Refrigerator

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sbman said:
Well, the claim is that a particular brand of drawer fridge is 3X more efficient than a household fridge. This would be fantastic news, amazing in fact. Like saying you can drive a Volvo earth mover to Chicago on 200 gallons instead of 600 that the CAT uses.



At some point you run out of either energy input (in my case solar) or storage capacity (batteries) and a fridge using so much less power would be worth the money in that case even to someone cheap like me. Energy saved is energy you don't have to produce and store.
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Sbman, to clarify, I merely observed the manufacturers' specs of two like kind fridges, in this case, a domestic Summit 4.2 c.f. single door fridge compared to a Vitrifrigo 4.2 c.f. single door fridge. To be precise, I said that the specs show that the domestic fridge draws three times the number of watts when the fridge is running according to the manufacturer of each fridge. I did not make these numbers up. I got them from the spec sheets. Analogizing, what I am trying to understand is how an engine that uses three times as much fuel when running is not meaningful.

Or, how about a water pump. A pump that, when running, pumps 3 GPM is very likely to pump three times more water than a pump that pumps 1 GPM. And, big surprise, how much water is pumped is wholly dependent on how long the pumps run.
 
Theoretically it could be easily accounted for by noting that it "runs" less over a set time period to provide the same cooling factor. How it would accomplish that I don't know but could easily be explained by better insulation and heat dissipation? What am I missing? If you have 100 gallons of water to be pumped, if the 3 GPM pump uses more energy while running compared to the 1 GPM pump but accomplishes the task in 1/3 of the time and then shuts down to standby, it's pretty much a wash in power usage.
 
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Alaskaflyer said:
Theoretically it could be easily accounted for by noting that it "runs" less over a set time period to provide the same cooling factor. How it would accomplish that I don't know but could easily be explained by better insulation and heat dissipation? What am I missing? If you have 100 gallons of water to be pumped, if the 3 GPM pump uses more energy while running compared to the 1 GPM pump but accomplishes the task in 1/3 of the time and then shuts down to standby, it's pretty much a wash in power usage.
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Correct. The idea is to look at the amount of cooling the compressor can do with a given amount of power. So the more BTUs the compressor can move per watt hour, the more efficient. The other part is insulation. Better insulation means less heat needing to be removed from the box. The compressor duty cycle is almost irrelevant (identical fridge with a bigger compressor will simply run shorter cycles).
 
catalinajack said:
Sbman, to clarify, I merely observed the manufacturers' specs of two like kind fridges, in this case, a domestic Summit 4.2 c.f. single door fridge compared to a Vitrifrigo 4.2 c.f. single door fridge. To be precise, I said that the specs show that the domestic fridge draws three times the number of watts when the fridge is running according to the manufacturer of each fridge. I did not make these numbers up. I got them from the spec sheets.
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Wished you had written that earlier. The amperage specification on refrigerators isn't running amps of the compressor. The amperage rating is the maximum possible draw of the unit. It could be the starting amp draw of the compressor or the amperage draw on the defrost cycle. For a freezer equipped with an ice maker, it could include the compressor starting with the ice maker running and the light on in the refrigerator. Most appartment refrigerators use a rotary compressor which has less of a startup surge than a piston one, but there still is a substantial surge.

Ted
 
catalinajack said:
Sbman, to clarify, I merely observed the manufacturers' specs of two like kind fridges, in this case, a domestic Summit 4.2 c.f. single door fridge compared to a Vitrifrigo 4.2 c.f. single door fridge. To be precise, I said that the specs show that the domestic fridge draws three times the number of watts when the fridge is running according to the manufacturer of each fridge. I did not make these numbers up. I got them from the spec sheets. Analogizing, what I am trying to understand is how an engine that uses three times as much fuel when running is not meaningful.

Or, how about a water pump. A pump that, when running, pumps 3 GPM is very likely to pump three times more water than a pump that pumps 1 GPM. And, big surprise, how much water is pumped is wholly dependent on how long the pumps run.
Click to expand...

I do understand what you are saying and it's absolutely correct. The problem is that doesn't show the picture of the fridge, only the compressor. If you set those two compressors next to each other, one draws 3x more power than the other, absolutely. But, it's the system that is of interest as a whole, none of us have compressors sitting around running all the time, they are built into fridges, just like none of us have diesel engines sitting alone running, they are in boats to do work. Well most of us at least, I might have a lone diesel engine here or there from time to time.

