Flooded Water Heater (C) Daniel Friedman Hoyt Water Heater Age Decoder
Hoyt water heater data tag indicates heater age

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Life expectancy of a Hoyt water heater:

This article describes how to read the data tag and de-code its numbers to determine the age of a Hoyt water heater.

We explain the current and past owneship of Hoyt water heaters and give company contact information. We show typical water heater data tag model and serial number formats and note where in that information the year or week or month and year are encoded in the Hoyt water heater serial number.

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How to De-Code the Data Tag on a Hoyt Water Heater - Age Determination

Hoytt or "Hoyt" produced water heaters until 1989 when the company was purchased by AMERICAN WATER HEATER

Hi Test Hoyt Water Heater Age De-Coding Tips

Query: (Nov 5, 2012) Alexandra said: I am trying to find the age of my Hi Test Hoyt water heater. The Serial is SN A87RNH1373190, model A40HM

Reply: best guess 1987

The Hoyt Water Heater company "... have been engaged in the business of manufacturing, selling, repairing and servicing water heaters in Los Angeles since 1911 under the trade name of Hoyt Heater Company and Hoyt Automatic Water Heater Company." - Hoyt Heater Co. v. Hoyt 68 Cal. App. 2d 523 Hoyt was subsequently purchased by American Water Heaters or the American Water Heater Group.

From Carson Dunlop Associates Technical Reference Guide, the most complete HVAC and water heater age decoding guide available, the first two digits of the serial give the year and the second the week of manufacture.

Adding to what my mom calls "a lot of 'who struck john'" confusion,

  1. A.O. Smith owns GSW
  2. which in turn owns American Water Heater Company (AWHC)
  3. which in turn owns Polaris.
  4. American Water Heater Group, 500 Princeton Rd., Johnson City TN 37601 Tel: 800-999-9591
  5. Website:

Reader Query: (Nov 11, 2015) chris said:
i am trying to find the age of my hot water heater. it is a hoyt and has the serial number:544872.

Reply: I'm guessing from several reader serial numbers provided that in the 1980's Hoyt Hi-Test water heater age was encoded in positions 4&5 of the serial number: in your case 1987

Reader query: 2016/06/05 David Stackhouse said:

Trying to find out age and value of Hoyt automatic water heater; size 3 serial number 16372 patent July 15th 1919. Feel free to contact me at for pictures if necessary

This question was posted originally at AGE of WATER HEATERS


This heater has a short serial number - send me a photo of its labels and I'll try to research it further; If I had to guess from just what's given it'd be 1972.

Reader Comments about Hoyt Water Heaters

Question: life expectancy of a Hoyt Hi-Test water heater

(Mar 5, 2014) SA said:
Regarding life expectancy: I purchased a 50-gallon Hoyt Hi-Test water heater on 28 Aug 1986 from Orchard Supply Hardware for $169.88. Serial #1148036. I replaced this unit today, having received nearly 28 years of excellent service from it. A few days ago, it began leaking. The reason for the longevity of service is probably because it has been used with soft water. Coincidentally, my plumber chose a new unit manufactured by American Water Heater Company, the same company that bought Hoyt. 4 Mar 2014


Thanks SA for this posting, having real reports of heater life are very helpful to everyone. I agree that water chemistry is a significant factor in heater life. Tell us - did you ever in 28 years drain and flush the water heater as manufacturers recommend or were you able to get away with skipping that task (as does almost everyone)?

Troubling is that it's not easy to find a "1986" in your water heater's serial number. I suspect it was made on day 114 of 1980 and had been in stock even when you purchased it, but that's just a guess. We see from various reader comments and questions that Hoyt Hi-Test water heater age encoding in serial numbers is a bit variable.

Reader follow-up:

(Mar 9, 2014) SA said:
You're welcome, Dan. Count me in with "almost everyone," it was not even on my radar. The Hoyt water heater was never once drained and flushed during its 28-year life. But, most likely due to our water softener system, when the Hoyt was drained for the first time a few days ago, no sediment came out of the hose. I will be paying closer attention to our new water heater. But somehow, I don't expect to get the same kind of longevity from the new unit.


I agree that too often newer equipment, even by the same manufacturer, may have a shorter life; thinner steel, push to reduce production costs &c;

If you have not tossed out the old heater it would be instructive to pull the sacrificial anode to take a look at its condition; photos of the heater and its data tag and of the anode would be valuable to our readers if they're within your scope and not too much work. The CONTACT link on our pages works for sending pix if you like.

Question: Hoyt water heater, serial number 93355 control mechanism needed

2016/09/07 Bob DeGroot said:

Hoyt water heater, serial number 93355, 75 gallon copper storage tank, has quit working. the thermocupler (sic?) was not the issue according to our plumber. The control mechanism itself may need to be repaired or rebuilt in order to fix the problem. Can I find this original piece, or can it be rebuilt?


Bob we discuss Hoyt water heaters a bit at

Your question was originally posted at DIAGNOSE & FIX HEATING PROBLEMS-BOILER a home heating boiler article - perhaps because Google's search found "hot water heating boiler" or somesuch.

I'm not sure just what "control mechanism" we're looking for here. ( I suspect you mean the water heater thermostatic control. )

Hoyt water heaters went out of production in about 1989 or 1990. Many water heater parts are, however, generic an can be replaced by a generic control. Hoyt - at least the Hoyt water heater brand, was purchased by American Water Heaters. So you might also find a suitable part from that company.

Contact information for American water heaters is at WATER HEATER AGE & MANUALS - home


Continue reading at WATER HEATER AGE - home, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


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