Today was refrigeration day aboard Zanshin. I had noticed a constant drain of about 3A being used for the refrigerator and this seemed to be a constant use of power with a duty cycle of what seemed to be 100%. I remember reading that the duty cycle of a refrigerator should be at most half the time (in the tropics) so decided to delve into the matter and see if I could figure out what the problem was and perhaps manage to fix it myself without having to resort to getting professional help. The temperature in the fridge was at 10C, too warm but I was afraid to turn the thermostat down further because of the lengthy runtimes. Phase I was to get access to the compressors by removing a wide drawer underneath the oven and Phase II was to get out the vacuum cleaner and brush to clean up in there. Once it was reasonably clean I looked at the fridge compressor and was quite surprised that it wasn’t the ubiquitous Danfoss compressor but one from a Spanish company called Cubigel. The Cubigel “Smart Speed” controller and pins looked 100% identical to those of Danfoss so at I assumed that it was an OEM model, but later found out that it wasn’t, once I got access to the internet ashore.
Phase III was identifying the components and I spent a good 15 minutes trying to figure out where the return line from the evaporator plates was, it turns out that the return line is much smaller in diameter and was hidden behind the much bigger outgoing tubing, and both went into an insulated jacket right at the compressor. I turned off both the freezer and fridge compressors and let them cool down (or warm up) to the ambient temperature for a half hour before starting my measurements.
Phase IV was firing up the compressor and measuring the outgoing and the return line temperatures. The results confused me, not surprisingly since I made the mistaken assumption that the exit temperature was the cooling temperature. After a couple of minutes the outgoing temperature was between -0.5C and +0.5C and the return temperatures hovered around 40C (ambient temperature was around 29C) and I thought that I’d found the reason why the fridge wasn’t getting cold and why the compressor was running all the time. Then I measured the plate temperature inside the fridge and was surprised to read -11.9C before I realized that +0C liquid coming out of the compressor was being evaporated (hence the name “Evaporator Plate”) and thus cooling down further. So I was stymied and decided to head ashore to get connectivity to the internet and see if I could learn more.
Phase V was internet download time, where I found the website for Cubigel and downloaded the compressor specifications. Much to my surprise the wording in the documentation indicated that the Smart Speed controlling system adjusts the compressor speed downward to minimize the number of starts and stops, and one brochure mentioned duty cycles of 90%. This could explain the behaviour I’ve been seeing but when I looked at the jumper connector it seemed to indicate that the compressor was set to run at high speed. There is some software available where I can check to see if the compressor is set up for smart mode or uses the the jumper, but it requires a RJ-11 plug going to a serial port and I don’t have that cable aboard, so it has gone onto my list of items to purchase once I get back into town.
After finishing with the compressors much of the day was already gone, but I did get some work on the old LED systems done, watched a boat anchor so close to me that when we swung close there was less than 20 feet or so between us (they would swing behind me a bit) – despite the anchorage being relatively empty and Zanshin being anchored as the second furthest out boat (the furthest was the mega yacht Attessa IV, anchored very far away from the hoi polloi).
For dinner I went ashore and pondered the fine menus at some of the better restaurants, but in the end realized that fine dining wasn’t as much fun alone as it could be with company so opted for dinner at Sky’s the Limit LoLo close to the dinghy dock where I had a portion of ribs with salad. I lingered there and watched the crowds after dinner before returning aboard and finally finishing watching a movie on my PC before going to sleep.
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