Home refrigerator in catamaran?

[Bruce K]

Originally Posted by CatNewBee

It is the concentration in the atmosphere, more CO2 means less Oxygen to breathe.

Without CO2 you would not breathe, check physiology of breathing, no more poisionus than nitrogen

[CatNewBee]

That is why on all plastic bags in the US are warnings, that kids should not put them on their head to not get suffocated. Don't try this at home!

[flyingfin]

12V refrigerators are worthless unless on board a vessel that has engine or generator that runs 24 hours per day.

[CatNewBee]

Originally Posted by flyingfin

12V refrigerators are worthless unless on board a vessel that has engine or generator that runs 24 hours per day.

Some solar-panel with a controller and a decent storage (battery bank) and you can endless cool your food without engine run time or generator use (as we do on our cat with 2 fridges and one freezer - all of them 12V, plus induction cooking and electric baking, water making, washing clothes, making ice cubes, brewing coffee, making ice cream) with enough resilience for 3-4 days bad weather.

So not that bad as long as the sun shines where you cruise.

[Cadence]

Originally Posted by Bruce K

I had a propane/AC refrigerator on my previous 50' mono motorsailer, many, many "experts" told me it would not work; I only had the boat for 10 years, and was still waiting for the fridge not to work when I sold the boat. A 9kg tank of propane lasted 3 to 4 weeks, including my stove and BBQ use.

I think many bash absorption units because they have never had one. As to being level, yes if you are stationary if your sloshing the ammonia around in the tank, for lack of a better term, not that important. The orientation of the cylindrical tank containing the ammonia fore and aft or athwart ships is probably key depending on the particular boats motion. JMHO

And I expect a lot of backlash. It is only an opinion.

[44'cruisingcat]

Originally Posted by CatNewBee

I guess, you can prove this statement by some hard facts?

The OP's inverter draws 5 Watts at idle. Ours draws about 6. Under 1/2 an amp. Nowhere near 40 - 50 amp hours a day. Our 100 litre freezer plus the inverter only draws about 50 amp hours per day.

Household fridges are getting much more efficient. Much better insulation, and some are now using inverter technology to run their compressors. This is because many buyers are now basing their choice on power consumption figures.

[rom]

@Dsanduril thank you for the detailed feedback, very informative and pretty much what I was expecting. About to purchase a pair of liebherr myself. Only A++ though, as they don't make the 150l stainless steel finish in A+++ unfortunately.


Catnewbee ?? someone stole your account ?

[CatNewBee]

Originally Posted by rom

Catnewbee ?? someone stole your account ?

What?

[CatNewBee]

Originally Posted by 44'cruisingcat

The OP's inverter draws 5 Watts at idle. Ours draws about 6. Under 1/2 an amp. Nowhere near 40 - 50 amp hours a day. Our 100 litre freezer plus the inverter only draws about 50 amp hours per day.

Household fridges are getting much more efficient. Much better insulation, and some are now using inverter technology to run their compressors. This is because many buyers are now basing their choice on power consumption figures.

6 Watt at idle are still 12Ah / day for the inverter. My inverter draws 3A at idle (it is a 5000W unit), so my would blow 72Ah for being always on. So the range is a little larger than assumed (12Ah-72Ah per day for Inverter between 300W and 5000W), I had a 1000W unit on my mind for the two fridges/freezer - this was the base of my estimation, I was not aware they would work with a 300W inverter especially because the compressors have a peak draw when starting. Good to know, the 300W can cope with this currents reliably.

Btw. 50Ah / day are very good values for a freezer given 10-12Ah being inverter losses.

My 3 12V units draw together almost constantly 15A all day long, so 360Ah/day - they are set to maximum cooling.

[noelex 77]

Originally Posted by CatNewBee

My inverter draws 3A at idle (it is a 5000W unit), so my would blow 72Ah for being always on.

This is adjustable on many of the newer, larger inverters.

The inverters have power saving options that can be selected with jumpers or with software.

In simple terms, the idea is that on the higher power saving options the inverter will go to sleep, waking up periodically to detect if any load is present. If there is a load the inverter wakes up. In some intermediate modes the inverter supplies a reduced voltage in sleep mode to prevent connected devices initiating a start up procedure when the power is reconnected.

Drawbacks are that small loads may not turn the inverter on and that there can sometimes be a slight delay before devices power up. It does not reduce the power consumed when operating, only when there is no load.

