Duo-Therm® HVAC age

How to determine the date of production/manufacture or age of Duo-Therm® brand HVAC Systems.

The date of production/manufacture or age of Duo-Therm brand HVAC equipment may be able to be determined from the serial number located on the data plate for some systems.

Note: Traditional heating and cooling systems no longer manufactured under Duo-Therm brand name. Duo-Therm brand heating systems are believed to have been last manufactured in 1975, and Duo-Therm A/C systems for recreational vehicles last manufactured under Duo-Therm brand name in 1985.

Parent Company: Originally part of the Motor Wheel Corporation. Later acquired by Electrolux which eventually became Dometic brand.

Example serial number styles/formats found:

Style 1: A7500525

Style 1: A7500525

Year of manufacture is believed to be 2^nd & 3^rd characters (digits) combined.
Month of manufacture is believed to be the 1^st character (letter).

This information is unconfirmed!

For more information on this brand, see history information below.

_{Thank you to Gary Dehm for providing the data plate photo above}

Brand History ¹:

Duo-Therm was originally part of the Motor Wheel Corporation who, prior to WWII, was the largest producer of automotive wheels in the world.

Motor Wheel Corporation diversified during the war effort to produce numerous parts for the military including wheels for a variety of vehicles (including tanks), brake drums for aircraft, and even shell casings and projectiles.

Prior to WWII, Motor Wheel Corporation had developed a furnace it marketed under the name "Duo-Therm." At some point they also developed an oil-fired water heater.

They eventually focused on mobile home and RV heating/cooling products sometime during the 1950’s. By 1961, Duo-Therm brand lines were all consolidated to the La Grange, Indiana facility, and the Lansing MI facility abandoned.

By 1975, they appear to have abandoned the heating systems to focus more on roof top a/c systems for RV’s.

In 1985, Electrolux acquired Duo-Therm from the Motor Wheel Corporation. Duo-Therm had become known for the air conditioner systems manufactured for the Recreational Vehicle industry. Electrolux leisure appliances division was renamed as "Dometic" brand in 1960's. The Duo-Therm lines were rolled into the Dometic brand name, and now only a few old dinosaurs remain with the Duo-Therm brand namesake.

1920 - Prudden Wheel Company and Gier Pressed Steel & Auto merged to form the Motor Wheel Corporation in Lansing, Michigan
1929 - Introduced the Centrifuse, a centrifugally cast composite brake drum, which was later used on many aircraft and trucks during WWII due to their strength and performance
1934 - Motor Wheel Corporation controlled about 1/3 of all wheel production in the United States
Late 1930's to early 1940's - Developed a furnace under the brand name "Duo-Therm". Also developed an oil-fired water heater under the same brand.
1940's - Motor Wheel Corporation diversified during the war effort to produce numerous parts for the military including wheels for a variety of vehicles (including tanks), brake drums for aircraft and trucks, and even shell casings and projectiles
1961 - Duo-Therm line relocated to La Grange Indiana. Lansing, MI plant effectively abandoned.
1964 - Goodyear Tire acquired Motor Wheel Corporation
1975 - The Motor Wheel plant in Lansing officially closed - believed to be the last manufacture year for heating systems
1985 - Duo-Therm (then manufactured in La Grange, Indiana) was acquired by Swedish-based Electrolux under their existing "Dometic" brand - believed to be the last year for any Duo-Therm branded systems
1986 - Motor Wheel Corporation Centrifuse casting operations relocated to Chattanooga, TN
2001 - Electrolux sold Dometic to EQT III and Dometic Group was created as a separate company.

¹ _{History information from various industry sources}

Page last updated: 12/06/2024

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