Home refrigerator in catamaran?

[a64pilot]

You don’t want an absorption fridge on a boat, on electricity they are way less efficient, and do have to be kept level, it has to do with the ammonia flow, not electric or propane.
Propane isn’t safe on a boat, unless you keep the fridge outside.

I don’t know if you would call them volatile gases or fuel gases, but flammable gases are being used as refrigerant now, good or bad, it works.

It’s not a new idea, been used for over 100 years I think.
https://climate.emerson.com/document...us-4204352.pdf

[Mike Banks]

I used a cheap K-Mart brand refrigerator on my tri for years--it drew about 75 watts when running, which equates to about 8 amps when fed through a large inverter. I think a true sine-wave inverter is essential if one wishes to use domestic devices aboard, such as hair dryers, blenders, decent sized fans etc--and the best ones are not cheap. One needs about 100 watts output at 240 volts.

The K-Mart brand was quite efficient as long as one only opened the door infrequently. Mostly it was used on a marina and I used two Engels 38 litre portable refrigerators when at sea because they were bin types, and did not spill their cold air every time the lid was opened.

When going to sea--the domestic one was left ashore to save weight. It was about the same usefulness as the Danfoss 12/24 volts new one when I first acquired the vessel. Not efficient enough to be run without mains support, because it was a cabinet type not a bin.

The domestic refrigerators require inverters--so unless one already has a large one already, one has to add that cost to the cheap purchase price of the refrigerator if one wishes to run a domestic type aboard.

As far as long term use was concerned--I still have it and it has been eight years now.

[leftbrainstuff]

Domestic appliancea arw power hogs regardless of the silly star ratings. If you run an inverter you effectively have many power sapping conversions. DC to DC to AC and probably back to DC again in the fridge. Also domestic appliances are likely to waste even more power when your batteries drop in voltage.

You also mention running on non standard refrigerant which will be even less effective at cooling.

Solar is so cheap these daya that the gas, DC and AC units fitted to RVs in the past are mostly redundant now.

We have 1kW of solar on our monohull and we run a dometic fridge, seperate freezer and an Engel. All from solar. We even heat our 6 gallon hot water from solar.

We have over provisioned our solar such that most sunny days we don't deploy all 3 panels or the mppt controllers lower the output once our batteries are charged. This reserve is great for days of no or infrequent sun.

[Mike Banks]

Mike Banks--I made a mistake in my post. One needs a 1000 watt inverter--not 100 as I stated. Sorry about that Chiefs-

[a64pilot]

If you look it up, propane is actually a pretty efficient refrigerant.
Problem is, it burns, and of course if there is a leak, well you know where it’s going.

[mikedefieslife]

Originally Posted by leftbrainstuff

Domestic appliancea arw power hogs regardless of the silly star ratings. If you run an inverter you effectively have many power sapping conversions. DC to DC to AC and probably back to DC again in the fridge. Also domestic appliances are likely to waste even more power when your batteries drop in voltage.

You also mention running on non standard refrigerant which will be even less effective at cooling.

Solar is so cheap these daya that the gas, DC and AC units fitted to RVs in the past are mostly redundant now.

We have 1kW of solar on our monohull and we run a dometic fridge, seperate freezer and an Engel. All from solar. We even heat our 6 gallon hot water from solar.

We have over provisioned our solar such that most sunny days we don't deploy all 3 panels or the mppt controllers lower the output once our batteries are charged. This reserve is great for days of no or infrequent sun.

I'm not denying this, but it would be interesting to see some comparisons with figures (inc. losses) for domestic vs marine/rv type fridges.

I mentioned in my post that the Liebherr UIKP 1550 is rated at drawing 168w per day. It's not like for like as the Liebherr has twice the capacity, but I have a Dometic CFX50 (a portable marine/rv type fridge/freezer). It's only A++ and is rated at 180w per day (AC).

https://www.dometic.com/en/se/produc...specifications

[myocean]

See my above mentioned thread including my last post there: Real world data from a unit on the yacht shows modern European fridges are indeed super efficient. (due to legal pressure from proper regulations made by the EU)

[valhalla360]

Originally Posted by davenrino

I have a Mono kept in a marina with shore power. Would these fridges have to be kept level if using 12v for day sails?

Yes, they do need to be level when in operation. The ammonia condenses in the system and falls to the bottom by gravity. If they are too far out of level, the ammonia doesn't flow correctly.

[valhalla360]

Originally Posted by a64pilot

You don’t want an absorption fridge on a boat, on electricity they are way less efficient, and do have to be kept level, it has to do with the ammonia flow, not electric or propane.
Propane isn’t safe on a boat, unless you keep the fridge outside.

We had one and loved it. On shore power, consumption is not a big deal and away from shore power a 20# tank lasts for weeks.

Yes, it has to be installed properly...same as propane stoves that most boats have...if you are going to say no propane system can be safe, we'll just have to agree to disagree.

