not confused bewildered

[devlin maguire]

So if R422D can be used as a drop in for R22,R502,& R404 can R404a be used in a R22 system
as a drop in
Dev

[cadwaladr]

no no no no,not without serious modifictions.

[devlin maguire]

I dont get it if R422D can be used as a drop in for 22 or 404 why is'nt the obverse true if 22 & 404 are the same in respect of a replacement surely they are interchangable , I know it is a simplification of the basic issue so what would need modification txv, oil, ??
Dev

[monkey spanners]

For R404A, system would need an oil change to poe, the tev would need changing and a bigger orifice fitting, in certain cases the liquid line would need to go up a size.

I had planned to replace the R22 in old milk tanks with R404A but now R407F (not R407C) looks a better prospect, only needing an oil change, (though o rings etc should be changed too in either case).

Have not been impressed with R422D at all.

[jdunc2301]

Drop in's can be seriously confusing, and often cause more problems than they are worth!

[devlin maguire]

So would R404a be ok for a beer cellar as the demand is quite low
Dev

[Tayters]

I think it all depends on the oil in the system.

R404A requires POE oil. With the mineral oil (not sure about AB though) when refrigerant is in liquid form the oil gets carried along quite happily. When the refrigerant is in vapour from it relies on clinging to the chlorine atoms (if memory serves me correct) in the refrigerant to get back. No chlorine atoms in R404A so harder to get the oil back leading to oil logging in the evaporator.

The drop in's have a small percentage of a HC to serve a similar process when refrigerant is in vapour form.

Hard to say what the exact results would be in the case of your beer celler. Low load could equal low refrigerant velocity therefore greater risk of oil logging. There again stick POE in it and it could clearng muck from the inner wall of the pipes causing aggro.

I used R422D once in a freezer cold room - seemed to work with no tweaking required but then I left the company a few weeks later so can't comment further.

Could you use R417A? - tried that in a few AC syctems and seemed to work well.

Just to throw a spanner in the works I came across this thread:
http://www.refrigeration-engineer.com/forums/showthread.php?807-R404a-mineral-oil

Puts my theory out a bit. Perhaps use the beer celler as a Guinea Pig to settle the argument!

Cheers,
Andy.

[cadwaladr]

how big is the beer cellar,i would try to convince the owner to change the system nothing worse than warm beer!

[devlin maguire]

Thanks Guys, it a small cellar 30M3 or so, He is a tight wad so trying to sell him new kit is non starter, it is a old system probably 15 years at least an IMI unit fitted by city as part of there deal with the brewers, might go down the road of a comp change etc if the aforementioned scrooge goes for it
Dev