Put each compressor in the same exact fridge, and assuming each has the overall cooling capacity to cool the box and are set to maintain the same temps they will average about the same power draw over time. The 3X one will run a lot less and the 1X will run a lot more, but the energy used to cool the box will be very similar, if they are of the same design it will be VERY close.

To evaluate a one fridge over another for off-grid use you need to know how much power it draws compared to others in similar conditions over a fixed period of time and divide that by the capacity of the fridge so you know how efficient it is at cooling each unit of capacity. You can compare a 1.2 cu/ft to a 14 cu/ft that way. You can compare a peltier to a compressor fridge that way, or even an absorption fridge running on electric.

My magic chef is 4.2 Wh per cu/ft at 75 degrees. The viti 2.8 drawer fridge is 2.8 Wh per cu/ft at 77 degrees, somewhat more efficient.

Given that, the household fridge is 1/3 freezer. I get 6.6 cu/ft fridge and 3.3 cu/ft freezer, so it's not a fair comparison giving the viti a significant advantage because it doesn't include a freezer area.

Freezing is much more energy intensive than refrigerating. To run two vitis, one as a 2.8 cu/ft fridge, and one as a 2.8 cu/ft freezer(5.6 cu/ft total) would require 1250 Wh /24 hours at 77 degrees per there specs, so it's 9.3 Wh/cu/ft/hr for the two, half as efficient as the household and still has less storage capacity in all respects.

My conclusion from this evaluation is that if you want a small fridge only, the viti 2.8 drawer would be a nice efficient choice in a convenient package that could fit in many situations others just wouldn't. It is also a stylish, modern looking appliance. It is not a good choice as a freezer, it does not have sufficient insulation to work efficiently at freezing temperatures and that is evidenced by it's high consumption when in freezer mode.
 
sbman said:
https://www.vitrifrigo.com/us/us/drw180a-all-in-one-single-compartment_2



The numbers Vitifrigo post are well within reason for their little drawer fridge. It's a bit more efficient overall than my household fridge. The numbers they post for it in freezer mode are terrible. They state 1.1 kWh/24h (12/24Vdc) for a small 2.8 cu/ft freezer. That's more power than my entire 9.9 fridge uses with a freezer about the same size attached.



Your test/measurement would be very interesting. 24 hours would be better, but 8 will tell some of the story. I am not skeptical of the numbers Vitifrigo posts, they sound correct. I'm not skeptical of energy star numbers either, I've measured enough fridges to know their testing is pretty accurate. I'm skeptical that any fridge is 3X more efficient than any other.



The Ah consumption is from my battery monitor, yes. Remember that Ah is a unit of Amps/Hour, but that is not power/hour because voltage is not included. Power is volts * amps = watts. Energy consumption is measured in Watts/hr = Wh. Your battery monitor integrates the data with samples taken multiple times per second which is helpful because neither voltage or current is stable, they vary. Integrating Volts*amps gives you the real picture.



If we were measuring your diesel engine and trying to compare our boats MPG, we would not take your idling fuel consumption, multiply it by the hours required to go a distance and then claim that's the boats MPG. Nor would we put it in gear against the anchor and, note it's fuel consumption and multiply that by a few hours to find the MPG. We'd motor up and down a measured course in both directions (to cancel out wind and current variations) a few times and make notes of the consumption to do so, divide by our fixed course distances, then we could compare notes on our MPGs. That would account for the entire system, hull design, propeller losses, engine design, weight, transmission losses, etc...
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My test numbers, as it turns out, I do not need to do a test. I happen to have a Balmar SG-200 battery monitor which shows precisely the number of amps being drawn from the batteries. I can report with certainty that the draw is 3.4 amps/ 41 watts. I will leave it to you guys to do the comparison. I am really curious, very curious what you conclude. From casual observation I estimate the duty cycle to be no more than 50%.

There is one issue that is very important irrespective of the nominal energy consumption. It is environmental. Some domestic fridges have their cooling coils embedded in their metal sides. Most enclosures have very little space between the sides of the fridge and the enclosure which severely limits air flow. I would caution anyone contemplating purchasing a domestic fridge to make certain that the cooling is in the back. Before I had the Vitrifrigo fridges, I had domestics. I replaced them after having had a reason to slide one of the domestics out of its enclosure and found the sides to be almost too hot touch. Not good.
 
sbman said:
I do understand what you are saying and it's absolutely correct. The problem is that doesn't show the picture of the fridge, only the compressor. If you set those two compressors next to each other, one draws 3x more power than the other, absolutely. But, it's the system that is of interest as a whole, none of us have compressors sitting around running all the time, they are built into fridges, just like none of us have diesel engines sitting alone running, they are in boats to do work. Well most of us at least, I might have a lone diesel engine here or there from time to time.



