Older furnace subjected to flooding (C) Daniel Friedman Find Age & Life Expectancy of Heating Boilers & Furnaces

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Age of heating equipment & Systems:

How to determine the age of your heating system and components. Here we provide several excellent sources for de-coding the data tag information on heating equipment.

This article provides documents that explain and translate all of the data found on information tags and stickers used on heating & heat pump equipment, including equipment age, heating capacity, electrical requirements, and operating characteristics.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Heating System Equipment Age - Guides for Reading HVAC & Water Heater Equipment Data Tags & Serial Numbers

Data tag from a Weil McLain gas boiler in Two Harbors MN (C) Daniel Friedman at  InspectApedia.comIf you don't know whether your heat is provided by a furnace (hot air) or boiler (hot water), or whether your fuel is oil, gas, or electric, and whether your heat is hot water, steam, or warm air, see HEATING SYSTEM TYPES. Then return to this page for help finding the equipment's age or date of manufacture.

Five HVAC Heating & Air Conditioning Equipment Age & Data Tag Decoders

Our photo shows data tags on a Weil McLain gas fired heating boiler that was manufactured on 10/10/1996. [Click to enlarge any image]

We found the boiler age by de-coding the boiler's CP/serial number code on the white sticker just above the data tag. Below we explain how we did that.

For help in decoding air conditioner, boiler, furnace, heat pump, water heater data tags and determining the age, model, or specifications of that equipment, see the following web pages:

  1. AGE of HEATERS, BOILERS, FURNACES - [you are here] general information about several ways to determine heating equipment age. Here we also discuss:

    AGE of a BUILDING or AGE of HEATER Age of the heating equipment can be estimaged by building age & equipment age an also indicate building age

    CARSON DUNLOP ASSOCIATES'' Technical Reference Guide DECODES DATA TAGS & AGE - information in this article about this for-purchase equipment age decoding book

    HVAC EQUIPMENT DATA TAG LOCATION in this article, where you can find manufacturer's name, model, and serial number. The age is encoded in most serial numbers.

    ONLINE HVAC EQUIPMENT DATA TAG DECODER - given in this article
  2. AGE of AIR CONDITIONERS & HEAT PUMPS - separate web page: how to de-code the serial number in the data tag to get cooling or heat pump equipment age
  3. AIR CONDITIONER BOILER FURNACE AGE, MANUALS & PARTS GUIDES - HVAC - separate web page: heating & air conditioning equipment age, history, manuals & manufacturer contact information sorted by individual brand name.

    This Master Index to All Brand Names & HVAC manuals, wiring diagrams, installation and repair guides for each furnace or boiler manual will get you to the manual for your boiler or furnace where that document will usually have specific furnace age or boiler age decoding information for the serial number or data tag that heater brand and model.
  4. AGE of WATER HEATERS There we provide documents with extensive equipment data tag decoding information for water heaters.
  5. Manufacturer websites: A few manufacturers offer free online boiler or furnace data tag decoders that give the equipment's age. We include links to any such websites we can find both here and in our ONLINE HVAC EQUIPMENT DATA TAG DECODER or AGE of AIR CONDITIONERS & HEAT PUMPS or MANUALS & PARTS GUIDES - HVAC pages that we listed just above.

    CONTACT us if you find a helpful manufacturer's site or data tag decoder that's not given in our four sources above.

Free Online HVAC Equipment Data Tag Decoders

We provide links to individual manufacturer's data tag decoding guides (Lennox, below), and to two excellent equipment data tag decoding books, by Scott LeMarr (online at this website) and the Carson Dunlop & Associates Ltd. Technical reference - the most extensive such document we've found.

For many heating or cooling equipment manufacturers, especially after 2000, decoding the equipment tag to obtain the age of the device is sometimes pretty easy.

Lennox pulse furnace data tag (C) Daniel Friedman

But equipment age, capacity, specifications are not always so easy to recognize on the data tag. Here we explain how to dig out that information.

[Click to enlarge any image]

1. Lennox HVAC products Age: see our LENNOX Heater & Air Conditioner Model & Serial Number Decoding Guide [PDF] at this website. Also see

2. FURNACE AGE DECODING CHART [PDF] provided by home inspector Scott LeMarr has generously shared his document that decodes both furnace age for many brands of water heater, including hot water systems produced by the following manufacturers.

