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Old 06-04-2014, 20:21   #1
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Efficient Hhome Frigde/Freezer on a Boat?

I have the space, H 200x60x60cm (or +5cm to W and D).
What if I put the home fridge? Will take the efficient A+++ class model, run it off dedicated inverter (or the large invertor, which I will put anyway)?
Properly fix it, of course.

This was done on larger FP Sanya 57.





What are pro/cons? Why pay more?
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Old 06-04-2014, 22:21   #2
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Re: Efficient home frigde/freezer on a boat?

I run a small 120V fridge on a dedicated inverter. It uses 50-60 amps a day in 90 degree cabin temperatures. A larger Fridge is actually more efficient then a smaller fridge. So worst case about a KW a day. I use solar (230 watts) which provides all my modest electrical loads day to day.

From personal experience I found that a 120V fridge did not use any more amps per day then a 12V system. When running the 120V frige pulls lots more amps (14 for mine) but at 90 degree cabin temps it runs 10 minutes every hour in 2.5 minute chunks, for a amp draw per hour of 2.5 amps. Really not bad at all.

In the photos, I can tell you that fridges with ice/water in the door use more power on the order of 30 ish percent more. Due to heat gain through the ice door. SO the Fridge in the first photo would be more energy efficient.

As I have a sailboat, I installed a clasp that holds the door closed when healed over 20-30 degrees. I also securely mounted the fridge to the boat. From personal experence, sailing at 20 degree heal, does not adversly effect the compressor. Though probably due to wave action that keeps the oil moving about in the compressor.

Big issue is home fridges are not really designed for high heat areas. Mine handles 95 degree F cabin temps fine (100 degree outside temperatures). Though the UAE summer temps might cause problems if the cabin is not cooled.
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Old 07-04-2014, 00:26   #3
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Re: Efficient home frigde/freezer on a boat?

Very good feedback, thanks.
My cabin is air conditioned, so it is "like home" conditions. No heel. No hard bashing. Almost in the middle.

I will go on with A+++ energy efficient model. No ice doors for sure.
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Old 07-04-2014, 03:59   #4
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Re: Efficient home frigde/freezer on a boat?

I have a domestic fridge and freezer, have been running them for close to 5 years now. IMO they use a bit more power than a 12 volt built-in marine version would, but the cost savings are huge, more than enough to pay for additional solar panels to replace the power they use.

Reliability so far has been 100%, and if they fail, (although it would be rare for a domestic fridge to fail in less than 10 years) replacement is cheap and easy. I could replace either unit for less than the cost of just getting a fridge mechanic to the boat.

Newer household fridges are getting more and more energy efficient too.
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Old 07-04-2014, 04:14   #5
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Re: Efficient home frigde/freezer on a boat?

I just went through all the math, reading, research about doing this.

Turns out all I had to do was ask sailorchic34. She nailed it.

In my case, I compared built in 12v standard marine, to household refrigerator to 3 way propane refrigerator. I compared on a cost basis for installation, including extra components for solar, running them off generator, fuel consumption if on generator, propane costs and even what components i personally have on hand already.

I did the cost analysis for installation to yearly cost to 10 year cost.

Here is what i came up with.

12vdc standard install, normal marine,solar power. $6,222 install, same over 10 years, but life experience tells me those damn saltwater pumps, at $300 each, die every year when you use it full time. Not even considering it.Tired of all the maintenance and don't want the thru hull.

Standard house refrigerator install, running on solar only. $3250 install, $3250 cost over 10 years.

Propane running the 3 way refrigerator with a little bit of solar for house loads such as microwave and charging phones, anchor light, etc. $2050 install, $4450 over 10 years with cost of propane. $240 annual cost. Propane.

Running it all off a generator with house refrigerator. $2250 install with small, gasoline portable generator. $1800/ yr in fuel, $18,000 ovsr 10 years.Need to run gen every other day to keep up. Worst case does not consider free energy from motoring.

Final scenario. Running propane fridge, generating microwave and house power from a small gasoline generator. $2750 install cost, $720 a year in fuel, $9950 over 10 years.



I'm having a lot of trouble here because it costs much more to install the 100% solar system, but it is the cheapest in the long run. I prefer cheapest in the long run but an short on cash at the moment. Very difficult decision.
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Old 07-04-2014, 04:28   #6
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Re: Efficient home frigde/freezer on a boat?