Put each compressor in the same exact fridge, and assuming each has the overall cooling capacity to cool the box and are set to maintain the same temps they will average about the same power draw over time. The 3X one will run a lot less and the 1X will run a lot more, but the energy used to cool the box will be very similar, if they are of the same design it will be VERY close.



To evaluate a one fridge over another for off-grid use you need to know how much power it draws compared to others in similar conditions over a fixed period of time and divide that by the capacity of the fridge so you know how efficient it is at cooling each unit of capacity. You can compare a 1.2 cu/ft to a 14 cu/ft that way. You can compare a peltier to a compressor fridge that way, or even an absorption fridge running on electric.



My magic chef is 4.2 Wh per cu/ft at 75 degrees. The viti 2.8 drawer fridge is 2.8 Wh per cu/ft at 77 degrees, somewhat more efficient.



Given that, the household fridge is 1/3 freezer. I get 6.6 cu/ft fridge and 3.3 cu/ft freezer, so it's not a fair comparison giving the viti a significant advantage because it doesn't include a freezer area.



Freezing is much more energy intensive than refrigerating. To run two vitis, one as a 2.8 cu/ft fridge, and one as a 2.8 cu/ft freezer(5.6 cu/ft total) would require 1250 Wh /24 hours at 77 degrees per there specs, so it's 9.3 Wh/cu/ft/hr for the two, half as efficient as the household and still has less storage capacity in all respects.



My conclusion from this evaluation is that if you want a small fridge only, the viti 2.8 drawer would be a nice efficient choice in a convenient package that could fit in many situations others just wouldn't. It is also a stylish, modern looking appliance. It is not a good choice as a freezer, it does not have sufficient insulation to work efficiently at freezing temperatures and that is evidenced by it's high consumption when in freezer mode.
Click to expand...
My magic chef is 4.2 Wh per cu/ft at 75 degrees. The viti 2.8 drawer fridge is 2.8 Wh per cu/ft at 77 degrees, somewhat more efficient.

To be precise, your Magic Chef consumes 50% more. Some folks would term that more than just "somewhat". Accounting for a 13% inverter loss, your number becomes 4.75 Wh per c.f. or 71% more. Now 71% is far different than the 300% I postulated but 71% is still a big number when one is concerned with battery bank capacity.
 
You guys are micro-analyzing to the n'th degree, but it has been an educational discussion. When I was overseas I investigated this subject and took energy measurements on the Samsung digital inverter fridge in my villa. Also communicated with technical support a few times.

The two things I was advised by them were (regarding domestic units):

(1) Don't add insulation board. You need that 1" air gap all around for cooling. Perhaps the condenser coils are bonded to the housing/skin of the fridge, but the entire skin conducts the heat and cools the coils, not just the immediate area where you feel the warmth. I suppose it wouldn't hurt to conduct some experiments, but nowadays we have the solar panels to make up for whatever small gains you could hope to achieve. However I think it would be beneficial to add additional insulation against the hull if your fridge is on an exterior wall, but still maintaining the air gap.

(2) The yellow tag, energy stickers, consumption estimates given by the manufacturers are actually quite accurate, averaged over the long term. If the sticker says 350 kWh of energy use annually, then you can pretty much plan on burning 1 kWh each day, and work that into your energy budget.
 
The test, here are the results. Ten hours overnight with a 20% addition for the fact that the main cabin is cooler overnight. Extrapolated to 24 hours, my two 4.2 cf Vitros consumed 110 amp-hours or 1.3 kilowatts. Certainly not precise but probably pretty damn close.
 
Keep in mind, the Vitrifrigo and other Danfoss compressor units are as good as it gets for purpose built marine units right now. Home units vary far more in power consumption (and suitability for install into an enclosure, like on a boat). So while some will be dramatically less efficient than the marine fridges, others won't be.

