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Old 15-03-2017, 13:12   #31
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Re: Refrigerator: AC vs. DC

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Originally Posted by sailorchic34 View Post
As someone who has had a 120V fridge for over 10 years. It's not that bad. My old fridge was a pig and used roughly 60 ah a day in 90+ degree heat. For a outlay of under $200 for the fridge and inverter, a cheap $40 msw inverter. It used about 2.5 ah on average running 10 minutes every hour.

The new 120V fridge uses about 26 watts an hour in 74 degree cabin temp and runs about 20 minutes every hour or so. Of course I got fancy and have a PSW inverter for the new fridge. Overall I save about 20ah a day, give or take over the old fridge. The biggy is of course the price. I spent $420 for my new fridge and inverter that uses about the same power or less then an equal 12V unit by norcold that costs $800 more and does not have a separate freezer compartment, which is an energy hog as it tends to over cool the fridge and cause partial thawing in the evap freezer bin.

A good 12V marine system should be a bit more efficient but it costs at least $1000-$1500 more. This has more to due with box insulation though then compressor efficiency.

As to the vertical door being an energy hog, that is again overstated. Yes some air will fall out of the door, but that may only amount to a pound or two of air a day (~10 cf, based on 5 openings) which would take roughly 100 btu's's (a day) to cool or an added 20 minutes run time, for less then 2 ah a day. It's a small loss. A large fridge would be more but for a 3-4 cf fridge its pretty much a non issue. With the money saved on refrigeration I can have a bottom job on the boat. Score....

BTW I am very happy with my 120V fridge (at anchor now)


Point taken,

3.1 cubic foot , 26 watts an hour is 640 watts a day or 52 amp hrs in 74 degrees . Am I right ?

Thats a lot , for a little fridge .

Now take that fridge home fridge and bounce it around for a week or two off shore at a 20 degree heel, to a place where it never falls below 90 degrees fahrenheit and call me in the morning.

It all depends what you are doing with your boat , offshore boat , offshore marine refrigeration system.

I have seen small fridges floating in the Caribbean sea

Regards John.
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Old 15-03-2017, 13:19   #32
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Re: Refrigerator: AC vs. DC

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One thing I'm thinking is with a Lagoon 440, you can fit a nearly insane amount of Solar and can accept less than the most efficient option. There reaches a point with anything that it takes twice the money to get a 10% improvement. I try to buy a couple of steps down from the best available in most anything as there is a point of diminishing returns.
If you have to have the best, your going to pay for it.
I have 1320W of solar. Output these days is 1500W for those who did not follow the other thread Solar output verse rating no comment please ! Back on topic, yes you are right I could choose a less expensive appliance, an A++ or A+ should will probably not consume more than my 12VDC fridge. So , that would be ok.
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Old 15-03-2017, 13:34   #33
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Re: Refrigerator: AC vs. DC

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ColdEh Marine, thank you for sharing your interest in the subject, but I really think you should gather some actual specification before making so many assumptions.

But most importantly I think you are missing an important point on the consumption matter. One fridge is rated by the EU label to be among the best, the other does not have the EU label (though it is Italian) and by spec consumes 3 times more.

Which one would you choose ? It seems to me the answer is pretty straightforward.

Brewgyver, you might search how the label works, it would certainly be interesting but I fear this thread will end up like the other one "solar panel ouput verse rating" Really, if you want that information to be useful then we also need to know the testing procedure of Vitrifrigo (or any other marine fridge maker) and I bet they don't publish it.

Yes you are right. I am assuming that they are testing a home fridge in a home environment. They really have no need to test a home fridge in a boat.

Again it all depends what you are doing with your boat , are you really a house boat with a mast or are you heading off shore doing extended cruising .

Regards John.
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Old 15-03-2017, 13:43   #34
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Re: Refrigerator: AC vs. DC

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3.1 cubic foot , 26 watts an hour is 640 watts a day or 52 amp hrs in 74 degrees . Am I right ?

Thats a lot , for a little fridge .

Regards John.
Ah but it's not per hour, more like every 1.33 to 1.5 hours. In 55-74 degree weather the fridge is using about 40-42 ah a day. So not too bad. I expect it will run more in summer as did the old one.

