Why no Residential Fridges?

[travellerw]

Originally Posted by SV THIRD DAY

I shouldn't do it...but I will...I'll expose my evil dark side as an off the grid, doomsday prepper show vendor.....

We can barely fill orders for these fast enough, basically here's what we do.Take an off the shelf 120v AC refrigerator, rip out the 120V AC compressor and then install a 12v DC compressor like a Danfoss BD35/50 or Cubigel.

12v Solar Refrigerators and Freezers for Off the Grid Living

Rich...Rich...Rich....you are crazy. Why would I pay $995 for one of these?

Hmmm your fridges are still $500 cheaper than comparable 12V "cruising" fridges at Defender. Even cheaper if I DIY.. Hhhmmmm

Very comparable model here!
Isotherm Cruise EL 130 Elegance Refrigerator / Freezer

[Scot McPherson]

Since I am building my own boat, I planned on building my own chest style freezer and frig into the woodwork. Gives me the opportunity to ensure the quality of insulation, and where and how the cooling system is designed.

Here is a link to how to convert a chest freezer into a super-efficient fridge.

http://www.mnn.com/green-tech/gadget...most-no-energy



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[bobw100ton]

The propane factor aside, all ammonia based absorption refrigeration units we have seen use steel condenser tubing painted with black enamel. The advantage of "no moving parts" is offset by the high probability of a corrosion failure with a sudden release of a full charge of ammonia into a boat because it can't vent a breach overboard fast enough. In the highly corrosive marine tropics they've stopped using them on charter cats.

[Cadence]

Originally Posted by Scot McPherson

Since I am building my own boat, I planned on building my own chest style freezer and frig into the woodwork. Gives me the opportunity to ensure the quality of insulation, and where and how the cooling system is designed.

Here is a link to how to convert a chest freezer into a super-efficient fridge.

DIY fridge uses almost no energy | MNN - Mother Nature Network



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The PFD sounded like Gullable's Travels.

[TeddyDiver]

Originally Posted by bobw100ton

A 115 VAC air-cooled hermetically sealed home refrigerator compressor built into a enamel painted steel front load refrigerator is a far cry from the efficiency of a hermetically sealed modulated DC to 24vac compressor (such as the most common German made Danfoss compressor) when water cooled

Hmm.. perhaps there's something very different on that side of the pond becouse our 240V home fridgess are so much better that :P
But maybe we have here German made Danfoss compressors in home fridges too?

[onestepcsy37]

Originally Posted by bobw100ton

Efficiency is not cheap because the economy of scale doesn't work in favor of the cruising sailor.

Economy of scale goes in two directions. We have "enough" fridge/freezer for our cruising needs and run it off a 130 watt solar panel. Cheap and simple. We do have more than the typical insulation than most factory boats have. The system is an Adler Barbour CU200, air cooled only, in Florida/Bahamas.

And I have never ever been connected to shore power, not even in a marina. The boat is all 12 volt.

[valhalla360]

Originally Posted by bobw100ton

The propane factor aside, all ammonia based absorption refrigeration units we have seen use steel condenser tubing painted with black enamel. The advantage of "no moving parts" is offset by the high probability of a corrosion failure with a sudden release of a full charge of ammonia into a boat because it can't vent a breach overboard fast enough. In the highly corrosive marine tropics they've stopped using them on charter cats.

Ours is 20yrs old. Other than a few spots of surface rust on the condenser coils, works fine. The one in my Dad's trailer is closing in on 40yrs old. It has had extensive use in Michigan in the winter, so plenty of salt exposure.

Salt air isn't good for compressor motors and condensors either and a sudden release of freon (or the new equivilent) will leave the unit equally dead.

[SV THIRD DAY]

Originally Posted by TeddyDiver

But maybe we have here German made Danfoss compressors in home fridges too? [IMG]file:///C:\Users\CRUISE~1\AppData\Local\Temp\msohtmlclip1\ 01\clip_image001.gif[/IMG]

Ahhhh....there are no more German made Danfoss compressors, hasn't been for years. They were bought out by a Chinese company and moved their compressor production to China.
Our first pallet of made in China Danfoss compressors had close to a 30% failure rate right out of the Box...which is when we switched to Cubigel made in Spain. I'm sure they got it all fixed up now...but maybe Donand Trump can fix it? ha ha ha

[nebster]

Originally Posted by bobw100ton

A 115 VAC air-cooled hermetically sealed home refrigerator compressor built into a enamel painted steel front load refrigerator is a far cry from the efficiency of a hermetically sealed modulated DC to 24vac compressor (such as the most common German made Danfoss compressor) when water cooled.

What's a "far cry"? Do you have any data we can look at? I'd like to know kWh per day for a given refrigerated volume, since we certainly know what this is for modern high efficiency residential refrigerators.

[travellerw]

Originally Posted by nebster

What's a "far cry"? Do you have any data we can look at? I'd like to know kWh per day for a given refrigerated volume, since we certainly know what this is for modern high efficiency residential refrigerators.

If you compare the fridge that Rich sells and the one I posted on Defender, they draw almost the same. Of course this is just literature, but I tend to trust Rich as he seems to underspec his gear. Ask anyone who owns one of his water makers.