To get a true answer to which solution comes out on top, we'd have to figure out what the most efficient fridges available of each type are in a given size range, then account for which designs can accept added insulation and which can't. And then assess efficiency from there.
 
rslifkin said:
Keep in mind, the Vitrifrigo and other Danfoss compressor units are as good as it gets for purpose built marine units right now. Home units vary far more in power consumption (and suitability for install into an enclosure, like on a boat). So while some will be dramatically less efficient than the marine fridges, others won't be.

To get a true answer to which solution comes out on top, we'd have to figure out what the most efficient fridges available of each type are in a given size range, then account for which designs can accept added insulation and which can't. And then assess efficiency from there.
Click to expand...

While I'm not a fan of ABYC, this seems like a place where they could be consumer beneficial. If they required that boats meeting ABYC standards had to use appliances with Energy Guide decals, manufacturers would immediately test their appliances to the federal standard.

If you were building a new boat, wouldn't you want to have an idea of power consumption (energy efficiency) when picking refrigerators, water heaters, air conditioners, furnaces, engines, generators, and most other energy consuming components.

Ted
 
catalinajack said:
The test, here are the results. Ten hours overnight with a 20% addition for the fact that the main cabin is cooler overnight. Extrapolated to 24 hours, my two 4.2 cf Vitros consumed 110 amp-hours or 1.3 kilowatts. Certainly not precise but probably pretty damn close.
Click to expand...

That's some great information. So 2x4.2 units to get 8.4 cf using 1300 watts in 24 hours. You have one set to fridge and one set to freezer? Less efficient than my 9.9 at 1000W per 24 hours, but still within a good range and I'm sure they are a good fit in your cabin. Mine is strapped down so it doesn't walk around!

Your point about the 2.4 viti drawer is well understood. Given it's lack of features (no freezer) it is quite a bit more efficient than my larger combo household unit at doing a somewhat different job of fridge only. I do think it would make a good off-grid fridge solution for those that want a convenient drawer style fridge.

Also your point about the warm sides is a good thing for people to keep in mind, not all household fridges do this, but most are moving this way. They used to have an electric heating element inside the metal casing to prevent condensation, but this drew a lot of extra power. The new trend is to wrap some condenser lines around the inside of the casing and use their heat to keep the condensation down. This may be a bad thing if you have a tight space to fit a fridge into.

The overall conclusion here is that there is no magic bullet for refrigeration, there are differences and you can spend a little money or a lot of money and get similar results, if you are careful and want to do some research you can pick the best solution for your requirements from what's available. Or you can just buy something and let it do it's thing and not worry about it.
 
O C Diver said:
While I'm not a fan of ABYC, this seems like a place where they could be consumer beneficial. If they required that boats meeting ABYC standards had to use appliances with Energy Guide decals, manufacturers would immediately test their appliances to the federal standard.

If you were building a new boat, wouldn't you want to have an idea of power consumption (energy efficiency) when picking refrigerators, water heaters, air conditioners, furnaces, engines, generators, and most other energy consuming components.

Ted
Click to expand...

That's what drove the creation of the energy guide decals we have now, consumers had no idea how to compare one fridge to another or shop based on power savings. I'm surprised Vitifrigo publishes numbers for some of their fridges for 24 hours tested consumption, VERY FEW manufacturers do this unless required (energy guide).

Analyzing this stuff is only important if your goal is to work within a tight power budget. If you are on shore power most of the time and have a big genset for when you aren't, it doesn't matter much if your refrigeration is 1000W per day or 1500W per day. I've been selecting components for my boat with the goal of being off-grid and 100% solar powered aside from propulsion so I've put a lot of thought into how to accomplish that without spending a fortune.
 
rslifkin said:
Keep in mind, the Vitrifrigo and other Danfoss compressor units are as good as it gets for purpose built marine units right now. Home units vary far more in power consumption (and suitability for install into an enclosure, like on a boat). So while some will be dramatically less efficient than the marine fridges, others won't be.

To get a true answer to which solution comes out on top, we'd have to figure out what the most efficient fridges available of each type are in a given size range, then account for which designs can accept added insulation and which can't. And then assess efficiency from there.
Click to expand...

There are some specialty companies that create fridges that are built specifically to address this. The best components, extra thick insulation and documented results.

https://sundanzer.com/wp-content/uploads/2021/04/DCRF290-spec-sheet-.pdf

That's a 10.2 cu/ft fridge/freezer that only draws 500W/day in a 70 degree room, half what my household fridge uses. $1500

So if you want a truly low power solution you can order and wire up, it's already available.
 
