Changing the old r22 chiller in what?

[texanul]

I am about to change an old MTA chiller with r22 refrigerant with a new refrigerant and i am no`t decided what to do. Should i put the new r417 refrigerant and no`t changing the oil or what should i do? Please help me with some advice. Best regards!

[Brian_UK]

Read the DuPont guidelines for the retrofit....

http://www2.dupont.com/Refrigerants/en_GB/assets/downloads/k10921_MO59_uk.pdf

[texanul]

The problem is Dupont say is ok only for the systems <15 kw and my chiller is much bigger. What should i charge than? Nobody did this before? Please help with some advice.

[james10]

Mo29 which is similar to 417a which is also from dupont they say you don't need to change the oil but you do if you are using recip compressors use emkrate 68 ester oil also allow for extra gas I did a retrofit with this gas and needed twice as much as the original charge

[texanul]

I don`t know what to belive now: they say the charge should be 95 percent of original charge and now you say i should 2 the charge. Should i change the tev?

[FRIDGE]

I had this trouble before with a 3x 6 cylinder recip chiller.

the key is to ensure you recover all the oil from the system, especially if its old and had taken a good beating over the years. excessive heat breaks down oil and it becomes like water and doesn't mix properly with the refrigerant, if this oil is sitting in the evaporator or condenser you will have problems as MO29 is not as good as R22 when is comes to oil miscibility.
So make sure you recover all the old oil and wash out the system before you carry out retrofit. otherwise you will have low back pressure problems and subsequent oil return problems.
You may also have to tweek expansion device.

Some people carry out retrofits without doing all that, and it works so it varies from system to system and also depends on plant history. is it a water cooled machine? has it had a history of water flow problems and HP trips? If so then chances are the old oil is not so good.

[Fri3Oil System]

Hi,

Ask Du Pont what would happen if your condenser is above the compressors. They might not recomend that gas without an oil change.

If you do not make any oil change, you will sooner or later have oil return problems. This could happen in a period of minutes, hours, weeks o months. We have observed different cases.
www.fri3oilsystem.com/retrofitcase.zip (http://www.fri3oilsystem.com/retrofitcase.zip) In this case, for instance, they run with R422D for a year and a half, and then they had to change the gas, as they had no oil in the compressor.

Regards,

Nando.