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Electric furnace date


Robert Jones
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The style of the sticker would suggest at least 30 years old. I can't help beyond that.

My best guess with most electric "furnaces" I find around here is that they are the same age as the house. Keep in mind that there's no heat exchager to rust out. Any elements, no matter how old, could burn out tomorrow, but they can be replaced, as can a bad blower motor. Efficiency wise, I doubt that a new one is noticably better than a 50 year old model. So...actual age doesn't worry me that much with electric furnaces. I run them and "clamp" the element wires. They are either working or not.

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The model number has no date info. It has coding for the place of manufacture and also indicates that it's a horizontal electric furnace, 208/230v single phase and 60 hertz.

There is a separate small rectangle-shaped tag with rounded corners that is clearly labeled "SERIAL NUMBER". It starts with 4 numbers and 1 letter, space, then 5 numbers. 5178M 99989 would be manufactured in 1978.

Efficiency wise, I doubt that a new one is noticably better than a 50 year old model.
Improvements in sequencing.

If I was buying a house with an electric furnace (no matter the age) and it has AC, I'd be puttin' in a heat pump moments after closing.

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Am I right in thinking that "58" is a code for the factory location?

You're probably right. In the serial number example I posted above, the first 2 digits are listed as the "division".

Columbus 51

Des Moines 53

Ft Worth 54

Heatcraft 55

Stuttgart 56

Marshalltown 58

Toronto 63

So Robert's tag is missing everything after the first 2 digits. The furnace was assembled in Marshalltown, IA, which is also the original location of the Lennox Furnace Company, incorporated in 1904.

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Quote: Efficiency wise, I doubt that a new one is noticably better than a 50 year old model.
Improvements in sequencing.

Bill, if you're still there...isn't sequencing of the elements more to do with providing a soft amp-draw start than it has to do with efficiency? I thought that with electric furnaces you basically get out what you put in.

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Richard,

As usual, you are correct. Heat relays or time-delay sequencers are used for "spacing the load". I should have used the word staging instead of sequencing.

Some recent electric furnaces are capable of having multiple stages as an energy saving feature. Two or more elements can be sequenced on within each stage of heat. I know of one Lennox electric furnace that was configured for 6 stages. It was accomplished with multiple outdoor thermostats.

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When I get those old Lennox furnaces; if the manual or other documents are there, I usually check out the manual for a publication date stamped in the lower corner of the manual, warranty card, etc.. It's usually pretty close to manufacture date.

ONE TEAM - ONE FIGHT!!!

Mike

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