Quote:
Originally Posted by sailorchic34 View Post
I run a small 120V fridge on a dedicated inverter. It uses 50-60 amps a day in 90 degree cabin temperatures. A larger Fridge is actually more efficient then a smaller fridge. So worst case about a KW a day. I use solar (230 watts) which provides all my modest electrical loads day to day.

From personal experience I found that a 120V fridge did not use any more amps per day then a 12V system. When running the 120V frige pulls lots more amps (14 for mine) but at 90 degree cabin temps it runs 10 minutes every hour in 2.5 minute chunks, for a amp draw per hour of 2.5 amps. Really not bad at all.

In the photos, I can tell you that fridges with ice/water in the door use more power on the order of 30 ish percent more. Due to heat gain through the ice door. SO the Fridge in the first photo would be more energy efficient.

As I have a sailboat, I installed a clasp that holds the door closed when healed over 20-30 degrees. I also securely mounted the fridge to the boat. From personal experence, sailing at 20 degree heal, does not adversly effect the compressor. Though probably due to wave action that keeps the oil moving about in the compressor.

Big issue is home fridges are not really designed for high heat areas. Mine handles 95 degree F cabin temps fine (100 degree outside temperatures). Though the UAE summer temps might cause problems if the cabin is not cooled.
Excellent info!

This is all hypothetical as I don't have a boat yet, but I was thinking of installing a 120v chest type freezer and setting the existing fridge/freezer as 2 fridges.
My question is, with a chest type unit, you don't lose much cold air when you open the door, but an upright seems to lose a lot of cold air. It seems to me that an upright would run a lot more per day if you're in and out of it, compared to a chest type unit.

Did you install an upright? What do you think?
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Old 07-04-2014, 05:09   #7
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Re: Efficient home frigde/freezer on a boat?

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Originally Posted by socaldmax View Post
Excellent info!

This is all hypothetical as I don't have a boat yet, but I was thinking of installing a 120v chest type freezer and setting the existing fridge/freezer as 2 fridges.
My question is, with a chest type unit, you don't lose much cold air when you open the door, but an upright seems to lose a lot of cold air. It seems to me that an upright would run a lot more per day if you're in and out of it, compared to a chest type unit.

Did you install an upright? What do you think?
The more energy efficient solution is to get a bigger single refrigerator/freezer. You will use double the power installing a second unit. Increase the size of the single unit.

Further, the cold air loss is negligible with an upright when contrasted with the pain in the %ss of digging through a deep pit to find things. This is an old wives tale. See, this has to do with the physical property "specific heat." When some cold air drops out of a refrigerator, it raises the temp of the air inside just a little bit. But, the food, liquids,refrigerator interior surfaces,shelves, etc... do not change temperature, unless you are sitting there like an idiot with the door open trying to look at what you want to eat.

So, you are only introducing a moment or 2 of compressor work by changing the air because while the air raises slightly in temperature, the things that are most difficult and energy consuming to cool (the food, shelves, lining of the refrigerator), do not need additional cooling from you opening the door.

Expense and energy consumption are basically the same foir both. So why have to suffer through digging in pit?

Lastly, the amount of time you have to keep the damn pit open, coupled withthe need to take half of the stuff in the pit out and put it on the counter while digging COMPLETELY negates any advantage of air not spilling out. Opening a front loader, instantly grabbing the item and closing the door wastes less energy than piling all the food on the counter, where all those higher specific heat items soak up heat.

It's a wives tale, imo, made up by people who do not actually live on boats and who probably are just weekenders getting a sandwich out of an empty pit refrigerator. In real life on boats, the energy lossses from digging are substantial.
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Old 07-04-2014, 12:15   #8
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Re: Efficient home frigde/freezer on a boat?

Quote:
Originally Posted by oceannavigator View Post
The more energy efficient solution is to get a bigger single refrigerator/freezer. You will use double the power installing a second unit. Increase the size of the single unit.

Further, the cold air loss is negligible with an upright when contrasted with the pain in the %ss of digging through a deep pit to find things. This is an old wives tale. See, this has to do with the physical property "specific heat." When some cold air drops out of a refrigerator, it raises the temp of the air inside just a little bit. But, the food, liquids,refrigerator interior surfaces,shelves, etc... do not change temperature, unless you are sitting there like an idiot with the door open trying to look at what you want to eat.

So, you are only introducing a moment or 2 of compressor work by changing the air because while the air raises slightly in temperature, the things that are most difficult and energy consuming to cool (the food, shelves, lining of the refrigerator), do not need additional cooling from you opening the door.