I’ve read all the post and this is still my conclusion. The beer is ice cold, the ice cream is hard, the ice maker is making ice , I don’t have to defrost it and I’ve got enough house battery for my inverter to run it for at least 24 hrs before recharging. Summit FF1119SSIM
10.3 cu.ft. of space. Try one. You’ll love it!
 
sbman said:
That's some great information. So 2x4.2 units to get 8.4 cf using 1300 watts in 24 hours. You have one set to fridge and one set to freezer? Less efficient than my 9.9 at 1000W per 24 hours, but still within a good range and I'm sure they are a good fit in your cabin. Mine is strapped down so it doesn't walk around!



Your point about the 2.4 viti drawer is well understood. Given it's lack of features (no freezer) it is quite a bit more efficient than my larger combo household unit at doing a somewhat different job of fridge only. I do think it would make a good off-grid fridge solution for those that want a convenient drawer style fridge.



Also your point about the warm sides is a good thing for people to keep in mind, not all household fridges do this, but most are moving this way. They used to have an electric heating element inside the metal casing to prevent condensation, but this drew a lot of extra power. The new trend is to wrap some condenser lines around the inside of the casing and use their heat to keep the condensation down. This may be a bad thing if you have a tight space to fit a fridge into.



The overall conclusion here is that there is no magic bullet for refrigeration, there are differences and you can spend a little money or a lot of money and get similar results, if you are careful and want to do some research you can pick the best solution for your requirements from what's available. Or you can just buy something and let it do it's thing and not worry about it.
Click to expand...
Both of my units are refrigerator only, no freezer sections. We have a 5-cubic foot chest freezer on the flybridge.
 
Crazy how much energy is contained in a gallon of refined petroleum.

Tha'ts why a custom built reefer can use eutetic plates and only need to operate the engine every few (4 or 5) days.

Running an engine to make electric , pump it into a battery , then take it out to operate any compressor can never be truly efficient.

Although they can argue "mine is better than yours", none are really efficient.
 
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FF said:
Crazy how much energy is contained in a gallon of refined petroleum.

Tha'ts why a custom built reefer can use eutetic plates and only need to operate the engine every few (4 or 5) days.

Running an engine to make electric , pump it into a battery , then take it out to operate any compressor can never be truly efficient.
Click to expand...


Eutetic plates (if well implemented) might be a slightly more efficient energy storage medium, but it's a less flexible and often less practical solution. It made more sense when battery systems and the ability to charge them away from the dock hadn't evolved to the point we've reached now.
 
FF said:
Crazy how much energy is contained in a gallon of refined petroleum.

Tha'ts why a custom built reefer can use eutetic plates and only need to operate the engine every few (4 or 5) days.

Running an engine to make electric , pump it into a battery , then take it out to operate any compressor can never be truly efficient.

Although they can argue "mine is better than yours", none are really efficient.
Click to expand...

Hard to argue with the efficiency and long term economics of the sun to charge batteries and generate refrigeration.

Ted
 
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Propnut said:
It was a process, but the new refrigerator is installed and working great!View attachment 123021
Click to expand...



The Summit Refrigerator that I installed is one of the best improvements. It works flawlessly. Hard ice cream, cold beer, plenty of ice and it’s frost free. What more could you ask for? Highly recommend for anyone upgrading their refrigerator.
 
Propnut said:
It was a process, but the new refrigerator is installed and working great!View attachment 123021
Click to expand...

What model is this. I may be replacing my old frig soon. I need something close to 64" high but no over and I think it is 28" wide. With Ice maker for sure. I'd like a 12/120v but is s separate inverter the answer. Why not my current 3000 w inverter.
 
I’m interested in this also, I pulled out my 3 way fridge and am looking for a good alternative. Right now I just threw in a dorm fridge for when we are on shore power. I don’t have a house bank or inverter yet either.
 
For off grid applications, has anyone had success with Engel Freezers and Fridges?
 
bountyhunter44 said:
For off grid applications, has anyone had success with Engel Freezers and Fridges?
Click to expand...

I have an Engel MR040F. I use it as a supplemental freezer. While it's very good, it uses much more energy per cubic foot than my Summit refrigerator. Can't speak for how energy efficient it would be as a refrigerator.

Ted
 
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