[PDF linked to return here. You can also use the "BACK" button on your browser to return to this page at]

LeMarr's document provides decoding data for the following manufacturers:

Ambassador water heaters, American water heaters [3], ACE water heaters, A.O.Smith water heaters, Apollo, Aqua Temp, Aqua Therm, Best water heaters, Bosch water heaters, Bradford White, Cafos, Champion, Crosley, Energy Saver, Envirotemp water heaters, GE water heaters, Glascote water heaters, Golden Knight water heaters, GSW, Hotpoint water heaters, JC Penny, Jetglas, JW or John Wood, Kenmore water heaters (Sears Brand), Lochinvar, Lowes, Mainstream, Maytag water heaters, Montgomery Wards, Knight, PermGlas, Reliance water heaters, Revere, Rheem water heaters, Rheem/Rudd/Richmond water heaters, Rinnai, Security, Shamrock water heaters, Standard water heaters, State/Reliance/Sears brand water heaters, Thermo-King, Vanguard water heaters, US Craftsmaster, US Water Heaters, and Whirlpool water heaters..

  1. Peerless Heating Boiler Age Decoder

    If the boiler was manufactured from 1984 to 1999, the serial number ends in a four digit date code. “123456-1284” would be manufactured in December, 1984.

    If the boiler was manufactured from 2000 to present, the serial number ends in a six digit date code. “123456-200505” would be manufactured in May, 2005.
Weil McLain CP/serial number decoder at
  1. Weil McLain Heating Boiler Age Decoder, at      will decode the heating boiler's CP/Serial Number. At the company's website you will find these instructions:

    Enter the 7-digit CP/Serial Number of the boiler to obtain the manufacturing date and any associated information on the product.

    If the CP# is only 6 digits, enter a leading zero, e.g. 0137718. This look-up will not give manufacturing information for any other Weil-McLain product but boilers. Currently, no information is available for EG and EGH boilers.

    For those models you'll need to call the manufacturer, found at WEIL McLAIN Manuals

    When using off-site links like the one we give above, use your browser's "back" button to return to this website.

Carson Dunlop Associates' Technical Reference Guide decodes equipment data tags

HVAC Technical Reference Guide (C) Carson Dunlop AssociatesCarson Dunlop Associates' Technical Reference Guide (below) provides the most extensive HVAC equipment data tag decoder & other information to determine the age of boilers, furnaces, water heaters, air conditioners, and heat pumps by decoding the product serial number.

For the most complete and very detailed HVAC equipment data tag and age decoding information anywhere (about 128 manufacturers & brands)

Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment

Special Offer
: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.

The Carson Dunlop Technical Reference Guide provides both equipment data tag decoding data and also manufacturer contact information as well as historical dates for many brands of heating and cooling equipment. Included in the manufacturers listed are also makers of ancillary equipment such as controls, circulator pumps, etc., not just boilers, furnaces, and heat pumps themselves.

The age of a heating boiler, furnace, or heat pump can be determined by identifying its year of manufacture that is encoded in the unit's serial number (not the model number). The guides above give heater serial number decoding for each manufacturer and type of heating appliance.

For example, when decoding the age of an H.B. Smith heating boiler one of our readers provided the following from his boiler's data tag:

H.B. Smith, Westfield MA
Series G200
Boiler Model # G200-W-5CON
Serial # J80-2747

For an HB Smith boiler the age is typically the two digits following the letter at the beginning of the serial number. In this case the "80" following the "J" tells us that the boiler was manufactured in 1980.

Later H.B. Smith boiler serial numbers use the format XXyyyy-nnnn where yyyy will be the four-digit year of manufacture.

