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Old 08-14-2012, 04:22 AM   #1
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Fridge differences

Aloha all, my DC refrigerator is in need of replacement and I was wanting some input on different systems. The DC unit stayed at a constant cool and never really got cold. It seems the AC/DC units I look at have DC compressors with an AC option. Any one use these? Any one use a basic 110 volt fridge. Mahalo for your input.
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Old 08-14-2012, 05:57 AM   #2
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The question is what was it made for?

Second question is what do you want to save.

A house fridge is built for max internal volume , so thin insulation and a heater required to dry the insulation.

Huge power hog , hardly a problem at the power pole.Or motoring with a small cheap inverter

The RV and other vehicle fridges will be more robust and usually be better suited to a boat.Door locks and shelves that try not to spill .

The "off grid" stuff like a Sun frost has wonderful insulation and a good AC or DC internals. But none of the RV/boat features like door locks.

If you want to go on the hook, the price will be either a few hundred pounds of batts per day , lots of noisemaker and reduced batt life or a different energy saving method.

A big eutetic plate (brine tank) works in a well insulated box , for a quiet night or even two.

For me , propane , with 30 days of silence works the best .

IN RV stuff the ones that vent to the cabin seem to be easiest to build in, and not overheat.
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Old 08-14-2012, 12:47 PM   #3
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I have a standard 110v household fridge that was installed by the previous owner, including a 2500 watt inverter.
So far it has worked out fine. Boat originally had 2 6v batteries as the inverter bank. That worked for weekending.
I changed to 4 6 v batteries ad so far we have been cruising for 8 weeks and it is working out fine.
When we are anchored for one night, battery power is enough, we don't run the genny. 2 nights probably not either unless the previous day's run was very short (less than 3 hours).
So far on this cruise we have only logged about 8 genny hours.
Hope this helps.
Jay
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Old 08-14-2012, 04:54 PM   #4
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I replaced mine with a vitrifrigo unit from Defender.Max draw is 2.8amps and it fits under the counter like the original propane unit. The admiral said to get rid of everything that used propane including the stove and oven. They have been replaced with electric. My grill on the aft deck uses the disposable canisters.
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Old 08-14-2012, 05:43 PM   #5
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We have three DC units on board, two fridges and a freezer. All use Danfoss compressors. The most efficient is the Isotherm 130 litre fridge - no icebox. It's an underbench fully self-contained unit and averages about 10ah per day - at 24V. At night it runs in fan-only mode virtually all night. The smaller one -a 70 litre drinks fridge - is not as efficient. Could be because it gets opened more often!
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Old 08-14-2012, 05:53 PM   #6
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My boat has a Nova Kool AC/DC refrigerator and it works fine. Set it too cold and it will easily freeze the contents of the refrigerator. It's designed for the limited power available on a cruising boat and it's pretty efficient.

Isotherm is the brand of AC/DC refregerator on my previous boat and it worked well also. Isotherm and Nova Kool have good products and good reputations.

If you're installing it in a boat that won't have a genset running 24/7, I would recommend a marine AC/DC refrigerator for efficiency and longevity.
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Old 08-14-2012, 05:59 PM   #7
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I have an apartment-sized household fridge (Korean eWave) that I think is around 11-12cf. Installed it maybe 8 years ago to replace a same-size older unit that consumed a lot more power. I think this one is around 1.2a 120VAC (from memory). I added a muffin fan in the cabinetry in the back to pull air from underneath and some insulation panels on the side. I think the cost was around $150? I have a 3KW inverter with 1200AH of large AGMs that's always on, so for me it was a cost-effective solution.
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Old 08-15-2012, 02:24 AM   #8
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Fridge

Mahalo for all the responses, they were quite helpful.
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Old 08-15-2012, 06:01 AM   #9
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One concept that is found in some RV or boat fridges is a voltage sensor , and a different thermostat.

When DC power is available and the voltage goes to charge level (near 14V) the unit will begin to operate .

The thermostat allows the box to operate to a lower temp, (hopefully not low enough to freeze the vegis ).

This could be a help for some cruising styles.
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Old 08-15-2012, 08:19 PM   #10
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Yep, Isotherm calls it ASU. Especially good for yachts when engine operation is intermittent.
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