Frigoboat Keel cooled unit: Help!

[Hobiehobie]

We are at our refrigeration wits end! We have a 2007 era frigoboat keel cooled system. One for fridge and one for refrigerator. Both have caused mild problems in the past usually to do with moisture in the system that has been easily fixed. But this season we returned to the boat in Trinidad after 6 months on the hard to discover that the fridge was not performing as last season. Basically it takes about an hour or more to drop one degree at full compressor speed (6 bars) and pulling about 8 amps. This draw is fine when plugged in but on the hook it eats at our batteries as the compressor is on full draw for 12-16 hours a day. By comparison the freezer takes 6 to 7 minutes to drop 1 degree at 2 to 3 bars of compressor speed, 3-4 amps. Is only on for a couple of hours a day.

We have had many expensive hours of the our Antigua-based Frigoboat service agent crawl all over the unit. Changed all filters, vacuum pumped for 24 hours, tested thermostat, tested compressor function, gas charge ok. All good. Insulation seems to be fine. Keel plate clean. plate in fridge has even frosting and healthy gurgling sound, suggesting that is not blocked. Fridge does get down to set temp (38 F) eventually but the power required to get there and stay there even with infrequent use is not sustainable for us unless we run our generator 24/7.

Anyone have ANY idea what might be wrong with the system? (BTW compressor, thermostat and controller are all about 1 year old, all seem to be fully functioning. Anyone had a similar experience and fixed it?!

[Richard Kollmann]

You describe a common problem with Frigoboat keel cooler system operating long periods in tropical conditions. High compressor temperatures will cause contamination eventually requiring system to be replaced. Frigoboat offers several solutions like replacing evaporator which includes plugged cap tube, installing a filter dryer in the correct location before cap tube instead of after evaporator. Normally after spending twice what a new system would cost others have wished they had bought another type system.

When these systems are lightly loaded in small boxes or operated seawater temperatures below 80 degree F compressor and system failures can be avoided. Keel cooler system life in tropical waters is even shorter if compressor has ever run while boat is on the hard. Frigoboat's final solution to oil contamination caused by high compressor temperatures is to install an inline fan air cooled condenser, it is too late for that once complete system is contaminated.

The beginning signs of over heated contamination is refrigerant is added beleaving loss of refrigerant. Excess refrigerant shows up as higher than normal amperage and unless refrigerant flow is completely blocked box temperature will get cooler. This flow condition over time will get worse and solution has been each time to add more refrigerant/pressure. I know of a system drawing 18 amps to cool box before it was replaced.

[Hobiehobie]

Richard. Thanks so much for that. Our technician is installing a new much larger evaporator plate with plugged cap tube and filter dryer before cap tube. Fingers crossed

[Tupaia]

"Both have caused mild problems in the past usually to do with moisture in the system that has been easily fixed" How?

I have two of these one fridge one freezer. They have run flawlessly almost 24/7 for close to 20 years mostly in the tropics. I had similar issues early on with one unit. The conclusion was that the driers are woefully inadequate and I replaced one oil contaminated evaporator plate and the driers on both units with ones from air conditioning units. The original ones are about the size of a life jacket CO2 cyclinder the replacements are about the size of Campbell's soup cans.

[pcmm]

Originally Posted by Richard Kollmann

You describe a common problem with Frigoboat keel cooler system operating long periods in tropical conditions. High compressor temperatures will cause contamination eventually requiring system to be replaced. Frigoboat offers several solutions like replacing evaporator which includes plugged cap tube, installing a filter dryer in the correct location before cap tube instead of after evaporator. Normally after spending twice what a new system would cost others have wished they had bought another type system.

When these systems are lightly loaded in small boxes or operated seawater temperatures below 80 degree F compressor and system failures can be avoided. Keel cooler system life in tropical waters is even shorter if compressor has ever run while boat is on the hard. Frigoboat's final solution to oil contamination caused by high compressor temperatures is to install an inline fan air cooled condenser, it is too late for that once complete system is contaminated.

The beginning signs of over heated contamination is refrigerant is added beleaving loss of refrigerant. Excess refrigerant shows up as higher than normal amperage and unless refrigerant flow is completely blocked box temperature will get cooler. This flow condition over time will get worse and solution has been each time to add more refrigerant/pressure. I know of a system drawing 18 amps to cool box before it was replaced.

Richard,

You mention adding a filter/dryer before the cap tube. Is this a component that needs soldering in, or is there a unit that can be installed using the "quick connect" fittings? I have an older frigobot unit that for the most part works well, but Its had the occasional issue where the compressor doesn't want to start. I likely have a replacement of the compressor in my future.

[svJasmine]

I had a leaking Keel cooler and replaced the condenser with one from a super cold machine with a fan. Vacuumed it out and has been working for years.

Shame the keel cooler doesnt work any more. it was a bit more efficient that way.

[Coolerking]

Originally Posted by pcmm

Richard,

You mention adding a filter/dryer before the cap tube. Is this a component that needs soldering in, or is there a unit that can be installed using the "quick connect" fittings? I have an older frigobot unit that for the most part works well, but Its had the occasional issue where the compressor doesn't want to start. I likely have a replacement of the compressor in my future.

There are 2 types of liquid line filter driers that are used in this situation, flare and solder. There are others, but they are not the type you need in this case.

None of them come with QD's that I'm aware of.
Most of the driers I add on these small systems are sizes 032/052, some solder (referred to as ODF in the industry) and some have 1/4' male flare ends and require you to get flare nuts and properly flare the tubing with the correct tool.
They are not bi-directional, so pay attention to the flow direction indicated on the body of the drier.
You can use a quality soft solder and a propane torch for this as well, instead of a silver solder that requires an oxy acetylene braze set.
Care must be take to not flood the solder so much as to block the line.
Very little is needed.

[Richard Kollmann]

Originally Posted by Hobiehobie

Richard. Thanks so much for that. Our technician is installing a new much larger evaporator plate with plugged cap tube and filter dryer before cap tube. Fingers crossed

I have tracked these Frigoboat failures for twenty years and contamination caused by operating this small compressor with Ester oil at too high a temperature for long duration will cause deposits in capillary tubes. Any design application that pushes the original compressor manufactures specification envelope can at some point cause failures. Of the large number of keel cooler systems sold only a few are exposed over time to excessive oil temperatures. Once these crystals for lack of a chemical term begin to restrict flow their does not seem to be any solution except to replace complete system. Installing larger filter before capillary tube and replacing complete evaporator assembly is generally the first step and in a couple cases has produced temporary results. But to replace evaporator a second time or try any other solution wastes time and money.

Now that you have added filter and replaced evaporator as Frigoboat web site recommends record normal amp draw of unit for future reference. Later flow blockage will show up to look the same as low on refrigerant but when you add refrigerant to adequately cool evaporator normal amperage will be much higher.

If all these systems were only sold to boaters in tropical climates there would be design changes, installing filter in correct place, eliminating Oring seals in line connectors and providing adequate compressor cooling.

[Hobiehobie]

All great information and sage experience. I can report that installing a new larger evaporator plate and filters in the suggested location seems to have solved my problems...only couple of thousand dollars of materials and labor! When I get my boat back to the US I will probably replace the front door and top door seals. The fridge and freezer still draw a large amount of power but not more than the published expected draw for the compressors. Boat is set up to feed these power hungry components, but I will work on insulation and seals to see if I can keep more of the warm out.

Thanks for all advice and comments.