Some devices have a permanent power draw, which can stop the inverter entering the sleep mode, so the setting would not necessarily help with a fridge, but would be worth a try.

Even without the power saving options, many modern inverters consume much less power than the 3A required for your unit.

Particularly if living on solar power it is worth looking carefully at the power consumption of equipment. There can be very significant differences between otherwise similar devices from different manufacturers.

An example is my Mastervolt 2500w inverter.
With no load, without any power saving function it consumes 0.25A @24v. This drops to 0.025A with full power saving.

[CatNewBee]

Hi, yes, I am aware of this, my Victron Quattro has also the two power saving options, but they do not work efficiently enough with residential fancy devices.

The reduced voltage option almost has no benefit - it reduces current only by 0.3...0.5A, the other option confuses the galley appliances, they have displays and touch sensors that would make them unusable if the inverter switches on and off frequently. Especially the oven needs some settings by the touch display (select heating program, temperature, duration) before you hit the button to start operation and switching off and on reboots the UI - so one cannot make a reliable setting, the induction cook-top also relies on touch buttons that do not work or do not work reliably on power saving settings.

I assume same would be for a fridges, because the temperature electronics, sensors etc need to run all the time, so power saving on the inverter may confuse the operation, residential devices rely more and more on stable power supplies in contrast to the old bi-metal regulated fridges.

[44'cruisingcat]

Originally Posted by CatNewBee

6 Watt at idle are still 12Ah / day for the inverter. My inverter draws 3A at idle (it is a 5000W unit), so my would blow 72Ah for being always on. So the range is a little larger than assumed (12Ah-72Ah per day for Inverter between 300W and 5000W), I had a 1000W unit on my mind for the two fridges/freezer - this was the base of my estimation, I was not aware they would work with a 300W inverter especially because the compressors have a peak draw when starting. Good to know, the 300W can cope with this currents reliably.

Btw. 50Ah / day are very good values for a freezer given 10-12Ah being inverter losses.

My 3 12V units draw together almost constantly 15A all day long, so 360Ah/day - they are set to maximum cooling.

No need for such a big inverter to run a fridge. Mine is 1000W, can supposedly handle 2000 momentarily. The fridge and freezer compressors are 60 Watt, so possibly 600 Watt for a moment on start up.

The inverter draws less than 1/2 amp when idle, but that doesn't necessarily mean that 12 amps are lost. When a fridge is running some or most of that 1/2 amp could be being put to use.

The fact is, domestic fridges and freezers ARE getting more efficient. Market forces are driving this. As power prices rise, inefficient appliences will become impossible to sell.

Unfortunately, I don't think the same can be said for marine appliances. IMO "Marine" is often shorthand for overpriced garbage.

My freezer cost $300, the fridge, $250. Both have been faultless for 8 1/2 years virtually non stop. Many people with marine fridges have been envious of this reliability. Most have spent far more than that on repairs... as soon as the fridge guy sets foot on your boat, it's probably going to cost you more than a new fridge would cost me...

[Palarran]

It's hard to believe that a regular home refrigerator only draws 60 watts when running. At 120v that's .5 amps. But I totally agree with the rest of your post.

Of all the electricity-powered household appliances, your refrigerator uses the second largest amount of energy, after the air conditioner. According to the U.S. Department of Energy, the average refrigerator uses approximately 725 watts of electricity and 15 to 20 amps, which can equal 10 percent or more of your home's total energy usage.

[Uncle Bob]

Originally Posted by flyingfin

12V refrigerators are worthless unless on board a vessel that has engine or generator that runs 24 hours per day.

[nebster]

Originally Posted by Palarran

It's hard to believe that a regular home refrigerator only draws 60 watts when running. At 120v that's .5 amps. But I totally agree with the rest of your post.

Of all the electricity-powered household appliances, your refrigerator uses the second largest amount of energy, after the air conditioner. According to the U.S. Department of Energy, the average refrigerator uses approximately 725 watts of electricity and 15 to 20 amps, which can equal 10 percent or more of your home's total energy usage.

A modern residential refrigerator consumes about 1kWh per day with typical usage. The best ones come in at around 0.8kWh per day.

They are very efficient for their volume.

As a side note, the person you quoted doesn't understand the difference between power and energy. That's something that it seems might be important when writing on this topic.