Trouble with 404A system...Please Help

[wllmwallace]

Have a Russell brand refrigeration unit (walk in freezer) 5.0 tons, with a Copeland Scroll Compressor, liquid injection type cooling system. It runs on Honeywell brand 404A refrigerant.

Here's the problem:

Refrigerant seems to be breaking down, pressure's throughout the system rise approx. 100lbs more than they should. Temperature/Pressure check on refrigerant in standing drum, show refrigerant gains 100 lbs more than the chart says it should be. This break-down occurs 4-7 days after running, and just shows up immediately/overnight with no warning.

System never runs into a vacuum, oil has been changed several times in the compressor using POE Oil. Refrigerant in system has been changed 5 times. Each time refrigerant has been changed system has been vacuumed down to 400microns.

Question I have is has anyone had a problem with this refrigerant breaking down, and what could be the cause. Have a new compressor coming and wanted to know if I should convert system to another refrigerant type, or what I should do. Any more information, please PM me, and I can get a phone number to you if you could help me over the phone. My e-mail is: wllmwallace@yahoo.com (wllmwallace@yahoo.com) Thanks for ANY help with this.

[Gary]

The refrigerant is definitely NOT breaking down.

Sounds like non-condensibles to me. Possibly there is a section of the system which is not being evacuated.


Temperature/Pressure check on refrigerant in standing drum, show refrigerant gains 100 lbs more than the chart says it should be.

Are you saying that you removed refrigerant from the sytem into a drum and the pressure is reading 100psi too high?

[wllmwallace]

"Are you saying that you removed refrigerant from the sytem into a drum and the pressure is reading 100psi too high?"

Yes.

As far as a section not being evacuated, been looking at this problem, and entire system is being evacuated. The problem isn't gradual, it runs at -7 F for about a week, then has the pressure problem overnight.

[wllmwallace]

Thanks Gary for your post. I just shot you an e-mail about this.

[Gary]

The drum test confirms that this can only be air in with the refrigerant... and this is only possible if the air is sucked into the system, but the refrigerant does not leak out.

IOW, there would have to be a large leak only when the system is in a vacuum.

[Brian_UK]

I wonder whether you are suffering from the system being tampered with.

[al]

or as honeywell are finding out,the chinese have copied the gas incorrectly,have you a non oem batch???

al

[Gary]

For a full evaluation we would need the following:

Air temps entering and leaving the evaporator.

Air temps entering and leaving the condenser.

High side and low side pressures.

Liquid line temp at the receiver outlet.

Suction line temp at the evaporator outlet.

[cadwaladr]

it may sound stupid but are you charging this system in the liquid phase and i hope not the vapour phase years ago heard of some bottles marked incorrectly/make sure all the mag valves are lifted when evacuating