The old fridge worked for 10 years sometimes healed over 20-30 degrees. The compressor design for the 12V systems and 120v (220V) systems are basically the same type though the 12V systems tend toward smaller displacement then most 120V units. So the 120v compressors tolerate healing as well as the standard 12V units. No magic there. Energy saving has more to do with insulation then weather it's 12 or 120v. For the poor sailor, a nice 120V fridge works pretty well.

There are differences in motor power. My old fridge pulled 14 amps :-0, when running, but it only ran 10 minutes an hour in 90+ cabin heat. so not too bad. The new fridge draws 5.7 amps at 12.7v and runs about 20 minute run cycles and had a longer deadband. (freezer cycles from -5 degrees F to 25 degrees F). It pulls less amps probably because its a smaller displacement compressor. Though I suspect that much of the energy savings is due to separate compartments for fridge and freezer with no spillover. A nice design.
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Old 15-03-2017, 14:41   #35
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Re: Refrigerator: AC vs. DC

I would be willing to bet that the EU testing procedure for appliances to determine grading is very well documented with precise standards, what little I Remember of Germans and their TUV, I am sure that it is a very well standardized test
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Old 15-03-2017, 15:12   #36
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Re: Refrigerator: AC vs. DC

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Yes you are right. I am assuming that they are testing a home fridge in a home environment. They really have no need to test a home fridge in a boat.

Again it all depends what you are doing with your boat , are you really a house boat with a mast or are you heading off shore doing extended cruising .

Regards John.
I do not see how those two are exclusive ? I live full time on the boat, I was in the med last summer, now in the caribbean, going back to the med in a few weeks.

As others have reported here, there seems to be no particular problem with the 230&110VAC house appliances on monohulls. And since I was not successful at heeling my cat to 30 I guess it should be fine for me as well
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Old 15-03-2017, 15:20   #37
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Re: Refrigerator: AC vs. DC

Definitely 220 volt fridge delivered from a local or internet store. We did it and it was the best thing we did- twice as much volume as the 12volt version, far better efficiency, and worry free in the knowledge that if it fails it will only cost us EUR120 to replace.
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Old 15-03-2017, 18:53   #38
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Re: Refrigerator: AC vs. DC

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Definitely 220 volt fridge delivered from a local or internet store. We did it and it was the best thing we did- twice as much volume as the 12volt version, far better efficiency, and worry free in the knowledge that if it fails it will only cost us EUR120 to replace.
That's the kind of comment I was looking for ! thanks for sharing ! Be careful though, Australia I believe is using 230 VAC as in EU and not 220, and some people here are very sensitive about using the correct units & numbers
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Old 15-03-2017, 19:02   #39
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Re: Refrigerator: AC vs. DC

I am nearly all ac now never look back solar I use 24v panels they are cheap and I use them thru 24/240ac inverter then to appliances as in freezer bar fridge size with drawers (bettter ins.)and I use a timer to come on 4times in 24hrs. at min. therm. setting it works on my 4th boat now with this setup IT WORKS and it is inexpensive to run and replaceand I dont have to put up with 12v blackmailing techs.I also use 240 water heater (duetto).toaster..microwave.12v charger.and I am fully charged most days by 9am with 500w solar and 2 n70 truck style batteries ,after dark I only use my frig and 12v (charged during day) lots more of course but mostly keep as simple as possible good luk
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Old 15-03-2017, 20:39   #40
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Re: Refrigerator: AC vs. DC

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I am nearly all ac now never look back
So are you cooking with gas or using electric/induction?
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Old 15-03-2017, 21:08   #41
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Re: Refrigerator: AC vs. DC

Quote "I am assuming that they are testing a home fridge in a home environment. They really have no need to test a home fridge in a boat."

Where do I find the on boat testing procedure that companies like Nova Kool or Vitrifrigo have used when designing there fridges.

I would suspect that no testing or design has been done for 30 years because that is how old the technology and design is in most 12 volt DC marine refrigeration equipment on the market today.

Talk to any seller of 12 volt DC refrigeration and they will give you all sorts of reasons not to use domestic units on a boat.

Talk to most of the trawler guys, houseboaters or big power boaters, most run Domestic type equipment very successfully.

I currently have 2 x Vitrifrigo 130 lt refrigerators, 1 x Waeco 80 lt fridge, 1 x 100 lt Nova Kool freezer. and 1 x 65 lt Waeco portable fridge / freezer. All of which could be replaced by a single domestic 550 lt fridge/freezer. At the same cost as any one of the existing 5 units. It would use less power and not need to be defrosted every 4 weeks as is the current situation.

I just need to find a way to fit it on board.
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Old 16-03-2017, 04:52   #42
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Re: Refrigerator: AC vs. DC

Uh and ongoing discussion

I threw out my 230V Fridg Freezer with 230 l and built my own top loader box with 140 l fridge/freezer with 6 cm / 2 1/2 inches isolation. A new WAECO is serving.

Facts:
last three weeks the energy for the unit and interior lights was provided by the 2,8 sqm solar panels that charge between 6 and 18 A. Volage drop was from 13,8 to 12,8 V. Batteries were emptied 50%.

The f/f was only loaded 20% (which is not good) and after a half day of initial cooling the unit turned on 3 times an hour for about 5 minutes and used 1,6 Amps.

Resuming I do not see the A++++ arguments and the 230V/12V discussion.
My goal was to keep it simple.

Cost factor: The box and WAECO was about 1500€
And solar panels - Hmm I think they are a must have nowadays.
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Old 16-03-2017, 05:42   #43
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Re: Refrigerator: AC vs. DC

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Uh and ongoing discussion

I threw out my 230V Fridg Freezer with 230 l and built my own top loader box with 140 l fridge/freezer with 6 cm / 2 1/2 inches isolation. A new WAECO is serving.

Facts:
last three weeks the energy for the unit and interior lights was provided by the 2,8 sqm solar panels that charge between 6 and 18 A. Volage drop was from 13,8 to 12,8 V. Batteries were emptied 50%.

The f/f was only loaded 20% (which is not good) and after a half day of initial cooling the unit turned on 3 times an hour for about 5 minutes and used 1,6 Amps.

Resuming I do not see the A++++ arguments and the 230V/12V discussion.
My goal was to keep it simple.

Cost factor: The box and WAECO was about 1500
And solar panels - Hmm I think they are a must have nowadays.

Yes I agree, this thread is a non starter .

Call up your home fridge manufacturer and tell them you are using there product in a mobile application , sorry no warranty . Why ? They are not designed for it , I could go on and on why not , but I'm tired of

I warranty my system for 5 years in a mobile application.

I understand that every one want to save a buck , but get the right tool for the right job.

Again I say , depends on how you are using your boat . Crossing oceans or house boat with a mast.

As for efficiency . Take a close look at the photos I have posted , these were taken last night on my boat . The temperature inside the boat was 26.7 C , water temps this time of year are very cold , in the summer these numbers are 20% higher in power consumption.

You do the math.

Regards John.
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Old 16-03-2017, 06:29   #44
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Re: Refrigerator: AC vs. DC

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Yes I agree, this thread is a non starter .
Obviously a non starter for you because you are trying to sell something but fail to be convincing.

Anyway thanks everyone, I will get rid of my 12VDC marine fridges in favor of domestic 230VAC appliances as soon as I can. cheers.
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Old 17-03-2017, 11:55   #45
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Refrigerator: AC vs. DC

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Obviously a non starter for you because you are trying to sell something but fail to be convincing.

Anyway thanks everyone, I will get rid of my 12VDC marine fridges in favor of domestic 230VAC appliances as soon as I can. cheers.


Actually, you have to ask yourself just one question. Why do the marine magazines never do a comparison test between marine stand alone fridges and energy star A++++ fridges.
I seem to remember that these top line energy star fridges use around 140k watt hours per year and in case you are not convinced about their insulation properties, they keep the food frozen with the power off for 30 hrs.
Of course you can start discussing about what the test conditions were, and that's why the marine magazines should do the test.
Well... they're not going to or we would have had one by now and it would have made a very interesting read.

Any magazine brave enough??

Example....Household A+++ fridge freezer. Bosch Model KGE36DW40 uses 149kwh per year, keeps food for 35 hrs with the power off.
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