How to make a guess at heating boiler or furnace age when there is no obvious date or decodable serial number on the unit's data tag.

Page top photo: older HydroTherm boilers usually carry a data tag that includes a serial number but that number cannot be readily decoded to give the date or year of manufacture.

Boiler or Furnace Age Determination from Surronding Contex & Clues

Here we list tips for making an intelligent guess at hvac equipment age when there is no direct age decoder available.

When there is no direct age decoder for a boiler based on its serial number we look at the surrounding and contextual clues including the items given below.

• Age of the building
  
  where the boiler or furnace is installed, refined by any evidence suggesting that the boiler replaced an older one in the same building
• Contact the manufacturer
  
  by calling in the serial number, the company may be able give you the manufacture date for your heating boiler or furnace.
• Service dates and notes
  
  on the boiler's service tag usually found attached to the boiler or a nearby pipe
• Installation manual publication date and possible notes
  
  printed or hand-written on the heaing equipment's instruction manual if it was left with the boiler.
  
  Remember to look around the boiler to see if the manual was stashed nearby.
  
  The publication date for a boiler or furnace model's manual can often be found by searching on the boiler or furnace model ID or checking PDF downloads for the heater's installation or service manual, like those given on each of the pages that provide manual downloads for heating equipment found
  
  at MANUALS & PARTS GUIDES - HVAC

• Boiler / Furnace company history
  
  (given above on this page for Hydrotherm). Boiler brand and model number combined with a check at the boiler manufacturer can give a range of years over which that model was manufactured.
• Patent numbers
  
  on a boiler's data tags can set a floor (no-older than) under the heater's age: look up each patent and note its year of publication.

• ANSI or other standard number and publication year
  
  included on the boiler's data tag. For example, the HydroTherm boiler data tag provided courtesy of an InspectApedia reader in 2024 includes ANS Z21.3 a-1983, a national standard for low pressure boilers.
  
  That publication date for the standard, imprinted on the data tag, tells us that this boiler is no older than 1983 and was probably made in the 1980s.
  
  Dates of government standards that often appear on the boiler's data tag even if the serial number itself is not easily decoded
• Manufacturer's address on the boiler data tag:
  
  in the example of the data tag just above: HydroTherm, Rockland Ave., Nowalk, New Jersey 07647 can tell us something about the boiler's age:
  
  - when was the manufacturer at that address ? The HydroTherm history notes above probably place that address before 1991.
  
  - notice address details such as the presence of a zip code (on U.S. equipment). In the U.S. the first zip codes were in use as early as 1963.
• Notes written by installer or owner;
  
  sometimes a hand-written installation date for the boiler or furnace or other heating equipment written on the boiler jacket or on the manual
• Owner's records of installation or service
  
  of the boiler or furnace
• Evidence or record of whether or not the boiler is the original one
  
  for the building it serves that can set a floor or "no older than" date for a boiler.

...

---

---

ADVERTISEMENT

---

---

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-01-16 by anzaldi73

Hi do you know the age of my unit? Would you recommend we change it dont want to be stuck one winter. Thank you

[Click to enlarge any image]

On 2021-01-16 - by (mod) -

That looks like a Hydrotherm gas boiler data tag.

By calling-in the serial number the company can often give you the date: USA 413 564 5515 or Canada: 905 672 2991

 

...

Continue reading at MANUALS & PARTS GUIDES - HVAC, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• AGE of a BUILDING
• AGE of AIR CONDITIONERS & HEAT PUMPS
• AGE of HEATERS, BOILERS, FURNACES
• AGE of PLUMBING MATERIALS & FIXTURES
• AGE of WATER HEATERS - data tag decoding, contact information for water heater manufacturers, water heater manuals
• BOILER / FURNACE AGE GUESSER
• BOILERS, HEATING - home
• BOILER / FURNACE AGE GUESSER
• DATA TAGS on AIR CONDITIONERS for help decoding the equipment age and other specification
• DATA TAGS on HEATING EQUIPMENT
• FURNACES, HEATING - home
• MANUALS & PARTS GUIDES - HVAC - home - Master Index to All Brand Names & HVAC manuals, wiring diagrams, installation and repair guides

Suggested citation for this web page

BOILER / FURNACE AGE GUESSER at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING SYSTEMS

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

Ask a Question or Search InspectApedia

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.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---