Expense and energy consumption are basically the same foir both. So why have to suffer through digging in pit?

Lastly, the amount of time you have to keep the damn pit open, coupled withthe need to take half of the stuff in the pit out and put it on the counter while digging COMPLETELY negates any advantage of air not spilling out. Opening a front loader, instantly grabbing the item and closing the door wastes less energy than piling all the food on the counter, where all those higher specific heat items soak up heat.

It's a wives tale, imo, made up by people who do not actually live on boats and who probably are just weekenders getting a sandwich out of an empty pit refrigerator. In real life on boats, the energy lossses from digging are substantial.
That's a valid, practical comparison.
But don't forget about the additional water (vapor)/humidity added by opening the door and exchanging those cubic feet of cold dry air for warm wet air; at least in sea level, humid climes, and warm air contains much more moisture per cubic volume. That water vapor will be frozen out. It takes beaucoup energy to do that, relatively, and will form the dreaded 'frost bunny' (assuming that most of those small domestic iceboxes are non-self-defrosting).
That said, I went with one of those small ones long ago, and like sailorchic, am happy with the tradeoff (only paid $54 for it new, pretty hard to beat that cost analysis...).
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Old 07-04-2014, 13:11   #9
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Re: Efficient home frigde/freezer on a boat?

Quote:
Originally Posted by oceannavigator View Post
I just went through all the math, reading, research about doing this.

Turns out all I had to do was ask sailorchic34. She nailed it.

In my case, I compared built in 12v standard marine, to household refrigerator to 3 way propane refrigerator. I compared on a cost basis for installation, including extra components for solar, running them off generator, fuel consumption if on generator, propane costs and even what components i personally have on hand already.

I did the cost analysis for installation to yearly cost to 10 year cost.

Here is what i came up with.

12vdc standard install, normal marine,solar power. $6,222 install, same over 10 years, but life experience tells me those damn saltwater pumps, at $300 each, die every year when you use it full time. Not even considering it.Tired of all the maintenance and don't want the thru hull.

Standard house refrigerator install, running on solar only. $3250 install, $3250 cost over 10 years.

Propane running the 3 way refrigerator with a little bit of solar for house loads such as microwave and charging phones, anchor light, etc. $2050 install, $4450 over 10 years with cost of propane. $240 annual cost. Propane.

Running it all off a generator with house refrigerator. $2250 install with small, gasoline portable generator. $1800/ yr in fuel, $18,000 ovsr 10 years.Need to run gen every other day to keep up. Worst case does not consider free energy from motoring.

Final scenario. Running propane fridge, generating microwave and house power from a small gasoline generator. $2750 install cost, $720 a year in fuel, $9950 over 10 years.



I'm having a lot of trouble here because it costs much more to install the 100% solar system, but it is the cheapest in the long run. I prefer cheapest in the long run but an short on cash at the moment. Very difficult decision.
I did the same comparisons and came out with some slightly different conclusions.

- Because of reliability issues and cost I went with an air cooled, marine 12V system. No water pump to repair or replace and eliminates some potential corrosion issues. Paid about $2000 for high end, large capacity system. I did build and insulate my own box which would have added at least a thousand or so to the cost.

- I have a 9-10 cu ft box and in FL summer, 90-95 temps in the cabin I was using 45-50 amp hours/day. Guess my insulation job worked out OK.

- With solar, high output alternator and a small generator for backup my energy budget should be small.
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Old 07-04-2014, 15:17   #10
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Re: Efficient home frigde/freezer on a boat?

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Originally Posted by skipmac View Post
I did the same comparisons and came out with some slightly different conclusions.

- Because of reliability issues and cost I went with an air cooled, marine 12V system. No water pump to repair or replace and eliminates some potential corrosion issues. Paid about $2000 for high end, large capacity system. I did build and insulate my own box which would have added at least a thousand or so to the cost.

- I have a 9-10 cu ft box and in FL summer, 90-95 temps in the cabin I was using 45-50 amp hours/day. Guess my insulation job worked out OK.

- With solar, high output alternator and a small generator for backup my energy budget should be small.

Ahhh! Forgot to put that one in. It was on my spreadsheet. A good choice.

I should mention that my numbers are very specific to my own situation. I have a blank canvas. No systems yet. So, these costs were to produce power for incidentals, plus refrigerator, varying power sources and refrigerator types.

Everyone really has to do their own calculations sine maybe you already have a 2KW solar array or 2,000 gallons of fuel in a bunker somewhere.
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Old 07-04-2014, 15:37   #11
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Re: Efficient home frigde/freezer on a boat?

Quote:
Originally Posted by skipmac View Post
I did the same comparisons and came out with some slightly different conclusions.

- Because of reliability issues and cost I went with an air cooled, marine 12V system. No water pump to repair or replace and eliminates some potential corrosion issues. Paid about $2000 for high end, large capacity system. I did build and insulate my own box which would have added at least a thousand or so to the cost.

- I have a 9-10 cu ft box and in FL summer, 90-95 temps in the cabin I was using 45-50 amp hours/day. Guess my insulation job worked out OK.

- With solar, high output alternator and a small generator for backup my energy budget should be small.

Skipmac,

Did you insulate the box with Areogel? Sorry, I tried looking at your past post, man, you've got a lot. Those are impressive numbers for a box that big, at those temps.
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Old 07-04-2014, 15:40   #12
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Re: Efficient home frigde/freezer on a boat?

Here is some real life date...although these smaller refrigeration units are not what you are looking for, you will see the same type of power problems.
http://www.cruiserowaterandpower.com/EcoFridge.html

We have converted dozzens of 120v refrigerators to 12v and almost every one we test results in a 1/3 the power draw once we put in the 12v compressor over the 120v.

Two big reasons:
1. Even the best energy start 120v compressor is horribly less efficient as the moden 12v compressors. They are popped out without regard to true energy efficiency but just want to get the "energy start" rating...IE doing the bare minimum necessary because people don't really buy a 120v refrigerator these days based on energy usage data..but on price/looks and features.

2. Anytime you power something through an inverter you have an efficiency loss

Now none of this really matters with a 2000W solar array, but for mose boats without a crazy amount of solar powering their refrigerator and freezer is the No 1 battery sucker on their boat. We won't even talk about the energy loss every time you open the door and the cold air spilled out on your feet replaced by warm moist air.....that right there has caused a 30% efficiency loss in our testing.
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Old 07-04-2014, 15:41   #13
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Re: Efficient home frigde/freezer on a boat?

Here is some real life date...although these smaller refrigeration units are not what you are looking for, you will see the same type of power problems.
EcoFridge 12v/24v Solar Powered Upright Refrigerator and Freezers

We have converted dozzens of 120v refrigerators to 12v and almost every one we test results in a 1/3 the power draw once we put in the 12v compressor over the 120v.

Two big reasons:
1. Even the best energy start 120v compressor is horribly less efficient as the moden 12v compressors. They are popped out without regard to true energy efficiency but just want to get the "energy start" rating...IE doing the bare minimum necessary because people don't really buy a 120v refrigerator these days based on energy usage data..but on price/looks and features.

2. Anytime you power something through an inverter you have an efficiency loss

Now none of this really matters with a 2000W solar array, but for mose boats without a crazy amount of solar powering their refrigerator and freezer is the No 1 battery sucker on their boat. We won't even talk about the energy loss every time you open the door and the cold air spilled out on your feet replaced by warm moist air.....that right there has caused a 30% efficiency loss in our testing.
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Old 07-04-2014, 15:56   #14
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Re: Efficient home frigde/freezer on a boat?

The one thing that may have been missed on the propane fridge is: they seem to often be brokedown on travel trailers/motorhomes (cost?), the danger of the always "on" propane aplliance in the cabin, the trouble of getting propane all the time (they use it pretty fast).
Doors:
I've had front door, refrig with front and top doors, and top loading only. Frankly I couldnt determine any differnce in power use from the doors. Maybe if you have kids that will open the door and stand there for 5 mins it would matter. It does make a diff frost wise though... must defrost more often on a front door model.
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Old 07-04-2014, 16:03   #15
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Re: Efficient home frigde/freezer on a boat?

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Here is some real life date...although these smaller refrigeration units are not what you are looking for, you will see the same type of power problems.
EcoFridge 12v/24v Solar Powered Upright Refrigerator and Freezers

We have converted dozzens of 120v refrigerators to 12v and almost every one we test results in a 1/3 the power draw once we put in the 12v compressor over the 120v.
So... sorry to be a skeptic but... what you're saying is.. you bid a job, and if it goes like they usually do, the workman takes a lot longer to get it done than bid, then you take a few days on the boat just to determine the power savings? You're kidding right? or is this a hobby?
Can you show us the data and tell us how you determine this savings?
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