converting from r12

[edd1e]

just been to my dads pub as he has a walk in fridge in the cellar that was not working. After diagnosing it has having no gas i then leak checked the unit and repaired the leak but found it to be running on r12. should i chrge unit with r134a and will i have to change the expansion valve as it is a danfoss tx2 r12. not up on these fridges as i normally work on trasport stuff. your help would be much appreciated cheers eddie

[andywill]

You can get R409a as a drop in replacement for R12 with no changes. A long term soloution would be R134a but yes you would have to change the TEV and also change the oil and flush the system. Hope this helps

[mcunliffe4]

you could try r413a, make sure you change the drier. hope this helps, make sure you vac out before charging

[djbe]

I tend to use R413A as well, or sometimes called isceon 49.

works good as a drop in, might have to adjust the superheat a bit, generally charge 10% less than recommended charge and expect flashing in the sight glass.

[hot chilly]

best choice is the long term retrofit with r134a and poe oil but this takes time and about 3-4 oil changes to get less than 5% mineral oil in the mix also have to change expantion device and dryer

[Dieppert]

I have converted many systems from r-12 to 134a, as mentioned above you must change the oil to POE, and change the oil at least 4 to 5 times to get the mineral oil down below the 5 % mark, a refractometer is good for this, it will tell you when your safe , change your driers, POE will break loose particles in the system, as far as your TXV, leave it alone, the same txv will work with the 134a , do check your txv for a removable inlet screen, if so, clean it after system runs a few days, set your super heat