[nebster]

Originally Posted by travellerw

If you compare the fridge that Rich sells and the one I posted on Defender, they draw almost the same. Of course this is just literature, but I tend to trust Rich as he seems to underspec his gear. Ask anyone who owns one of his water makers.

I'm not sure if the one you posted is the same as the one the person above is referring to, but let's run with it. From the site, "418W / 24 hours", which isn't a measure of energy, but let's assume they meant 418Wh per 24 hours (17W average duty). And we have 4.6 cuft of space, so we're spending 90Wh per day per cubic foot.

Top-rated (by Energy Star) models are in the 600kWh/year range, or 1650Wh/day for about 25cuft. That's 65Wh per day per cubic foot. Not sure if that is considered a "far cry" or if it is considered to be one in the right direction.

[sailorchic34]

Originally Posted by SV THIRD DAY

I shouldn't do it...but I will...I'll expose my evil dark side as an off the grid, doomsday prepper show vendor.....

We can barely fill orders for these fast enough, basically here's what we do.Take an off the shelf 120v AC refrigerator, rip out the 120V AC compressor and then install a 12v DC compressor like a Danfoss BD35/50 or Cubigel.

Hum from an engineering standpoint, a 4 ish CF box fridge will use about the same amount of btu's/watts per hour to cool the insides, whether its 120V, 220V or 12V. That heat loss will be the same through a give box with the type of insulation.

So giving that both the 120V and 12V compressors are using 134A, and have similar motor and compressor design and efficiencies (close enough for engineering and not counting engel's swing compresson, which is cool) , I would expect the hourly watt load to be near about the same, say within 20% or so.

No question you'll get a heart attack looking at the running amp draw on a small 120V compressor, But I find that the hourly duty cycle is pretty low, they pull less then 3 amps per hour on my 3.5 cf fridge and that was in the delta with 90 degree cabin temperatures. It was really about 2.5 amps per hour, though more in 100 degree cabin temps.

Yes a small 120V fridge pulls 15 amps (at 12.8 ish volts), when it runs. But mine only runs 2.5 minutes +/- every 15 minutes or about 10 minutes per hour. It ain't that bad. Mind you my little $200 system (fridge plus inverter) has been working for 8 years now and yes I'm at anchor. Though OK I spent a few years with the boat mostly (80% of the time) at the dock. Would I like a 12V system.. sure. But not for $1000.

[Matt Johnson]

Originally Posted by travellerw

Hmmm your fridges are still $500 cheaper than comparable 12V "cruising" fridges at Defender. Even cheaper if I DIY.. Hhhmmmm

Very comparable model here!
Isotherm Cruise EL 130 Elegance Refrigerator / Freezer

Sure marine is under $800 for the Vitrifrigo 4.2 cu ft with a Danfoss compressor. The best quality? No. But it is cheap.

Vitrifrigo C115IBD3-F (Old # C115I) 4.2 CU FT DC Only Marine Refrigerator with Flush Flange

We just received a BD35 compressor ($435) and the 30" x 10" evaporator ($135) from them for $610 shipped to Florida. It's very similar to the set-up we cruised with for three years without issue. I'm sure the new one will be similar.

Matt

[jeepbluetj]

So there's a range of refrigeration options.

Purpose built marine stuff. (Keel, water, or air cooled, holding plate or evaporator)
'Portable' units like engels.
Residential units.
Even propane units. (Google images of RV fridge fire for fun. I hated my propane fridge)

What's best? Who knows. Depends on your use, $$ budget, and power budget. They all seem to work. I'm pretty sure one of Rich's coolblue units is way better than a dorm fridge WRT electrical use (24AH/day!!!), longevity, repair ease, overall slickness of installation, etc.. But a dorm fridge is pretty dang cheap.

[Cadence]

Originally Posted by sailorchic34

Hum from an engineering standpoint, a 4 ish CF box fridge will use about the same amount of btu's/watts per hour to cool the insides, whether its 120V, 220V or 12V. That heat loss will be the same through a give box with the type of insulation.

So giving that both the 120V and 12V compressors are using 134A, and have similar motor and compressor design and efficiencies (close enough for engineering and not counting engel's swing compresson, which is cool) , I would expect the hourly watt load to be near about the same, say within 20% or so.

No question you'll get a heart attack looking at the running amp draw on a small 120V compressor, But I find that the hourly duty cycle is pretty low, they pull less then 3 amps per hour on my 3.5 cf fridge and that was in the delta with 90 degree cabin temperatures. It was really about 2.5 amps per hour, though more in 100 degree cabin temps.

Yes a small 120V fridge pulls 15 amps (at 12.8 ish volts), when it runs. But mine only runs 2.5 minutes +/- every 15 minutes or about 10 minutes per hour. It ain't that bad. Mind you my little $200 system (fridge plus inverter) has been working for 8 years now and yes I'm at anchor. Though OK I spent a few years with the boat mostly (80% of the time) at the dock. Would I like a 12V system.. sure. But not for $1000.

Obviously you missed replacing the 110V compressor and sweating in a 12V. Dah! We can go into business and make millions.