Manufacturers & brands of HVAC Equipment and Parts identified and decoded in the CDA Technical Reference Guide include about 128 different brands of equipment sold in North America

Aaon, Inc., Ack-O-Matic ,Aero Burners, Aero Environmental, Airco, Airtemp and Tempmatic, Aitons' Equipment - APCO, Allanson Transformers, Amalgamated Electric, Amana, American Standard, American Standard Water Heater Group, Amtrol, Anthes, APCO, ARCO Air, Arkla Industries, Armstrong Air Conditioning Co., S.A. Armstrong,

Baltimore Aircoil of Canada, Bard, Bell & Gossett, Borg-Warner, Bradford White, Bristol Compressors, Bryant manufacturing Co. of Indianapolis, Buffalo Package Equipment, Bulloch, Burke Water System Industries, Burnham Corporation,

Canadian Tire Corporation, Carlyle Compressor Company, Carrier, Chromalox Canada, Chrysler, Clare Brothers, Clare Mega Save, Clare HECLA, Clawsey-Sohrt Manufacturing Co., Climate Control Products, Climate Master, Climatrol, Coleman, Comfort Aire, Copeland, Copelaweld Compressors, Crane, Davie Environmental Equipment, Day-Nite, DMO Industries, Ducane Heating Division, Dunham Bush, Duomatic, Economite, Elect-Aire, Electric Apparatus COmpany, Elliot, Emerson Electric Company, Enmar Enmar Systems, Envirotron, Esso, Evcon Industries,

F.P. Industries, Fairbanks Morse, Fedders, Fess, Findlays Limited, Flamemaster, Fleetline, Florida Heat Pump Manufacturing, FMC Corporation, FP Industries, Franklin Electric Company, Frick, Friedrich, Frigidaire, Frigiking, Fuel Master Burners, G.M.L. Manufacturing, GSW Inc., Galais Manufacturer, Galaxy Boilers, General Controls (ITT), General Electric, Gilbarco, Gilbert and Barker, Goettl, Good Cheer, Goodman, Grimsby Stove and Furnace Ltd.,

Heat Controller Inc., Heil, Hill York, Hitachi, Homart, Honeywell, Howard Furnace and Boilers, Howell Electric Motors Company, Hydrotherm Inc., I.C. Burners, ITT, Inglis, Inter City Gas (I.C.G.), International, International Comfort Products, Intertherm, Iron Fireman, Janitrol Heating and Air Cooling Conditioning, John Wood Co., Johnson Air Ease, Keeprite, kenmore, Koldwave, Kool-Fire, LG,

The Arthur S. Leitch Co., Lennox Industries, Lincoln, Louis Allis Company, Luxaire, Magic Chef Air Conditioning Co., Mgnatec, Marathon Electric, Marcus Transformer, Marley Cooling Tower, Marvair, McLary, McQuay International, Mestek, Metzger, Metropolitan Oil and Gas Industries, Mid Continent Metal Products Co., Miller, Mitsubishi, Modine, Mueller, N'Furno, Nordyne, Norseman Boilers, Oakwood Iron Works (OIW), Olsen,

Payne, Pendell Boiler Ltd., Philco, Powermatic, Precision Boilers, Preston, Pyreco, Raypak or Raypak, RBI Water Heaters, Refcan, Reznor ITT, Rheem, Roberts Gordon, RUUD, Sanyo, SJC Corporation, Scarboro Pump Manufacturing Co., Sears, Sears Roebuck, Severn Boiler, Simpsons-Sears, Shell, Singer, Slant Fin Ltd., A.O. Smith, H.B. Smith Co., Smith Boilers, Snyder General Corp., Spacepak, Spencer Boilers, State Industries, Sterling HVAC Products, Sun Dial Manufacturing Inc., Sunscan Compressors,

TACO (Canada), TACO, Tappan, TECO, Techumseh Compressors, Teledyne Laars, Tempmatic, Temprite, Tempstar, Thermo Pride, Trane, Typhoon, Unitary Products, viessman, Viking, Warden King, Water Furnace, Watts Regulator Co., Weben jarco, Weil-McLain, Westinghouse, Whirlpool, White-Rodgers, Wood, Worthington Air Coils Ltd., York - Borg Warner.

How to Use Heating Equipment as Indicators of Building Age or Building Age as to Figure Equipment Age

PHOTO of an Octopus heating furnace, originally coal fired, converted to natural gas fuel.Indoor heating methods by historic periods or years: (adding date ranges is continuing for the list below - Contact Us to contribute).

Illustration of a Warn Air Heating System Using a Gravity Furnace

Our photo (left) shows a gravity warm-air "octopus" furnace; in its earliest version these furnaces, installed in the late 1800's in the U.S. were coal fired; many were later converted to oil.

Gravity furnaces rely on natural convection (warm air rises) to deliver heat to the occupied space.

