Fridge troubleshooting - advice requested

[OzeLouie]

Originally Posted by Richard Kollmann

No, you can not unlock liquid moisture from POE Ester oil the ways we did for years with Mineral refrigerant compressor oil and Alkabenzine oils by several dryer replacements. If you search this problem on the web you will find some who say water droplets in POE oil can not be removed. Thirty inches of vacuum reading on a refrigerant gauge at 70 degrees F or cooler is not likely going to boil moisture into a vapor that can be extracted by a pump. Experience shows that super dehydration using a additional Micron gauge drawing vacuum below 200 micron will vaporize moisture from POE oil. One inch of vacuum equals 12,000 microns. At 200 micron and complete system temperature at 100 degrees F for 4 hours on small systems I am successful in getting all moisture out. Most refrigerant two stage vacuum pumps claim low vacuum of 25 to 50 micron but I have never seen readings below 100 micron. Without seeing micron gauge readings you can see why some techs leave pump running 24 hours. With a system much below 70 degrees it is going to be dificult to remove moisture.

Good response Richard, but finding a tech with a two stage vac pump, a digital vacustat and the time required, could be a problem let alone the costs involved!
In some situations it would be preferable, cheaper and quicker to change the compressor oil if the condensing unit can be easily disconnected and up-ended for draining. Thousands of oil changers were done on similar systems with R12 and Suniso oil were converted to R134a and POE oils so very do-able

[Richard Kollmann]

Originally Posted by OzeLouie

Good response Richard, but finding a tech with a two stage vac pump, a digital vacustat and the time required, could be a problem let alone the costs involved!
In some situations it would be preferable, cheaper and quicker to change the compressor oil if the condensing unit can be easily disconnected and up-ended for draining. Thousands of oil changers were done on similar systems with R12 and Suniso oil were converted to R134a and POE oils so very do-able

I no of no manufacturer of systems using Danfoss BD compressors that recommend your Dehydration process. I tried to do this after this was recommended on another thread. Removed unit turned condensing unit upside down. Luckily there was a service port near the top of compressor. Of the 12 ounces of oil maybe 8 came out over night the rest may have been in the other parts of system with oil traps I could not drain.

[OzeLouie]

Originally Posted by Richard Kollmann

I no of no manufacturer of systems using Danfoss BD compressors that recommend your Dehydration process. I tried to do this after this was recommended on another thread. Removed unit turned condensing unit upside down. Luckily there was a service port near the top of compressor. Of the 12 ounces of oil maybe 8 came out over night the rest may have been in the other parts of system with oil traps I could not drain.

Well you do now Richard! We did lots of oil changes this way when R12 was banned and the requirement was to change the oil to POE prior to filter change, evacuation and recharge with R134a. Very common practice here in Oz, otherwise how do you change the oil to conform with the then regulations or save a badly contaminated comp? Never had any problems with any such oil changes I did and there were many.
This method is only possible where the condensing unit is accessible.

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[Richard Kollmann]

It is one thing to convert Mineral wax free oil to Ester POE oil. We will see if anyone having moisture in POE oil will risk their refrigeration system. Your picture is of a Adler Barbour CU200 does Demedic approve of your oil change recommendation?

[OzeLouie]

Originally Posted by Richard Kollmann

It is one thing to convert Mineral wax free oil to Ester POE oil. We will see if anyone having moisture in POE oil will risk their refrigeration system. Your picture is of a Adler Barbour CU200 does Demedic approve of your oil change recommendation?

Yes, assuming you are referring to Dometic.

Here below is the response we got from Adler Barbour 26/06/2018 when this oil change process along with diagram, was presented to them and they were asked to comment...

"Hello Jack, this procedure should work, you are leaving a small amount of pressure in the system to assist in getting the oil out. The way I read it, you are disconnecting the evaporator during the process. The correct amount of oil, equal to what you removed goes into a container that you would use to add the new oil."


.

[Richard Kollmann]

Originally Posted by OzeLouie

Yes, assuming you are referring to Dometic.

Here below is the response we got from Adler Barbour 26/06/2018 when this oil change process along with diagram, was presented to them and they were asked to comment...