[waterman46]

Originally Posted by Jef & Marin, Netherlands

Hi A64pilot,
Thanks for your answer, and for moving the thread.
The European fridge I am considering is a Liebherr 230 liter / 140 cm high having an official power consumption of 83 kWh per year. That is 1/4 of a kWh per day. The European fridges are now quite power efficient. Jef

This sounds better than my built-in reefer with it's 6 inches of insulation. 1/4 kWh per 24 hours would be only 10.4W power consumption on a continual basis (0.25kWh / 24h). The volume of 230 liter is equivalent to a very respectable cubic space of 60cm (about 2 feet) on each side. If running off an inverter, the continuous DC current would be about 1A at 12V for a total power consumption of 24AH per day. I would have to ask what internal and differential inside to outside temperatures, was this specified at?

[myocean]

Originally Posted by waterman46

I would have to ask what internal and differential inside to outside temperatures, was this specified at?

This is all defined in the EU regulation 1060/2010/EU which defines a reasonable ambient temperature ( https://eur-lex.europa.eu/LexUriServ...17:0046:EN:PDF ). There are 4 "climate classes" from "Temperate" to "Tropical". I think temperature range for the standard devices (temperate class) is 16°C to 32°C

.

[Jef & Marin, Netherlands]

Thanks to everybody this far, especially Ulf who has great practical experience with a 2012 European A++ model. We would take a state-of-the-art A+++ one.

I started the thread but could not follow it since we are sailing in French Polynesia where Internet is rare and slow. Additional input from people who already converted is of course appreciated.
I will start to select the model, and wonder how to get one from Europe to New Zealand where we will be coming cyclone season. And worry about the carpentry to the boat's interior.

And about the inverter; we use a lot of 230V appliances and the fridge might just switch on when the washing machine is in the heating cycle, overloading the system briefly.
Actually, we are so dependent on 230V that a fall-back inverter might be a good idea.


The boat and campervan fridges are old technology, and there is little R&D seeing the limited turnover. So they are not efficient like modern fridges. But they will have to invest, seeing that to stay legal they must switch to other coolant fluids than R134a.


About sailing magazines doing a comparison test between boat and domestic fridges: They have nothing to gain from this, and may loose advertising. So I am not surprised they will never mention this. However at the Grand Pavois La Rochelle boat show we have seen domestic fridges in some of the big charter catamarans.
Thanks again to all,
Jef

[Jef & Marin, Netherlands]

Hi all, I am in the process of deciding what to do.

I decided for a European model Liebherr IKBP2770 which is 230 liters; this is about the same as the sum of our present 2 fridges. (No I am not commercial). It is a fridge-only, we have a separate 90 liter freezer.

It takes a very low 67 kWh/year. This is an avarage power of 7.5 Watt.
67 kWh/year = 183.6 Wh per day.

At 13.2 Volt (Lithium) this is 13.9Ah/day.
But the official power figure is for non-opening at 25 centigrade. So it will not supply cold beer since you can not open it. To get a more realistic ballpark figure I double the Ahr's to 27.8Ah; adding 10% for inverter-loss gives 30.6 Ah. Then I add 10 Ahr because the inverter takes 5-6 Watts doing nothing.

Total will be 40 Ah, instead of the 90 Ah of our present set-up. This 90 Ah I measured while not living aboard; it would be higher with many openings.


The actual loss by having the inverter on 24/7 will be lower. In some cases it will already be on the whole night for our breadmaker; or for one of the many other appliances.


Great benefits: Lower power consumption, less than half; not having to defrost; and there is a big zero centigrade biofresh, keeping your fruit and veggies good much longer. Which is useful seeing the scarcity of finding fresh stuff here in the Pacific.


Now how to get that European model to New Zealand? Any suggestions? I already wrote an email to Liebherr New Zealand whether they are prepared to do a special order.

I'll keep you informed

[FlyingScot]

Just to clear up a point and confirm A64's post. RV / Caravan fridges that are ammonia based (absorption) use 12v, 110v or burning propane to heat the ammonia mixture to keep the liguid/gas moving through the system. If mounted outboard direction, which is typically they require +/- 3 degrees to work properly. Side to side (vehicle not fridge) they can work +/- 5 degrees. You can run one of these without using propane and simple use DC or AC. Problem is they aren't very efficient presuming you could keep them level.

Bali catamarans come with AC fridges (home style).

Many new RV / Caravans sold in the USA also come with home style fridges. AC only. Going down the road the engine makes plenty of power to use inverter. When stopped most are in a campground and plugged in. Or they can use the generator.

Many people were skeptical they would hold up to all the bouncing around, mainly the coils. I don't think they have a high failure rate. And since they are cheaper you can just replace as needed.

[Palarran]

I'm also considering replacing my refrigerator and freezer with a home unit. I'd probably go with one that has the drawer freezer on the bottom and french doors on the top with an ice maker.

My concern is shore power. I'm in the US, the boat is in the Bahamas. It would be difficult to get a 230v single phase unit here so it will have to be 120v - 60 hz. If we go to the EU, we may have trouble because the power is 50hz.

Maybe the solution would be to install an inverter sized just for the refrigerator

There's also this rv refrigerator that comes as 12v / 120v only - no propane.
https://www.thetford.com/product/2118-polarmax/