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abp32
18-12-2015, 10:22 PM
hi there all

I spoke to a engineer today who swear blind if you have a r290 system you can replace the gas with r404a and it will run the same you dont even have to change the oil or the pot , he says he has done it a few times and the fridges are running fine after a year or so , i mean come on seriously this cannot be right ?

Rob White
19-12-2015, 01:33 AM
.

404 and 290 have very similar properties, they can and
do use the same compressor. 404 will be in short demand
very soon so tell the engineer to get used to 290, it is the
future.

Rob

.

Rtic
19-12-2015, 01:59 AM
Compressors manufactured by Embraco labelled r290 are exactly the same as their equivalent r404a compressors. So yes, you can empty an r290 system and replace it with r404.

We do the above fairly regularly with the ‘Walls Ice Cream Display Freezers”, which are always blocking out; we empty the system resolve the blockage and recommission with r404.

I suppose with the current phase down, which will really hurt in 2018, then it will be the other way round. However the rumours in the industry is that r407f is to be the replacement and pretty much the drop in for r404. J&E Hall already advertise most of their r404 systems as compatible with r407f.

Grizzly
19-12-2015, 03:36 AM
Hi Rob and Rtic.
Some useful info.
Thanks.
Grizzly

chemi-cool
19-12-2015, 08:07 PM
R290 is used only for environmental reasons, I back Rtic words and add that r404A is a problematic refrigerant.
I have seen a few units run with R404A where the refrigerant stopped cooling and head pressure went sky high, all components was fine, replacing the charge sorted the problem.
In a big plant where as an outsource contractor, I look after many low temp units, I have replaced all R404A with R507 and never had a problem since.

Most manufacturers of small compressors are only making two kinds of compressors, low temp and medium,high ones so if the refrigerants have similar properties, you can change them without any problem of performance.

Tayters
19-12-2015, 09:46 PM
I have seen a few units run with R404A where the refrigerant stopped cooling and head pressure went sky high, all components was fine, replacing the charge sorted the problem.

Yes, not that I have witnessed this myself but the chest freezers in Lidl's (or was it Aldi?) would throw a wobbler and this was the cure, replace the R404 and all working again.

nike123
20-12-2015, 08:45 AM
hi there all

I spoke to a engineer today who swear blind if you have a r290 system you can replace the gas with r404a and it will run the same you dont even have to change the oil or the pot , he says he has done it a few times and the fridges are running fine after a year or so , i mean come on seriously this cannot be right ?

Since R290 compressor runs usually on mineral oil, retrofitting R290 to r404A should require same procedure as retrofitting R22 to r404A. That include changing oil to POE type!

Also, depending on evaporation temperature, with same compressor displacement, according to Coolpack software, capacity increase is 10-20% with use of R404A on same compressor, and therefore, condenser should be checked for sufficient heat rejection capacity!

abp32
07-01-2016, 10:27 PM
it must be small fridge he is talking about

Rivelino
12-01-2016, 02:09 PM
Apologies for picking up an old thread. I read post re: Walls freezers. I have a Foster 2 door bench type freezer on a Danfoss pot that leaked on the return. Designed with 290. Has anyone ever dropped 404 in to one of these smaller applications with positive results. The only issue I see on the smaller hermetic applications is the oil as 404 should be run on no more than 90% charge of polyol ester (as I recall). Any help greatly appreciated. Not a big issue as can grab a canister of 290 but thought it worth asking and for future reference.
Cheers