Determining Water Heater Age

Need help in determining age of water heater please. It is an American Appliance Mfg Corp 40 gal natural gas fired water heater, serial # 1914654. I have used the calculator that NACHI has provided, and when I plugged in the numbers, the response was, " Invalid Serial number". Any assistance on this will be appreciated.


Typically, with The American Water Heater Company, the 1st two numbers are the year and the 2nd two are the week. You may have written the numbers down wrong…


The first two numbers are the year it was manufactured and the second two number are the week within that year that it was manufactured.
For example, if the first 4 digits of the serial numberare 9932, then it was manufactured in the 32 week of 1999.

Thanks for the replies. I, hopefully, have attached a photo of the data sticker. The serial # is A1914654. I left off the “A” in the orginal post.


American Appliance Mfg. Corp. appears different than American Water Heater Company. I missed that in your 1st post.

I don’t know the age for sure. Was there an ANSI date? Usually that is within 3 or so years of the manufacture date.

I believe your serial number is I914654 with that first digit being the letter I rather than the number 1. Some manufacturing plants, especially the older ones, took a while before upgrading their stamping machinery so that there was a distinct difference between the letter I and the number 1.

AAMC went through some changes in 1990 that also affected how they coded their serial numbers. Most manufacturing plants west of the Mississippi apparently went to using a serial number starting with a letter and followed with 6 digits. East of the Mississippi continued using their older 10-digit serial number. However, there are 10-digit serial numbers starting with a letter and some that do not include a letter. One will occasionally also find 11-digit serial numbers that start with one letter followed by 10 digits. Most of the confusion occurred in the 1990-1994 period.

I’m still researching where the 11-digit numbers came from.

So, to answer the original question, I believe you have a water heater manufactured in the 46th week of 1991.

Thanks again fellas. I really appreciate all your replies. Larry, I did not see an ANSI number anywhere on the unit. This heate was back in a closet with not much room to look around.

I have to put a plug in here now. I come to this board often to read and learn, and I have found that this is the only board that I can rely on for quick accurate replies. Thanks again.

John what calculator and where is it?

Help me out please, what does NACHI offer to help deterime ages of Water heaters and furnaces? You stated a calculator??? Thanks

There’s a water heater calculator around here somewhere, but I was never able to get it to work, so, out of frustration, I finally deleted it and/or references/links to it.

I do have a lot of water heater information and coding guides over at About Homes.

Thanks for the info, looks great but have to join to get info, right now I can’t keep buying things, any other ideas?

Hold on, Brian.

I’m reorganizing some things in order to make the information available to you.

Patience, oh Grasshopper, patience.

Have a margarita while you wait :margarit:


Let’s see if this works:

Determining water heater age using serial numbers

It does.

Be right back with some more.


Determining manufacture date from water heater serial numbers for Bradford White
(and U S Water Heater).

Russel I see your on the board alot, quite the charactor. You tell it like it is. Grasshopper? oh if you only could talk to my freinds, I don’t do much of anything in slow mode. Don’t get me wrong I do a through inspection but as a HVAC installer and general contractor time is of the utmost importance and am always thinking of the next step which makes me appear grasshopper like.

Hey russel could get the first pdf to work??? something about decrypting
I don’t know, come on come on feed me :slight_smile:

Hey, Brian.

I think you need to upgrade your version of Adobe Reader.

I thought I have? I have 7.0. I’ll try to update but am one dialup connection and it takes like and hour. So thanks and I’m going to hit download and go to bed and let it do it’s thing. Getting up early have a bathroom remodle to start, (should take me about 20 mins hehe)

Here’s the water heater age calculator that you may have had problems with: