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Old 29-09-2015, 09:37   #31
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re: Why no Residential Fridges?

OLDRAGBAGGER

I is the small one purchased 12 years ago. Still runs fine. 2.5 amp/hr.
About 40 amps a day in Florida.
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Old 29-09-2015, 09:51   #32
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re: Why no Residential Fridges?

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Originally Posted by Scaramanga F25 View Post
Only if it has a swing motor compressor.
This Edge Star unit seems to take much more amp/hrs: 5.4 amps @12 volts.
You know, that's not what I'm coming up with, seems the main advantage of the swing compressor is low start up loads, but running current draw is very similar.
I have been wondering just how much sense it might make to buy a big fridge / freezer, cut out the built in ice box and drop it in, replacing the built in ice box myself, for those of us that just cannot fit a home fridge.
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Old 29-09-2015, 09:59   #33
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re: Why no Residential Fridges?

As I recall there is an issue with the AC neutral and AC ground being bonded on residential refrigerators and that can cause a problem with the proper handling of that on a boat. Any one with specifics, please chime in. I am sure there are boaters out there who have not bothered with this, or have never heard of it, and, have never had a problem. I believe it is supposed to be a safety issue. It also has to do with inverters which should have a relay to disconnect the inverter's internal "bonding" of the neutral/ground when on shorepower.
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Old 29-09-2015, 10:00   #34
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re: Why no Residential Fridges?

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Hey all,

I'm a total newbie, starting the research for living aboard a few years from now.

My family's been living in an RV for the past year, and so I have become well-acquainted with the systems we have. I am now trying to translate my understanding into things more appropriate for at sea.

The first thing I can't figure out is, why are there no residential fridges in boats? RVs basically moved to these a couple years ago, I suppose in part because they are so efficient now and in part because the Norcolds and Dometics of the world were so notoriously sucky. (And because with induction and microwave convection cooking, one can get rid of propane entirely and make things a lot simpler.)

So... is it just a space issue? Could it be something with orientation/motion? Or maybe rust and corrosion?

Thanks for clueing me. And be gentle, first post.
Maybe you need to define live aboard. Berthed all the time, anchored or sailing?
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Old 29-09-2015, 10:03   #35
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re: Why no Residential Fridges?

We have done many refrigeration systems on cats over the years with solar support. Cat's have the deck real-estate to support significant solar arrays. Unfortunately weight is a big liability on cats, your concept would require significant more battery and array weight to buffer the many hours of non-productive panels. A small domestic refrig/freezer is poorly insulated, air cooled (least efficient) and dumps the dry cold air out and reloads with warm moist air with each door opening. The smaller of these style fridges require a minimum of 130 watts, if you assume a normal 80% duty cycle, you are looking at about 2470 watt hours, plus the efficiency loss of the inverter conversion. At my latitude in the Keys, with efficient panels, average solar charging period is 5.5 hours, which equates to 550 watts of solar (30 sq. ft) dedicated to supporting your small fridge. Secondly you need 197 amp hours to support this fridge, that's the usable capacity of approx. two 8D batteries. This is a lot of weight and infrastructure to support an enameled steel shelled refrigerator that assumes a low humidity home. So much more cost effective and far less infrastructure required for a good marine refrigeration system that consumes a fraction of the power and many perform for decades.
Bob
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Old 29-09-2015, 10:06   #36
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re: Why no Residential Fridges?

Dorm sized fridge running off a small inverter off your battery bank. Just as efficient as a common boat fridge like my Adler Barbour. According to long time liveaboard and electrical engineer Sailorchic34.
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Old 29-09-2015, 10:25   #37
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re: Why no Residential Fridges?

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Originally Posted by onestepcsy37 View Post
Dorm sized fridge running off a small inverter off your battery bank. Just as efficient as a common boat fridge like my Adler Barbour. According to long time liveaboard and electrical engineer Sailorchic34.
Depends on the dorm fridge. I was considering using one temporarily while having fridge problems. I put a meter on a cheap no name I already had ashore...and holy amps hours! It drew a several times more juice than the similar sized 12V one aboard with a Danfoss compressor.
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Old 29-09-2015, 10:35   #38
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re: Why no Residential Fridges?

Some residential refrigerators have become surprisingly efficient. They are not the cheap ones however. Even accounting for Inverter inefficiency, per CU ft some of the newest fridges may be more energy efficient then the DC ones out there. Check this link
ENERGY STAR Certified Residential Refrigerators | EPA ENERGY STAR

Some of these draw as little as 1/2 a KWH a day I believe this would be lower then a similar size conventional DC fridge by a ways. (super insulated water cooled custom jobs may do better). Using the Engle as an example if you draw 40AH a day you would be right about even with an AC fridge of twice the capacity (before inverter and wiring efficiency is counted). of course you would need the space and proper venting to make it work correctly.
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Old 29-09-2015, 10:39   #39
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re: Why no Residential Fridges?

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Looks like a feasible idea. I am assuming you need to exhaust the condenser heat. Do they give any info on duty cycle closed and loaded with cold beer or frozen food? one for each and top loading makes sense. At that price it is about a throw away if it takes a dump.
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Old 29-09-2015, 10:42   #40
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re: Why no Residential Fridges?

The CSY37 I believe is being discussed was built by Vanost with a well insulated box that could be supported with a keel cooled (no strainers, pump or open thru-hulls) Frigoboat unit with freezer section for well under 75 Ahrs per day. Adler Barber units do not set and standards for efficiency, just price. Over the past 30 years we've completed more refrigeration systems for OEM's and cruisers than most, many of our employees being live aboard cruisers, me included. It's almost a cliche; buying cheap on a refrigeration system will drive the majority of your energy management process and investment onboard. Better to look at Watt's per BTU on your condenser, water cool for 25% in tropic run time and use no less than 4" of 2 lb density insulation (cheap), with barrier coat and foil UV block on hull side. This in the end will save you thousands in unneeded infrastructure.
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Old 29-09-2015, 11:05   #41
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re: Why no Residential Fridges?

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I know you can get the Edge star and others for 1/2 what an Engel costs, but read all the user's posts first. 50 per cent say," it was fine after I re-wired it", or"it worked great for the first four months". I haven't seen one bad review for Engel. Nor have I talked to an Engel owner that had anything but praise for them.
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Old 29-09-2015, 11:41   #42
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Re: Why no Residential Fridges?

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Your right, but I think they are talking about a large Cat, I was going to bring up how it sucks every time you open the door and everything spills out, RV fridges have wire rails to prevent this, but then realized they are talking about a Cat, again.
Gotta think that seeing as how it seems you can put a rather large Solar farm on a big Cat, that a house fridge may well be a viable option? Not in my 38' mono, but why not on a big Cat?
My current plan is to buy a 45-47' cat with chest type fridge and freezer. If the insulation hasn't already been upgraded, I'll do that, convert both units to fridge and install a chest type 8-10 cuft 120v freezer (unless I can find a really efficient 12v version that size) or perhaps 2 x 5 cuft units and simply power up the 2nd one only if the first one is full. That's in addition to the solar farm.
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Old 29-09-2015, 11:43   #43
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Re: Why no Residential Fridges?

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Historically 12V refrigeration has been much more efficient. Brand name residential fridges are getting more efficient. I tested a small no name 120V fridge a while back and it was wildly inefficient, but have a friend who lives off-grid who recently installed and Samsung 120V fridge and has been pleased with its performance (sorry, dont have numbers).
Marine fridges usually are water cooled rather than air cooled. Water cooled is much more efficient (theoretically) than air cooled due to the much greater thermal density of water. Think about it...if you burn your hand, will you blow on it, or run it under water? Water pumps can be small and silent, while air pumps (fans) are usually noisy and inefficient. Also, water comes and goes over the side via through hulls...where do you blast the hot air on a boat?

If you read the instructions on most new (land) fridges, you must let it "sit" for at least 1 hour after moving, so that the refrigerant can settle. Sailing will certainly unsettle the refrigerant.

And finally, a humid salt air environment will destroy anything not built specifically for a boat. I lost some great flashlights and other handheld devices this way. The salt air gets into everything. Low grade steel, common on household appliances, doesn't stand a chance.
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Old 29-09-2015, 11:49   #44
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Re: Why no Residential Fridges?

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Depends on the dorm fridge. I was considering using one temporarily while having fridge problems. I put a meter on a cheap no name I already had ashore...and holy amps hours! It drew a several times more juice than the similar sized 12V one aboard with a Danfoss compressor.
Yes a 120V fridge will pull a ton of 12v amps.... when it runs. But I've found that the duty cycle of a 120V dorm fridge is roughly 10 to 12 percent. In other words, when it runs, it's pulling 15 amps, but because it has a short duty cycle, the average hour amp load is ~2.5 amp/hr. Which is actually pretty darn good. So it's not just peak amp load, but amps actually used in one hour.

I am seriously considering upgrading to a fridge with separate fridge compartment that draw's 100 watts running. My 8 year old fridge is using 175+ watts (though only for roughly 10 minutes an hour). I'm hoping to get that by christmas and will report on how it does.

That whole thing about sailing and healing angle with a dorm fridge, I've never had a problem with. The compressor design of the 120V fridge and 12V fridges (other then engel) are for all intents the same.
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Old 29-09-2015, 11:54   #45
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Re: Why no Residential Fridges?

While I don't think it's a good solution, Bali Cats offer household style fridge/freezers >> Bali Catamarans.

They are likely air cooled, which means less efficiency, and the power demands must be huge. Likely mandatory to have a generator running much of the time.

A better solution IMHO is built in, highly insulated cabinets running Frigoboat keel cooler systems that are water cooled without the throughhulls and water circulation power costs. We have a 100 liter and 200 liter fridge/freezer, either of which can be a fridge or a freezer just depending on how you set the thermostat. We are self sustaining on solars alone, along with all other electric loads (no generator) except when we sail for several over nights or more when we'll need to motor some to recharge batts. When we depart on a winter cruise we make the 200 l the freezer and carry all of our meats (except expected catches of fish) and more for an entire 7 month cruise in the tropics. Half way through the cruise, when the frozen stuff will fit into the 100 l cabinet, we swap the functions and give the batts a rest...

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