"Hello Jack, this procedure should work, you are leaving a small amount of pressure in the system to assist in getting the oil out. The way I read it, you are disconnecting the evaporator during the process. The correct amount of oil, equal to what you removed goes into a container that you would use to add the new oil."


.

I have been to Domedic engineering factory near my home before I retired. I am surprised at his or her answer when it comes to Moisture in POE oil. Didn't they ask about moisture trapped on Field coils and in the other parts of system? Especially in the aluminum evaporator's circular oil accumulator section designed to trap liquids.

[OzeLouie]

Originally Posted by Richard Kollmann

I have been to Domedic engineering factory near my home before I retired. I am surprised at his or her answer when it comes to Moisture in POE oil. Didn't they ask about moisture trapped on Field coils and in the other parts of system? Especially in the aluminum evaporator's circular oil accumulator section designed to trap liquids.

Obviously if the amount of oil drained indicates excessive retention then flushing would be the next step.

Richard, neither deep evacuation you describe nor oil change I described alone will guarantee recovery of the system to 100% clean status.

The following assumes the gas leak has been repaired...And a proper (NOT spun copper strainer) filter dryer (like a Sporlan F032 or F052) is readied to fit mounted vertically before entry to the capillary or TEV.

Evacuation: Unless evacuation pump lines are connected to both the low and high sides of the system (and not just the low side, suction) then it is highly likely that all of the high will not be evacuated at all! The other issue regards relying on evacuation alone is not having access to inspect the contaminated oil for evaluation and there is no way of knowing the success or otherwise of this process albeit highly likely to be successful if the process is strictly followed especially relating to two stage vac pump ability, low and high side evacuation with heat applied to the entire system, digital vacustat monitoring and eventually a proper filter dryer fitted.
Down side is the time/ cost required for this process and no guarantee of 100% success.

Oil replacement (if physically possible): As you stated there will be a small amount oil left in the other areas of the system. As a practice if the amount drained is approx. 90% of the quoted charge then that is considered acceptable otherwise the system can be flushed. The drained oil can be inspected and consideration made as to if flushing is warranted. This is usually a quick and inexpensive remedy still requiring some evacuation and a new filter dryer but also with no guarantee of 100% success.

The best option is a combination of both processes if possible.

[Richard Kollmann]

Ozelouie, Your school book method of removing moisture from POE refrigerant oil systems sounds good but is not practical for a DIY boater. Super dehydration is far less expensive and simpler. All a boater or local technician needs for Super dehydration is a servicing gauge set, a hair dryer to increase moisture phase change temperature, and a refrigerant vacuum pump with clean oil in it.

[OzeLouie]

Originally Posted by Richard Kollmann

Ozelouie, Your school book method of removing moisture from POE refrigerant oil systems sounds good but is not practical for a DIY boater. Super dehydration is far less expensive and simpler. All a boater or local technician needs for Super dehydration is a servicing gauge set, a hair dryer to increase moisture phase change temperature, and a refrigerant vacuum pump with clean oil in it.

My "school book method" taught me how to do these things properly and unless the process I described in my previous post is followed specially regards connecting 2 stage vac pump to both high and low sides of the system, monitoring with a digital vacustat and fitting a proper filter dryer, then don't expect a permanent remedy. And yes, a job best left for a qualified, well equipped refrigeration tech to perform.

[Richard Kollmann]

Originally Posted by OzeLouie

My "school book method" taught me how to do these things properly and unless the process I described in my previous post is followed specially regards connecting 2 stage vac pump to both high and low sides of the system, monitoring with a digital vacustat and fitting a proper filter dryer, then don't expect a permanent remedy. And yes, a job best left for a qualified, well equipped refrigeration tech to perform.

If it were physically possible to accomplish your procedure while complete system is installed in boat, how many man hours would it take to dehydrate system and re commission this system? I agree it would require a Qualified well equipped refrigeration technician. In the USA a qualified tech gets $90 to $125 per hour, don't these requirements rule out the boat owner from doing the work him or her doing the work their-self as I recommend?

I believe with today's synthetic oils super dehydration is less expensive with fewer risks and allows the boat maintenance person to free a refrigeration system of moisture. Two stage vacuum pumps are available from rental stores or small CFM units are available from Robin air or Harbor Freight. The pump used must be ratted down to at least 50 micron. Used pumps must have new oil change with correct oil recommended by manufacture.