Originally Posted by jt11791
On my boat I have two BD50s running separate boxes. They both have merlin speed controls and keel coolers. They work well, holding the boxes at the set temp and cycling as expected. My concern is that the compressors fail the palm of the hand test. They both are hot when running, typically 55C to 63C. I just checked the one that is running right now and it is at 55C and is drawing 2.5 amps (merlin shows one flash indicating the lowest speed). The two compressors are mounted together in a small space. Sometime back I added a small fan to improve airflow in that space. I don't know what more I can do to improve the situation, maybe some way to add a heatsink?
Should I worry about the high compressor temp? Or just be happy that the beer is cold and the ice is hard.
Jt 11791, I prefer to provide facts in answering questions about popular pleasure boat live aboard refrigeration
. These ice box conversion refrigerator
companies do not design the units they sell to be compatible with all boaterís different requirements which means design flaws may show up some time later. Hermetically sealed compressors like the danfoss 12/24 volt BD were designed for only air cooled condensing units that rely on a portion of condenser fan air for massive excess compressor heat disposal. Primary compressor cooling
is achieved by sufficient refrigerant flow and temperature returning from cold evaporator. Danfossís poor condenser cooling
protection is determined by the amount of current flowing between Small plus and F terminals of their control module to operate additional compressor cooling ,module cooling and condenser fans. None of these are connected on Frigoboat keel cooler
units to over heat module safety
Compressor temperatures that may exceed 55 degrees C (130F) for an extended time should be investigated, Louieís attempt's of sick humor
jokes to sell his refrigeration
can again be ignored. I have followed designs of mobile refrigeration especially in boats for forty years. The last time I check all my hard drives for system outages on keel coolers there were over 200 messages related to Frigoboat. These systems must outsell all the other popular brands, I recommend a lot of them but since 2004 and my meeting personally with their design engineer
I recommend their inline secondary fan cooled condenser when operation is expected to be used in tropical waters or when the boat refrigeration is used on the hard
out of water
. I still recommend a separate 40 to 60 Cfm fan blowing air over compressor when seawater temperatures are above 75 degrees F. Any time these compressors run at maximum speed and load danfoss recommends module fan cooling.
Jt11791, Your reported amp draw of 2.5 amps and 55 C indicates a problem You also indicated compressor cycle times were OK, normal. I am no longer able to run my test stands to duplicate your reported conditions but a BD50 with almost no refrigerant in it will draw around 2.2 amps at 2,000 Rpm. Another confusing fact is heat and compressor temperature and how high and low energy consumption
I am left with questions: if these are freezer
performance figures what are the refrigerator
Can you report the approximate temperatures of refrigerant lines going to each keel coolers and each line returning? I would expect lines going to each keel condenser would be rather warm HOT. Lines returning from the keel condenser have a temperature a little warmer than your body temp, not much more than 115 degrees F except in 90 F seawater.
There have been a number of Frigoboat catastrophic failures of these systems requiring complete system replacement three or four on this forum. As I recall
they all operated longer than a year in tropical waters. The first sign of a problem was lack of evaporator ice cover and decisions made to add refrigerant without confirming current amperage draw. Adding refrigerant increased oil
contamination .One boater on this forum that I contributed to the oil overheating
compressor oil desistor, ended up with a BD50 current draw of 18 amps. The complacent system with a BD80 water
cooled normal condenser did not perform as well as the keel cooler
. I was shipped the old capillary tube complete for analysis. .