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Old 05-10-2018, 05:19 AM   #41
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"The efficiency best, as I understand it is Frost King. Expensive though"

You might compare it with Sunfrost , built for off grid operation.

Sun Frost: Energy Efficient Refrigerators, Freezers, and Sustainable ...

Energy Efficient Refrigerators, Freezers, and Sustainable Living Products - Sun Frost


Sun Frost: worlds most energy efficient refrigerators and sustainable living products. Including composters, solar vaccine refrigerators and composting toilets.

Most of the hassle of refrigeration power use comes from the desire to use an off the shelf unit.

In past times the refrigeration was built into the vessel , so massive 4-6 inch insulation helped and large eutetic engine driven systems could capture many HP of energy in a short period of time.

For a dedicated cruiser that prefers silence to noisemakers , it is still an option.
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Old 05-10-2018, 08:25 AM   #42
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Ya got me FF, I misspoke..... I meant Sun Frost. A brand you pointed out to me sometime back.
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Old 05-10-2018, 08:33 AM   #43
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On boats with lots of power available on demand

it is an entirely different conversation compared to those camping on the hook for months at a time without burning any dino juice.

The latter group is willing to sacrifice space to get down below 40AH per day at 12V.

The former can afford to think in kWH and want all the comforts of home.

It is true that the modern super-efficient 240AC units available in the non-US more-developed world can get **almost** as efficient even with inverter losses as the 12V Danfoss type portable units or sailboat-style custom jobs.

But the latter have the efficiency advantage of a custom box which can be super-insulated, makes a huge difference. But at a higher cost.
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Old 05-11-2018, 02:03 AM   #44
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It is true that the modern super-efficient 240AC units available in the non-US more-developed world can get **almost** as efficient even with inverter losses as the 12V Danfoss type portable units or sailboat-style custom jobs.

But the latter have the efficiency advantage of a custom box which can be super-insulated, makes a huge difference. But at a higher cost.
There was another thread, either on this or Cruisersforum, and we contributed numbers for actual energy usage. I recall that the high efficiency household units (plus inverter) were more efficient than the old-technology Danfoss types.

When I measured from my other villa, the refer (12-14 cf roughly) was consuming 500 watts daily. Digital inverter technology. So that works out to about 42 amp-hrs per day at 12 vDC. But the temperatures here are probably more extreme than in a boat since we don't run the aircon when away from home - the kitchen gets really hot during summer where outside temps are 125-130 degrees.

Cost wise a custom built marine unit is generally more expensive as well, as you mentioned above.

Of course many boats cannot accommodate a household unit.
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Old 05-11-2018, 05:14 AM   #45
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"Of course many boats cannot accommodate a household unit."

However the RV or Amish style ( Servelle) propane fridges solve all the problems.

A single 20# tank will keep a large home sized reefer cold for a month , in silence.

Even cokling with the reefer supply does not seem to matter much to gas consumption.

A safe well engineered propane system can be done .

On out launch the unit is simply mounted in the cockpit, which is self draining.

Its a lot less of a PIA to need to go outside to get the food,. drink, ice and ice cream than have a noisemaker , batterys by the dozen , and an expensive complex system to maintain.

Our goal is always to cruise with the least hassle . the reefer /cooking hassle is easily solved with propane.
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Old 05-11-2018, 06:18 AM   #46
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RV sized Propane refrigerator freezers will burn a 20# tank of propane in 10 days in hot humid weather. Engineers from Dometic said to expect 1.4 to 2.1 pounds per day depending on temp/humidity.
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Old 05-11-2018, 07:39 AM   #47
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Here is a good discussion on the merits of propane fridges vs electric.

Off Grid Refrigeration: Solar Electric Vs Propane | Sun Frost Blog

I recognize that there are problems with some of the data on Sunfrost's web site, but the principal is accurate.
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Old 05-11-2018, 08:02 AM   #48
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The scariest problem I saw on their Website were the prices....Holy Cow!
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Old 05-11-2018, 08:07 AM   #49
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Quote:
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RV sized Propane refrigerator freezers will burn a 20# tank of propane in 10 days in hot humid weather. Engineers from Dometic said to expect 1.4 to 2.1 pounds per day depending on temp/humidity.
And around here, your 20# tank will be "filled" to only around 15#s.
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Old 05-11-2018, 09:22 AM   #50
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Yes it is "possible" for propane to be safely used inside the living space on boats.

Some men are willing to live and work for decades on nuclear subs too.

Not me.

When an efficient $600 Engel and $400 worth of solar will do the trick.
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Old 05-11-2018, 11:40 AM   #51
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I like the propane refer idea, but consuming that much gas only is practical if you live a “steady” life. For those cruising various countries then there will be difficulties with refilling.

I’m impressed by the guys here with large solar arrays who can provide almost 100% of their electric needs cleanly (not including aircon of course).
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Old 05-11-2018, 12:54 PM   #52
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"RV sized Propane refrigerator freezers will burn a 20# tank of propane in 10 days in hot humid weather."

Ours has been in use for a decade , and worst case is 18 days in Fl sun .

It sits on the aft deck in a ply box with zero added insulation.

A couple of inches of insulation , or a sun shade would help matters a lot.

The newest RV units can be double sized from the older units .

Servelle sez,

The Dometic Servel RGE400 Refrigerator serves its purpose in longevity. Even in hot climates, this Dometic Servel RGE400 will freeze popsicles and pass the 'ice cream test'. This finely crafted appliances operate on either propane, at the rate of about 1.8 Gals per week (7.7 pounds), or standard backup power of 120 volt AC. Run out of propane and this standard feature will power up the fridge at about 325 watt generator pull.

https://bensdiscountsupply.com/propa...rs-6-15-cu-ft/

The 6 & 8 cubic ft models use less gas than the 15 cubic ft units/
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Old 05-11-2018, 01:15 PM   #53
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I had a kerozene fridge and freezer on my sailboat. Worked well but used about 10 liters (2.5 gallons)a week in the tropics.
I have a multi fuel in my 5th wheel, uses about 30 lbs of propane a month if gas only.
On the boat, I had a Vitrifrigo (10 cu.in.) that quit recently. I replaced it with a Walmart style unit of the same size but first tested electric consumption as I had done with the Vitrifrigo.
Surprise, measured over one week, same place, same temp. outside and inside, the watt meter averaged about 480 W/day for each. The Vitrifrigo needed exactly the same energy than the cheap one! The cheap one runs on the inverter, so we can add 10% for efficiency loss but it is still a good deal.I know it may not last as long but I can buy 12 units for the price of the marine unit.
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