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Hoyt water heater Model 40EF S/N 0000115068

need to determine age of this unit, not the original owner. I've checked about 10 websites, with no results except for decoders for the "big names". Any historians in the group, that could help me decode the S/N???


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Hoyt was purchased by American Water Heater. Maybe a call to them might tell you something.

    There was an error rendering this rich post.

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,335
    edited December 2020
    Hi, What numbers do you see on the unit? Look for the ANSI number. It is renewed every three years, so that will give you a good clue. Look on the relief valve. Some are stamped with the year and week. Post photos. We like photos! Also, some controls have the date on the back side.

    The best way to know the true age of the heater is to have a look at the anode. If there is anything left, replace it. It is the key to heater longevity.

    Yours, Larry
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,050
    edited December 2020
    Hoyt water heaters used to be made here in Oakland, then moved to Reno and then they were gone in the 90's.
    Some old monel tank Hoyts are still around.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab