Furnace age needed

First time I have run across this brand of furnace and none of the cheat sheets have it either. I suspect it is original equipment (condo built in 1978, but though one of you guys might know for sure. Thanks in advance !

Fedders forced air unit
Model CU6045N1D
Ser# FP255416

Here are a couple of pics also. Looks like some work was done on the heat exchanger at some point.

Can’t help exactly but it does look like a 70’s unit.


Fedders manufactured many furnaces’ with that same model number for 10 years. They started manufacturing them in 1971 and then changed the model number in 1981. They all have 42,500 BTU’s.

So you know the furnace is original at this point.

To get the exact date… you need to obtain the AFUE of the furnace. The lowest efficiency furnaces that were manufactured in 1971 had an AFUE of 59.4. The AFUE continued to get better up to 1981 which was 68.1.

Anything in between those years can be estimated.

Thanks you guys !

April 1979.


What information do you have that pinpoints this date for Fedders?

Please furbish…

Technical Reference Guide, 2001 edition, page 56.

FP is April 1979.

Thanks. I have that manual but I keep it in my tool bag.

That’s the same manual that I was going to post the contents here with all the dating information until someone called the Carson Dunlop police.

Bushart has two Jobs? :margarit: