Waeco Refrigerator unit

[landonshaw]

Just purchased a new Waeco CU-85 (8.8 CU Ft) compressor / condenser and a L shaped evaporator plate to replace the old Frost Mate (Adler/Barbour (Waeco) 6.6 CU FT) that is on the boat. The L evaporator plate did not fit in the refrig so exchanged it for the flat plate, I believe VD05. Reading the instructions it sounds like the final turn on the connections pierces a cap in the coupling there by releasing the refrigerant that was added at the factory. I believe this is on the condenser side.
Question: When I replace the old compressor with the new, am I able to connect the new unit to old evaporator without having to add more gas? This would save purchasing and installing the new plate. Will the refrigerant in the L shaped old evaporator remain in the tubes after disconnecting it from the broken but not leaking old compressor?
Will the Frost Mate L shape evaporator work with the Waeco CU-85. 8.8CU Feet, Frost mate was a 4.6 CU Feet unit.
Is the gas the same in the new compressor (R134a) and old evaporator (HFC134), does it matter?

[landonshaw]

The old Frost Mate unit was a 6 CU ft unit

[Richard Kollmann]

A WAECO CU85 RV type condensing unit with BD 35 compressor would not be my choice for a tropical climate unless box is very small. The general creative statement that indicates it will refrigerate an 8.8 cu ft box I think would only apply to northern climates at standard day (70 degree F.) temperatures. Small VD05 evaporator also will limit the variable speed BD35’s capacity even more. Information I have on your old Adler Barbour’s Frost Mate system is that it uses the BD 50 compressor condensing unit and 30% larger capacity than CU85 condensing unit. A 4 cu ft box would be the largest size refrigerator for a BD35 compressor in the tropics unless all one is looking for is a drink cooler.

Frost Mates advertising a BD 50 condensing unit could handle a 6 cu ft box was a fair representation for true refrigeration in a hot climate.

There are 4 different types of pre-charged line connectors If your old Adler Barbour unit had the BD50 compressor line connectors would probably have been new type self piercing. Once self piercing line is disconnected again refrigerant is lost and moist air will inter system requiring deep vacuum dehydration and re-servicing.

If 134a gas is pure with no additives it should be OK to mix with another pure 134a refrigerant containing no additives.


.

[Bash]

The short answer is "no." You would not only lose refrigerant, but contaminate it as well.

[redhead]

These A/B or waeco reefer units are well made and hold up well. Now to your situation, once the factory seals are pierced its a pro's job, due to air contamination inside the sealed refrigeration system. If you have already broken the system open, try to seal the ends with clean electrical tape,A.S.A.P. and find a refrigeration man or lady with a vacuum pump.
Best of luck

[landonshaw]

Thank you for the comments. I have not pierced the connections. I was hoping, although did not think it would work, to only replace the compressor and leave the plate in place. It looks like once I disconnect the connectors both the compressor and the plate gas can escape thus letting moisture in. The only fix then is to have the plate once connected to the new compressor refilled by refrigerator expert. There is also a possibility that moisture could enter the system causing harm if this was done.
Is this true?

[landonshaw]

The flat plate fits into my unit so will change both the compressor and plate. Originally trying to save $179US, but after spending $700, another 2 doesn't matter and it is being done correctly.

[Richard Kollmann]

landonshaw Very small amounts of moisture in your system over time can cause chemical action acid that will corrode aluminum evaporator from the inside out. Large amounts of moisture can form ice blockage stopping refrigerant flow.

What prompted the decision to replace Adler Barbour condensing unit as it will outlast more than one evaporator?

[landonshaw]

We were out and it first over heated enough to melt a soldering point where the power attaches. Once repaired it sporadically worked for the rest of the trip. Three months ago I had a refrigerator technician on the boat to check the system and he said it ran as it should although it is very tired. He suggested at that time not to replace but run until it failed. He charged me a minimal amount for the hour and a half review and he also added a small amount of gas to the system. I think it just failed.

[Richard Kollmann]

After twenty five years of working with hundreds of Danfoss BD compressors this is the first time a service tech describes one as it “is very tired”. Condenser cooling fans do get tired but never heard of a tired BD compressor. A poor power wire connections will cause connection to overheat damage and not trip its 15 amp circuit breaker. Any one can determine if a small capillary tube refrigerant fed evaporator needs more refrigerant without tools or gauges. Too much refrigerant can damage electronic control module if it repeatedly recycles compressor do to high operating temperatures. Well I guess it is too late to correctly troubleshoot the Adler Barbour unit now?

[landonshaw]

Yes too late. here in Grenada we have very few qualified techs, much less the parts to fix things. Thanks for your help.

[landonshaw]

Finished installing the new refrig. It was very easy, took only a few hours to take out the old and install the new. During the installation, I thought of purchasing some tube installation like the type to keep pipes from freezing and putting it on the tubes running from the compressor to the refrig. Has anyone else done this? What results did you notice?

[Richard Kollmann]

Mobile refrigeration systems like the one you purchased depend on compressor cooling provided mainly by super cooled refrigerant gas returning from evaporator at around 60 degrees F. It is also important that gas returning to compressor not be saturated with liquid refrigerant that can damage compressor. Frost on return line outside refrigerator returning to compressor would indicate either evaporator is too small for the amount of refrigerant planed for this system’s design in a hot climate. When excessive frosting is present on return line evaporator refrigerant flow is excessive wasting energy. Trying to correct this problem by reducing refrigerant volume is a mistake because in cooler weather additional refrigerant needs to be added again.

As far as adding insulation to return line outside refrigerator you will not know if there will be frost till system has run a day or two. Manufactures of these systems do normally supply a three ft section of pipe insulation to install on line outside box because they are aware that changes in condenser cooling medium temperature will result in evaporator superheat changes. With a perfectly fine tuned system there will be a few inches of frost on return line do to heat conduction through metal from evaporator to copper line at times, but never more than a few inches of frost. If frost is excessive you may be able to reduce it by slowing BD35 compressor’s speed or placing a small 10 Cfm muffin fan blowing air on evaporator increasing its efficiency and decreasing superheat causing frost on return line to move back into evaporator where heat transfer is supposed to occur.

[landonshaw]

Thanks for the comments. My tubes are not icing up, there is just a lot of condensation dripping off of them. I was thinking that the additional insulation might help to prevent this.

[Richard Kollmann]

Condensation on refrigerant return line to compressor is not as bad as energy wasting frost on that line. Manufacturers that design for tropical climates, like where you are in the West Indies, install a section of tube insulation on return line outside refrigerator to improve performance and reduce unwanted condensation inside boat. They also run refrigerant flow control capillary tube inside and around return line several times to improve liquid refrigerant sub-cooling. To compensate for extreme warm climate conditions refrigerant lines are either clamped together or spot soldered together every two feet. With these two lines touching allows heat to be absorbed by return line eliminating condensation. It is said that “Sub-cooling can have a dramatic effect on the capacity of a refrigeration system - as a general rule; a 1% increase in refrigeration capacity can be achieved for every 2 degrees of liquid sub-cooling”.

Tapping your lines together at a few spots and adding an additional 4 ft of tube insulation over bundled tubes should eliminate condensation problem.