.
17. U.S. EPA, "Section 608 Technician Certification Requirements" - "technicians who maintain, service, repair, or dispose of equipment that could release refrigerants into the atmosphere must be certified." epa.gov, read September 5, 2026.
18. U.S. EPA, "Phaseout of Class II Ozone-Depleting Substances" - phaseout table: "2020: No production or import of HCFC-142b and HCFC-22." epa.gov, read September 5, 2026.
19. U.S. EPA, "Technology Transitions HFC Restrictions by Sector" - stationary residential and light commercial air conditioning and heat pumps: GWP limit 700, compliance date January 1, 2025. epa.gov, read September 5, 2026.
20. U.S. EPA, final rule, 91 FR 31284 (FR Doc. 2026-10387, RIN 2060-AW39), May 26, 2026 - revised 40 CFR 84.54(c)(1): new residential and light commercial air-conditioning and heat pump systems at 700 GWP or more "may continue to be installed where all specified components of that system are manufactured or imported prior to January 1, 2025"; the summary says the rule "Removes the installation deadline"; "This final rule is effective on July 27, 2026." govinfo.gov, read September 24, 2026. Reported by the National Association of Home Builders, "EPA Finalizes Refrigerant Rule Update to Allow Older HVAC Unit Installation," nahb.org, May 26, 2026, read September 24, 2026. New York: NYSDEC, Part 494 FAQ, May 2026 - "USEPA later extended the prohibition one additional year to January 1, 2026 … Part 494 adopted the later date for all products and systems." dec.ny.gov, read September 24, 2026.
21. ASHRAE Equipment Life Expectancy chart (median years) - air conditioners, residential single or split: 15; heat pumps, residential air-to-air: 15; furnaces, gas- or oil-fired: 18. naturalhandyman.com (PDF), read September 5, 2026.
22. ENERGY STAR, "When is it time to replace?" - "Your heat pump or air conditioner is more than 10 years old... Your furnace or boiler is more than 15 years old." energystar.gov, read September 5, 2026.
23. CBS News, "What is the $5,000 rule for HVAC systems?" - "The age of your HVAC system x the estimated repair cost... If the result of that formula is more than $5,000, a replacement is often considered the better long-term option." cbsnews.com, June 24, 2026, read September 5, 2026.
24. HVAC Base, "HVAC Serial Number Decoder: Find Age of Any Brand" - "Take a photo of the entire data plate"; Carrier/Bryant/Payne "1st-2nd: Week of manufacture, 3rd-4th: Year"; Goodman/Amana/Daikin "First four digits = YYMM"; Lennox "look for the manufacture date printed on the data plate"; "024=2 ton, 036=3 ton, 048=4 ton, 060=5 ton." hvacbase.org, read September 5, 2026.
25. Dr. Ray Franco, PE, "Air Conditioner Date Codes" - Goodman "SN: 0606111539 was manufactured in 2006, June"; ICP "The first pair of numbers is the year, and the second pair of numbers is the week... SN: E031136011 was Manufactured in 2003, Week 11." electrical-forensics.com, read September 5, 2026.
26. NV5, "ASTM E2018 Standards for Property Condition Assessments" - physical condition opinions "commonly employ terms such as good, fair and poor." nv5.com, read September 5, 2026.
27. Housecall Pro Help Center, "Checklist Templates for HVAC" - Inspection Checklist: "Use Pass/Flag/Fail to make it easy for technicians to assess if in good condition, needs attention, or needs repair/replacement." help.housecallpro.com, January 21, 2026, read September 5, 2026.
28. ServiceTitan, "HVAC Inspection Checklist Template: Free PDF Download" - "To get your free template, fill out our form... and we'll email it to you straightaway." servicetitan.com, read September 5, 2026.
29. Genteq (Regal), capacitor catalog GTC-02/10 - "Capacitance Tolerance: ±6%"; the label diagram lists "Tolerance" as a printed field. pdf.product.network. Titan Pro spec sheet, "Capacitance Tolerance … ±5%," totalhomesupply.com. Both read September 24, 2026.
30. Rheem, "What to Know Before Meeting with an HVAC Contractor" - "The first two numbers after the letter in the middle or beginning of the serial number are the week of manufacture, and the third and fourth numbers are the year of manufacture." rheem.com. Building Center, "Rheem HVAC Age" - style 1 "W 29 10 13412"; styles 3 and 4 put the plant letter (F, M, G, W, N) in the middle; style 5 "08 04 B10488," month then year. building-center.org. Both read September 24, 2026.
31. Trane Commercial Help Center, "How to read a Light Commercial Unit Serial Number Date Code" - year codes "1999 P 2000 R 2001 Z 2002 2 … 2009 9 2010 10." support.trane.com. Building Center, "Trane HVAC Age" - the 1983 to 2001 style "beginning with a letter followed by 2 digits"; the 2002 to 2009 and 2010-on styles; "The MFR Date is commonly included on the data rating plate." building-center.org. Both read September 24, 2026.