View Full Version : is there a replacement chart here
07-07-2005, 10:07 PM
that shows what freons to use when doing a change out?
im replacing a 502 system, and the new compressor is listed as 502/404..the new expansion valve says 404,502,402a and 507..nothing about 408a..
[Edited by primmers on 07-07-2005 at 10:18 PM]
07-07-2005, 10:27 PM
07-08-2005, 07:52 AM
It may not be mfg specs. butttttttt I have used 408-a with MO in close coupled systems where the evap is above the condenser with 0 problems. Im talking about 50 systems that were done in 96 and are still running strong. Dont think I would use it on long runs without changing the oil to AB. OMO and past experience.
07-08-2005, 03:40 PM
this compressor is on the roof right above the evaporator..
primmers.. i guess we have been dancing all around what you are trying to get... that is, some info on a 408 system.
502 converts with 408a cause it uses the same oil. It is a drop in for 502 basically with just slight temperature glides.
Any time you see a TXV for 502 you can use 408 and 404.
Your compressor being on top of your evap will not be a problem for oil return. You would need a trap installed for every 20' of vertical lift of suction line.
With the conversion of 502 to 408 you will have very little change in superheat settings with your TXV.
07-08-2005, 04:52 PM
the thing that got to me was there was
no mention of 408 on the txv or compressor..
but since 408 is a mid term freon, i guess the
manufactures wont mention it..
ive done a couple 502 to 408 before, but wondered aloud here about the ignoring of the product(408) on parts..
also i wonder why manufacures still use r12 as a standard..
why not design condensing units to handle the higher head pressure for example..
07-09-2005, 03:20 AM
Look at a PT chart, and you'll see that 408A and 502 are virtually identical.
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