View Full Version : blower motor size
01-17-2011, 03:33 PM
how can i determine the proper size blower motor on an oil furnace? i have a magic chef L6284D3 serial #16087KAB 84000btu output. the blower motor has obviously been replaced by a single speed motor and there is a label indicating a motor wired for low and high speed. lots of questions ,rpms,hp, amps etc. thank you
01-18-2011, 12:04 PM
type those numbers into google + spec's
01-18-2011, 02:58 PM
if that would have worked i would not be here asking you fine people for help. oil service guys won't give me any information either. all i want to do is change an apparent hack job or emergency fix to the right motor. don't know if the specs on the current motor are good to use. thankyou
01-18-2011, 03:32 PM
Only a service dealer for that brand ( I don't know who makes Magic Chef HVAC) would have access to a parts and service manual for an old furnace. If Google Manuals doesn't have it, you might need to look for a dealer.
01-19-2011, 11:13 AM
If its working ok, why mess with it? Running it high speed cannot hurt anything, probably increases the efficiency anyway.
Must be very old if magic chef was making oil furnaces!
01-19-2011, 02:42 PM
escuse me but obviously it is NOT working ok if i had to open it up and SEE that it is NOT THE CORRECT motor for the application. it was noisy and i found the squirrel cage loose and the motor shaft also seems too loose like the bearing is starting to go. slight oil seepage also. motor diameter seems too small for the mounting band also. yea it's been working 'til now but i expect trouble soon and i want to get the RIGHT MOTOR! gee wiz i was hoping to get help here.
01-19-2011, 04:33 PM
I assume it is a direct drive motor (motor directly attached to blower wheel). I know Grainger carries a wide selection of blower motors, but from what I have seen, they have the motor (by itself) without the blower connected.
Anyway, you are probably looking for something in the 1/2 HP - 3/4 HP range. If you look at your current motor, what specs are on the label?
I can check my blower motor for you. It is an older one, but my electric furnance is also ~80k BTU and the speed is set to med-high for heat and high for AC (I believe).
You probably are looking at something in the 1200 CFM range for flow. With a multi-speed (or variable speed) you can slow it down to get the delta-T across the furnance that you are shooting for.
01-19-2011, 08:14 PM
how can i determine the proper size blower motor on an oil furnace?
By asking a dealer or authorized factory service technician. We have tried to make that point. No one has a genie in a lamp that can just poop out a motor spec for you , sight unseen. How old is that furnace? Is it even worth spending money on a new motor??
02-03-2011, 12:32 PM
When I had to replace the motor for my 40 year old Janitrol, no one could cross refference the motor anywhere.
Than for the hell of it when I was handed the wrong motor and Grainger and told them it was wrong, they looked up my old motor again, but left off the last digit.
Bingo! They found the exact replacement.
Try searching by leaving off the last digit of part number.