Since the weather here in Paradise hasn’t been particularly Paradise-like, it seemed like the right opportunity to get to work on a few maintenance projects. Since we plan to head to the Bahamas in the next week or so, the Grunert (our holding plate storage freezer) is up on the list. I haven’t been particularly satisfied with how it’s operated from the beginning, and was following some comments on the Selene owner’s forum about other owners’ experiences with theirs. I concluded that ours just wasn’t working the way it is supposed to operate, plus the refrigerant lines inside the cabinet adjacent to the freezer enclosure were frosting and melting off, creating a mess in the cabinet.
I called Dometic Customer Service, the manufacturer, and got some setup and charging specs, and related the problems I was having. A productive call, I now had some good information and could come troubleshoot the system. After some
investigation, I determined that there were a number of things that were wrong, all fixable. The unit was overcharged, the thermal expansion valve was set incorrectly, the eutectic plate (holding plate) was incorrectly mounted tight to the side wall and bottom of the freezer cabinet, reducing the capacity by 40%. I remounted the holding plate, adding spacers to keep the plate the spec’d 5/8″ away from the wall and floor of the enclosure, allowing circulation around the plate. While the plate was loose, I removed all the old insulation from the refrigerant linesets, and installed new armaflex. A full 1″ thickness on the expansion valve and section of tubing into the plate, and 1/2″ on the suction line leaving the plate. I also cleaned and re-attached the bulb for the TXV, adding some thermal paste at the contact point. Also cut away the cabinet from the refrigerant tubing, allowing a full one inch space for insulation. I filled some voids with canned foam, and put everything back together.
The results of the day and a half effort is a fairly dramatic improvement in operation. The freezer temperature now drops to about 10F empty, where before it would only go to about 22F, loaded. It now only takes about an hour of run time where before it would run for over two hours to net the same results. After running this evening, we loaded it with things removed from the freezer and will see what the results are overnight. One thing learned from the Selene forum is that the unit won’t operate as a freezer, per se. It is a holding plate system, and is really not intended to freeze things, just to keep frozen things that are already frozen. Our Tundra refrigerator/freezer does a pretty good job of freezing meats we get from the grocery store, so they go there first, then into the Grunert for storage.
The second maintenance project involved the 12 volt electrical system, specifically the part of the system at the main panel in the pilothouse. The refrigerator had been cycling and was dropping temperature while running on battery power, but ran without problems on shore or generator power. A call to Tundra’s service line, pointed me toward a voltage problem, and some troubleshooting showed a voltage drop in the power supply of enough significance to cause the power supply to cycle on low voltage. Further investigation showed several points where voltage drops of a tenth to a half volt were present, Not a lot, but on a 12 volt system, the cumulative effect can create havoc. One item that was suspect was the grounding buss used in the main distribution panel.
The OEM busses are brass with brass screws. I had replaced one of them in the flybridge panel and realized significant reduction in voltage drops, so I picked a buss up in Key West at the great marine hardware there. It’s a Blue Seas, and their buss bars are all tin plated copper. They claim 30% better conductivity, and the improvement is significant. With that, plus removing, cleaning, and re-attaching all the other 12 volt main feeders and connections, the voltage drop at the termination of the refrigerator is negligible now, vs. about a half volt drop prior to the re-work. I had noticed some heating of those 12 volt mains before, it will be interesting to see if that is eliminated now.
Whew, pretty exciting stuff, not?!! And you thougt life in Paradise was just lying on the beach drinking margaritas! (I don’t really like margaritas 😎 Well, that’s a slice of life here in Paradise, in excruciating detail.
Coming up, strainer service, water pump rebuild. The maintenance never ends!
Out.
Mother on 07 Mar 2009 at 8:27 AM #
While you were doing all that, was Barbara drinking marguaritas , sitting watching you work?
Mother