New refigeration unit

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August 31, 2015 at 10:53 #25827
Ronar M
Ronar M
Participant

Hi All
I am about to replace the refrigeration unit on Ronar M. For some time the old one has been struggling, cycling in and out almost all the time. Finally the plate in the cool box has stopped getting cool though the pump is still noisily whirring. I thought I might be able to refill the unit with refrigerant but apparently this is not possible/economic, so I have bought a new unit. I now have to take out the old unit and fit the new. I wonder if anyone has done this and can give me any tips which might save time and frustration.
Cheers, Trevor

September 3, 2015 at 22:20 #25828
Moderator
Moderator
Keymaster

Hi Trevor –

We had to replace our unit last year. I’m not sure if it was original or not, so unsure if it is like yours.

We had an Alder-Barbour compressor under the galley counter, with refrigeration lines running under the cooker and then to the CN-installed ice box. We removed the compressor and refrigeration unit from the ice box, and kept the ice box.

We replaced with a Isotherm ASU 3901, which has a holding plate and a really dumb “smart” controller. (We gave up on using the “smart” part and just manually control the setpoint based on our house battery state of charge.)

The isotherm has a Danfoss compressor, which is very good. It is much smaller than the original, so we relocated the compressor to under the ice box (right against the hull, not in the seat locker) in an area that was previously not used. To ensure good air cooling, we ran a rigid aluminium tube from the air grate we have aft of that seat locker and up to the air intake on the compressor. The air outlet blows out the air grate directly under the ice box. (Neither of these air outlets were used by our previous installation, so I suspect our 1980-installed Alder-Barbour unit was not original.)

Van had to remove the walls of the doored cabinet just forward of the icebox to install the new refrigeration lines. With much cursing, he got the interior of the cabinet apart piece by piece, without having to do anything to the nice front of the cabinet. And he got it all back together again so I cannot tell it was taken apart. While apart, he added as much insulation to the exterior of the ice box as space allowed. Many years earlier he had added 1″ foam insulation inside the ice box and covered it with formica to protect it, so we have considerably more insulation than the original installed ice box.

We did the refrigeration replacement in May 2014, so details are not so clear anymore, but the only lingering bad memories I have is how the unit did not have sufficient coolant charge after we completed the installation (losing no coolant in the process), but fortunately we have a friend who repairs refrigeration so was able to fully charge the unit so the entire holding plate would freeze. We also had to install a small thermostat-controlled fan internal to the ice box (between our ‘freezer” area and the “refrigerator” area within the ice box) to circulate the air to get more even temperature distribution, but now it works well (provided we remember to manually control the holding plate setpoint, which has now become habit.) The thermostat for the internal fan has its own thermocouple to control the temperature within the refrigeration section, while the Isotherm control has its own thermocouple to control the holding plate temperature.

Hope something in that long note is useful.

Marilyn and Van

October 3, 2015 at 11:58 #25836
Voltair
Voltair
Participant

Voltair’s fridge had been limping along for some time but in 2014, shortly after leaving the Spanish mainland for Ibiza, it turned its toes up for good. We bought a “sealed package” from a supplier on the mainland who arranged to ship it to Ibiza for us, and we did a self installation within one day, putting the new compressor/condenser under the fridge box just as it had been previously. The new condenser seems to work a lot better than before, and I was able to do away with the computer fan blowing air at the condenser (thus saving an amp), but the new compressor uses slightly more juice than the old one did (5-6 amps), though it is a little less demanding on startup than the old one was. We rate it a success, since this Mediterranean cruising is new to us, and we have mainly had cool if not cold beer ever since, even with the cabin at 35C it was still working OK. Further improvement could be made by changing the insulation around the original cabinet, which is patchy and poor, but difficult to get at, especially behind the cabinet. It has NOT solved the problem of providing 5A x 18hr = 90Ah energy per day (75% duty cycle) with most of this being at night, without flattening even new batteries of the highest calibre. Can send you more detail if you need it. Total cost was about €500 from memory.

October 4, 2015 at 16:15 #25841
Ronar M
Ronar M
Participant

Hi Both,

Thanks for your detailed replies, which were very useful. I have now fitted the new fridge unit which has proved very efficient and so much quieter than the old one. The one I fitted was made by Waeco and has a Danfoss compressor unit. I too think it is a bit more ‘thirsty’ than the old one. The only problem I had was that the new unit stands on a square base plate whereas the old one was narrower and rectangular. However, I was able to cut away part of the support for the old unit to make way for the wider square base plate. The power cable and the tubes to the evaporator plate (one inside the other) fitted easily down the side of the cool box.
Cheers, Trevor

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