There is no blower fan in the system. In their simplest design, the gravity furnace system included no ductwork whatsoever. Rather a large grate was provided in the building floor just above the furnace itself. In a multi-story house, heat rose to upper floors by passing up the stairwell or through open registers in first floor ceilings.

The gravity furnace we show at left was a more advanced design in which an "octopus" of duct work "arms" delivered heat directly to individual areas of the building.

The furnace in our photo is taking much of its "return air" from the basement - a very expensive way to heat a home. Earlier models eschewed ductwork and instead fed heat into the first floor of the building through a large central grate in the floor immediately above the furnace.

Audel's Oil Buerner Guide (C) Daniel Friedman

If you don't know what kind of heat your building uses, we explain how to figure out the answer at HEATING SYSTEM TYPES.

If your heating system is not working properly, see NO HEAT - BOILER or NO HEAT - FURNACE.

Beginning at HEATING SYSTEMS - home we discuss different types of heating systems such as

We also discuss various heating appliance fuel types (coal, oil, gas) as an aid in determining the age of a home or other building.

Antique Gas-Fired Floor & Wall Heater

Royal Metal Works gas-fired floor heater (C) InspectAPedia GL

Reader Question: Royal Heater in-floor gas fired heater history

I just bought a home in California. It has a dual sided, vent less, gas floor heater.

[Click to enlarge any image]

The only name I see is " Royal Heater". there are 2 valves; one for burner, one for pilot.

You need a key to turn them. On top of the unit is a view finder cap. Inside it looks like a 3 burner pilot

. I have attached photos of it. I'm trying to find any information on it. thank you.

[This particular heater] works beautifully and has been inspected. I want to find a operator's manual so I can maintain it.
- G.L., 16 Jan 2015

Reply: history of Royal Metal Works gas fired floor heaters in California


The Royal brand in-floor gas heaters were originally designed in California in the late 1920's - we have a patent (Publication No. US1666367 A) by Louis Clausing (Burlingame CA) assigned to the Royal Metal Works (his own company held in partnership with Max Schwartz describing an earlier version of the product dated 1928: "Heating device." U.S. Patent 1,666,367, issued April 17, 1928.

Your photos below illustrate the interals of this floor-wall gas heater.

Royal Metal Works gas-fired floor heater (C) InspectAPedia GL Royal Metal Works gas-fired floor heater (C) InspectAPedia GL

That that company was Royal Metal Works, 238 Van Ness Ave, in San Francisco, CA. That patent was cited by other product patents between 1943 and 1982.

Below at left your photo shows the gas controls including main valve (left) and pilot valvce (right-hand stem). At below right you've shown the pilot flame (I think).

Royal Metal Works gas-fired floor heater (C) InspectAPedia GL Royal Metal Works gas-fired floor heater (C) InspectAPedia GL

The company filed just three patents, two for heaters and one for metal bending:


Click to enlarge any image]

Royal Metal Works Gas Heater 1928 Patent (C) InspectApedia Royal Metal Works Gas Heater 1928 Patent (C) InspectApedia

There is presently a [different] California Royal Metal Company (in fact several of them)
who might be able to give you more historical data, is a sheet metal fabricator whose business was established in 1981 but who may have known of the older Royal Metal Works who made your heater:

Royal Metal, Ted Rieck Enterprises Inc, 1228 South Wright St., Santa Ana, CA 92705 USA Phone: (714) 542-4763 Web:

Unless you object, I'll add your photos to data we have at InspectApedia and will leave you anonymous (our default) unless you let me know that you want to be identified. That may attract comment from other readers who have similar products.

I'll attach the documents of interest to this article.

Watch out: I would not assume that the heater you have is safe to use without both a thorough visual inspection and testing for gas leaks as burning LP or natural gas in a defective appliance can produce fatal carbon monoxide gas.

I would suspect that your device may also lack safety features of modern gas heaters. If you are going to ignore my timid warnings then at least be sure you have working CO and smoke detectors properly located and installed.

Other antique wall heating convectors are shown at WALL CONVECTORS HVAC

Heating Equipment Data Tag Location & Identification

Data tag location on  the upper left side of a Weil McLain gas fired boiler (C) Daniel Friedman at Data tag location on a Peerless boiler (C) Daniel Friedman Paul GalowThis discussion explains where to find the data tag on air heating equipment.

