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Discussion Starter · #1 ·
OK how do I search for a very old system? I have the model number and the serial number, but when I go to the mfr website I get no results. I do believe the date of mfr was July 1978 based on s/n, but can't seem to find anything else out about it, especially the SEER rating, (Which is the challenge I was given)....Any old timers can help out this 62 y/o newbie?
 

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A 1978 unit may not have a seer rating.

It may have an EER rating which is derived from testing at 95F outdoor/80F indoor.

Probably in the 6 to 7.5 range unless it was something fancy.

Just remember- don't assume what you have now is the correct size.
 

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A 1978 unit may not have a seer rating.

It may have an EER rating which is derived from testing at 95F outdoor/80F indoor.

Probably in the 6 to 7.5 range unless it was something fancy.

Just remember- don't assume what you have now is the correct size.
Most likely correct.
SEER ratings were not really instituted until around 1978.
 

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Rheem serial #s are not easy to read and it may not be 1978.

If you can find a sticker on the contactor or get the serial # off the top of the compressor and it has a 78 in it then it may be true.

Pretty rare those may still be running. I put a Canadian built Keeprite in Mom's house in 1980 and it wore out and 99% of them are worn out and going away.

Back then it would have been between 7-8 but we only had one style of unit to choose from so no one cared. I have found info on some very old Lennox units and none were over 8 at that time.

However those old machines a lot of them had Tecumseh compressors which were built like tanks and old school Maytag washers so a few are still running.
 

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Older units die/get replaced because the valves wear out and the compression ratio is gone. Then your Delta T is 10-13 and it cannot keep up with the demand.

We are talking about recip compressors as scrolls are mostly under 20 yrs old.

Plus a connecting rod breaks and they seize up or the windings short.
 
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