My typical day at 85 looking forward to 100 and my next challang

[Richard Kollmann]

Today my email Q and A

Question Richard,
Lot's of great info you've provided on marine refrigeration! Much appreciated.
We recently acquired a 1989 sailboat with the 110v Grunert system. It's time to pull it out and get into the 21st Century with more efficiency.
Currently spending more time in tropical climates, but still looking for direction on keel cooler system versus air cooled. Wouldn't water dissipate the heat better than air? Are the FrigoBoat products truly more price than value and maintenance heavy?
Our boxes are separate and large. It's an Alden 54'

Answer:
The difference in Tec knowledge today and 1989 on twin refrigerated boxes in a 54 ft boat has changed very little unless you are prepared to reduce the box sizes to except 12 volt refrigeration. In those days a 54 ft boat had a generator capable of supporting large box refrigeration. Let me know the inside dimensions of each box and approximate amount of insulation on all six sides and I will estimate what your equipment needs will be. I also need to know what Latitudes you expect to operate the boat.

Water cooling boat refrigeration is essential when compressor sizes are over 1/3 HP but generally unfriendly application for small 12 volt refrigeration. Water does dissipate heat better than air but difficult to control water temperature. The amount of heat retained in refrigerant is as important as the heat removed in order too maintain a reasonable pressure differential across refrigerant flow control device.

As to keel cooler condenser over air cooled condenser the cooling medium is critical to prevent compressor cooling temperature damage especially for keel cooler systems with extended cruising in tropical climates.

Another message on this forum this morning of a keel cooler system with refrigerant flow problem.

Q. after noise stops and listening 15 min. is there a short time where hissing starts again for a short time?
A. yes, intermittently I can hear a slight gurgling sound for only a few seconds. Frost appears on copper tubing at the evaporator

Q. how old is system.
A. unknown, came with the boat. I've owned her for 2 1/2 years. She is a 1990 make, but I don't think system is OEM.

Q. How much time in the tropical weather
A. The previous owner had her for approx 9 yrs. So, Fla weather 11 yrs

Q. Has anyone tampered with refrigerant.
A. No. I live aboard and left for 6 months and she was locked up for the duration. Before I left I emptied the unit, defrosted it, and turned it off. When I came back, I turned it on and am getting what is described. It has been working fine for the two years prior.

Q. When compressor is running can you determine how many amps it is showing?
A. 4.2 amps

No oil residue at any of the connectors. When the system is initially energized and gurgling is heard, the copper tubing at the evaporator frost up and part of the evaporator is cooling[/QUOTE

Add R134a] refrigerant to raise amperage very slowly slowly slowly till amperage is stable at 5.5 amps and do not overcharge. Let it run cycling for at least 12 hours then describe frost cover on surface area of evaporator and length of frost on return line towards compressor.

Hi Richard, I did as you suggested and added refrigerant until the amperage is 5.5 amps. Still no workie. I am much of the same cause and effects as s/v xx wrote about and that you responded to in CF "Bizarre Frigoboat behavior" on 15/02/2011.
After a few minutes of the compressor cooling off the evaporator it will shut off. I can heat the capillary tube up on the back of the evaporator and the compressor will continue to cycle on and off. I've tried tapping on the tubing and wiggling the tubing to hopefully dislodge/melt any foreign matter that might be in the system.
Do you have any suggestions or a place where I can find instructions on how to evacuate the system to suction the particulates out?




ANSWER: The information is still confusing when trying to understand why commpressor stops running with only 5.5 amp current draw. Did compressor stop because of an overload amps or because of refrigerant flow blockage? We really need an answer to this. If this compressor is a BD35 or BD50 does it have a trouble LED flash code signal?

Once we rule out compressor stopping question It does seem to indicate a refrigerant flow problem either moisture in system freezing and thawing in capillary tube or contaminated oil partials blocking cap tube.
It is easy to identify moisture freezing and thawing if compressor is running continuously as evaporator temperature will be around 33 degrees F and covered with cold condensation.
Frigoboat keel cooler systems operated in warm waters for long periods with out adequate cooling generate contaminants that will block capillary tubes. The problem with Frigoboat keel cooler units is the filter dryer intended to collect solid material before it interiors cap tube is located on the low pressure side of system.

Frigoboat normally recommends replacement of evaporator which includes the cap tube and I also recommend installing new addition filter before cap tube. I do not believe the cap tube can be cleaned out many have tried and failed. I have even seen evaporators replaced three times and still had to replace complete system.

Finally if compressor will not run now continuously keep letting out small amounts of refrigerant with system turned of, say for 3 seconds and try to get it to run. If compressor will not run turn off power and let out 3 seconds of refrigerant. Now with compressor running normally check for moisture in cap tube before believing there is a catastrophic problem.

I hope the compressor not continuing to running has nothing to do with a electrical resistance in boats refrigeration wiring and do not tell me you check the voltage with a volt meter instead of following my instructions to bypass all boat refrigerator wiring.