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Universalbnb
29-03-2014, 03:21 PM
I have a brand new 3 door 134a refrigerator. I accidently purchased a new 404a condensing unit. Can i run the fridge with the condensing unit using the 404a without a prob or should i use r134a in the 404a condensing unit instead? Or is there a way to make the fridge components 404a compatible?? Thank you all in advance. All answers appreciated.

NewmanRef
29-03-2014, 07:03 PM
You definately don't want to use R134a with your r404a condensing unit. You could do mods to your cabinet to suit r404a but I would suggest you just swap your condensing unit for an r134a equivalent.

Universalbnb
29-03-2014, 07:31 PM
Thanks NewmanRef!! Not sure if ill be able to swap out so im trying to figure out worsr case solutions. What would happen if i just ran the 404a? Would the cabinet still cool efficiently? Also how tough would the mods to the cabinet be in terms of time and money? Thanks again! All help appreciated!!

monkey spanners
29-03-2014, 07:46 PM
There is nothing inherent in either refrigerant to stop them being used in either a freezer or a fridge. BUT, the choice of refrigerant and equipment selection would effect efficiency, running cost, and possible reliability.

You need to find the duties for the various components, the evaporator would likely be ok on either refrigerant so long as the expansion device is matched to duty and refrigerant type.

Also with the compressor, one that would run a freezer on R404A would likely suit a fridge on R134a, but not vice versa, its to do with the ratio of motor power to cylinder capacity. Smaller hermetic euipment is less suitable for running out of manufacturers specification.

So the short answer is we need more info. (though i'm in the uk so will not likely be familiar with your equipment)

Universalbnb
29-03-2014, 11:27 PM
Thank you Monkey Spanners. Not really sure about duties but i have 3 mediums and 1 low. I bought 3 fridges and 1 freezer box with remote condensor units. I ordered the cabinets online but bought the condensor units local. The mediums are 3/4 h.p. and the lows are 2 h.p. all the cabinets including freezer are rated for 134a. All the condensors units are rated for 404a. I do have a refridgeration person for installation who is telling me he can mod it but id like the specifics on how its going to affect the overall performance and what exactly would need to be done. Doing my homework and trying to prevent headache down the rd and im not sure whether this guy is yessing me to death just to get the work. I am certified in auto a/c and i know components are similar to an extent. I know that when we convert the old r12 systems to r134a its a simple retrofit kit and new gas. If its that simple for refrigeration i dont mind but i dont want to do it if its more of a rig job than something that is an accepted commonplace practice. Thx again for all info given.

monkey spanners
30-03-2014, 02:44 PM
Your tech would need to check the duty of the evaporators in the cabinets, and compare the btu's to what the condensing units are rated for. There may be a derating factory to apply to the evaporators duty when changing refrigerant type.
It may only take a change of txv model to make the cabinets R404A compatible.

It is not quite the same as with R12/R134a in cars as the oil type is the same with R134a and R404A, the main problem is the completely different pressure the two refrigerants run at, they would have different mass flow rates too. Whereas R12/R134a are very similar to the point it would be difficult to tell them apart.