To see specific details for your heater (boiler, furnace, heat pump, etc) you will need to know the brand and hopefully the model, then see


Heating equipment data tags are usually found on the exterior of the heater, usually on its top, front, or sides.

On occasion you may find the data tag information inside of the heating device, accessed by opening a removable front cover.

Often by removing the front cover of a forced warm air furnace, the equipment data tag is found inside the furnace jacket on the left, right, or directly on the exposed face of the furnace itself.

In our first photo shows gas fired heating boiler located in a garage.

The yellow arrow points to the common location of the equipment data tag on the upper left side of a Weil McLain heating boiler. [Click to enlarge any image]

Our second photo above shows the common location for the equipment data tag (circled in yellow) on a Peerless cast iron boiler.

On this page we illustrate typical equipment data tags on heating boilers and furances.

Our first photo below shows the data tag for a Smith Cast Iron Boiler.

You will find the model number identified on this heater as SERIES 19A SERIES-S/W-5, and SERIAL NUMBER FA2002-533.

Our second photo below shows the data tag on the exterior of an HB Smith heating boiler, Model BB14-*-4, (the * indicates that this is a steam boiler), though in my over-shot photo the serial number is not quite visible.

Data tag on a Smith cast iron boiler (C) Daniel Friedman Older HB Smith boiler data tag showing model and serial number (C) Daniel Friedman at

Furnace Data Tags Often Are Behind An Access Cover

Some gas furnaces sport a data information tag on the furnace interior left or right side, visible only after removing the front cover.

Below is the data tag for a rusty old Holland gas furnace, visible on the front of the furnace above the gas burner tubes, accessible only when the furnace front cover door has been removed.

Holland gas furnace data tag (C) Daniel Friedman at

Other Information Tags Are Not Equipment Data Tags

Watch out: not all of the information labels, tags, stickers seen on and in heating appliances are data tags. Don't get confused and don't think that because you cannot find the model and serial number on a label that the equipment has no data tag.

Look further on the outside and inside of the device. A true "data tag" includes brand, model name, and serial number, often along with other information.

Other labels on heating equipment may give warnings or usage instructions, like the label I show below. This sticker gives model and oil burner nozzle guide information for System 2000 boilers by Energy Kinetcs - a boiler I installed in a New York home nearly 20 years ago) but this is not the unit's data tag.

Energy Kinetics System 2000 information tag, this is not a data tag (C) Daniel Friedman at

Taking a further look around this same System 2000 Energy Kinetics boiler we spot the actual boiler "data tag" giving its model and serial number on a smaller sticker that I show below.

System 2000 Energy Kinetics boiler model and serial number data tag (C) Daniel Friedman at


Age of the Boiler or Furnace as an Indicator of Building Age

Flamemaster gas furnace logo (C) InspecApediaExample of How to sort out shared names such as Flamemaster & Climate Master

If the heating equipment in your building is original - which may be determined by visual inspection, by knowing the building age, or knowing the heating system age, then each of these can inform us about the probable age of the other.

For example, an original Flamemaster (or Climatemaster) gas fired heating furnace is probably 40 or more years old even if you cannot find the date code in the furnace serial number.

Watch out: Names and who is using them can change over time: for example the name "Flamemaster" appears on other products such as sealants, coatings and packaging produced by Flamemaster in Pacoima California, US - not a heting equipment manufacturer.

The product line Flamemaster gas furnaces shared product designs with ClimateMater. ClimateMaster continues in business (in 2015) as a manufactuer of geothermal heat pump systems.


Continue reading at AGE of HEATER BOLER FURNACE FAQs - Q&A on decoding specific brands of heating equipment via serial number, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see AGE of AIR CONDITIONERS & HEAT PUMPS - data tag decoding

Or see LENNOX HVAC products Age PDF

Or see HOME CONSTRUCTION CATALOGS 1950 - catalogs including heating equipment from the 1950s

Or see MANUALS & PARTS GUIDES - HVAC - sources of more information including heating & air conditioning equipment age, history, manuals & manufacturer contact information

Or see these

Articles on Building Component Age

Suggested citation for this web page

AGE of HEATERS, BOILERS, FURNACES at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Questions & answers or comments about how to determine the age of an air conditioner, heat pump, boiler, furnace, or water heater. .

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

HTML Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman