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Refrigerator: Best Power Source (if there is a single one......)


Greg K

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As I'm not a boat owner, I'm a bit sheepish to post questions to satisfy my general curiosity.  However I'm a curious about a few things and appreciate any replies.

 

So...let's talk refrigerators.  Dug through this forum on equipment, good information on refrigeration.  There are a few ways to power them from the very little I know.  12V seems popular.  How about propane gas, not so much?  Those w/ shore power hook ups can enjoy a standard 240v I suppose.

 

And w/ anything narrow boat, I'm beginning to understand that HOW you will be using the boat will dictate a bit about mechanicals and the like.  Such as, are you doing short jaunts of a week or so, extended cruising, or simply enjoying your slip at the boatyard?

 

Thanks in advance for the replies.

 

Cheers!

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Gas is by far the most convenient as leccy fridges gobble the power, but probably the most dangerous too though. Not sure if BSS allows them on boats.

 

Always good for ten pages of arguments about it!

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I will jump in.

 

Electricity away from a shoreline is basically in short supply and expensive to produce unless you have a lot of solar and the weather to suit so for me electricity be it 240v AC  or 12v DC is the second choice.

 

Propane/Butane was very popular, but The Boat Safety Scheme has more or less banned it for petrol powered boats. It is easier for diesel powered boats, but as far as I know there are no manufactures of fridges now that approve them for boat use so that causes problems for the latest set of regulations boats must conform to. So back to electricity.

 

When away from a shore line, a 240V AC fridge requires another bit of equipment to convert 12V DC to 240V AC so that is an extra cost in electricity just to make the thing work plus the initial purchase. However, 12V fridges are expensive or very expensive compared with domestic ones so the cost of the extra inverter may still make a mains fridge cheaper and nowadays buying a quality inverter (12V to 240V) may not cost much more and if you ensure you buy the most efficient mains fridge the electricity used may be very similar.

 

Finally, the clever boaters are buying small domestic freezers and fitting a fridge type thermostat because the extra thermal insulation makes that setup use less electricity than a fridge running at the same temperature.

 

If I had an off grid property, it would be gas for me every time.

Edited by Tony Brooks
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12V or 24 V  is where you start for all compressor fridges.  Some prefer to use an inverter and a 230V appliance, some to use a  low voltage appliance.  The choice is down to preference, existing equipment  and lifestyle.

 

Compressor fridges are much more efficient than absorption ones, which is one why gas (or paraffin!) fridges are less common than they were. Another is that decent sized ones are scarce.  There can also be boat safety scheme issues.

Electric absorption fridges exist, but use so much power that they are not practical except on a permanent land line, when a mains compressor fridge would be better anyway.

N

 

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I have a 12v fridge (with ice box) and a 230v Freezer, then if the 230v inverter goes 'bang' I can still keep a bit of frozen stuff in the fridge icebox.

If the fridge goes 'bang' I can put the stuff from the ice box in the freezer and the stuff that needs keeping cool in a bag hanging over the side, or, in the bilges under the floor.

 

On a boat always try and have 2-ways of doing everything.

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1 hour ago, Tony Brooks said:

but as far as I know there are no manufactures of fridges now that approve them for boat use so that causes problems for the latest set of regulations boats must conform to.

There are gas fridges approved by the manufacturers for use in caravans and RVs. In practice the conditions on a narrow boat are little different, and so there should be no problem, but as soon as the words 'boat' or 'marine' appear manufacturers think of small boats being tossed about on open seas, and conclude that the cost of designing out the additional risks are not worth the effort, so they just say 'not suitable for boats'. The UK canal boat market isn't big enough for them to make the effort for a specific exemption from the 'no boats' rule.

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8 minutes ago, David Mack said:

There are gas fridges approved by the manufacturers for use in caravans and RVs. In practice the conditions on a narrow boat are little different, and so there should be no problem, but as soon as the words 'boat' or 'marine' appear manufacturers think of small boats being tossed about on open seas, and conclude that the cost of designing out the additional risks are not worth the effort, so they just say 'not suitable for boats'. The UK canal boat market isn't big enough for them to make the effort for a specific exemption from the 'no boats' rule.

 

All true, but If a bit of equipment is not marked as suitable for use in a boat, then the RCR/RCD might be illegal or false. As Alan keeps telling us, the RCR/RCD is now for the life of the boat, so fitting a gas fridge for a post 1996 boat (when the RCD came into effect) would likely invalidate the RCD?RCR certification. I know that has little importance for many inland boaters and many are happy to ignore such things, but it could have consequences in the future.

 

To my mind its typical EU type regulation for the sake of it for inland  boats, but that is what we have and what we need to live with.

Edited by Tony Brooks
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Getting back to the immediate subject, if the OP decides on a cheap, run-of-the-mill 240Vac domestic under-counter fridge instead of a £600 12Vdc one, which make and model of inverter does the team suggest to run it? 

 

(Assuming this is to be a dedicated inverter for the fridge and nothing else.)

 

Can u guess why I ask? 😄

Edited by MtB
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I think I would use a dedicated inverter, other than the main boat's inverter. What are the power requirements of the fridge - about 45watts. So, something along the lines of a 150w pure sine wave. ?? Mains under the counter fridge with coolbox, power usage of about 130 Kwh per year. Any advances on that approximation?

 

This one looks ok. Not too pricey, from Midland Chandlers. 

VV-041-1593662143.jpg.94b01d75c37d52e17a8232643c034f30.jpg

Yes, it does add to the cost of the fridge, but well under the cost of a new 12v fridge. Smeg sell an under the counter frige/coolbox for £179, good power rating,  and the inverter in about £160. Plus cabling, etc. 

 

Fridge: Smeg FS08WF

 

 

Edited by Higgs
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I have just fitted a LEC 12/24volt fridge freezer it replaced a shoreline it uses less electric than the shoreline must be down to better insulation or gas? It bigger as well  double bonus. I have a 3 way fridge in our camper van and it eats electric and gas, on campergaz bottles its cheaper to buy fresh than try to store it in the fridge!

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When I had a gas fridge on my first boat, it sipped the gas most parsimoniously. We changed the gas bottle about once every six weeks IIRC, fridge, cooker, Paloma water heater all running off it.  

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1 minute ago, MtB said:

When I had a gas fridge on my first boat, it sipped the gas most parsimoniously. We changed the gas bottle about once every six weeks IIRC, fridge, cooker, Paloma water heater all running off it.  

Its the price of the gas bottles that's the issue works out at about  a tenner a litre or more 😱

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Just now, peterboat said:

Its the price of the gas bottles that's the issue works out at about  a tenner a litre or more 😱

 

You should get s solar panel fitted to your boat 🤣

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1 hour ago, MtB said:

Getting back to the immediate subject, if the OP decides on a cheap, run-of-the-mill 240Vac domestic under-counter fridge instead of a £600 12Vdc one, which make and model of inverter does the team suggest to run it? 

 

(Assuming this is to be a dedicated inverter for the fridge and nothing else.)

 

Can u guess why I ask? 😄

This is the way we have gone, very large 240v Lieberhh A++ fridge, and a 1200w dedicated PSW inverter. Heard the inverter fan for the first time last week when it was 32C outside.

I am however looking at replacing with a 3kw PSW to run the Belling oven/hob too, the Belling Grill doesnt like the MSW flow and the ignition spark tries to keep going forever.

Edited by matty40s
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Just now, matty40s said:

This is the way we have gone, very large 240v Lieberhh A++ fridge, and a 1200w dedicated PSW inverter. Heard the inverter fan for the first time last week when it was 32C outside.

 

Thanks. 

 

 

This runs happily on solar for 9 months of the year I imagine? How much solar do you have?

 

(This raises another point. I added two 100W Victron panels to my single 100W Vikram, and they made hardly any difference!! One for another thread though...)

 

 

 

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19 minutes ago, MtB said:

 

You should get s solar panel fitted to your boat 🤣

I have a 200 watt one on the camper it can't supply the fridge with enough lecce it needs the engine running! My mate has a compressor fridge in his type 25 the solar easily runs it, 3 way fridges are crap! They eat electric. In reality because we use the camper so little it doesn't matter but if that changes an underfloor refillable gas is on the cards 

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Apologies in advance as I have limited experience, but these are a couple of the issues I recall being discussed: 

 

The guy below on youtube did a comparison test of 12v and 240v fridges, and with an inverter that is not too 'greedy' (i.e. doesnt draw too much current itself), the energy use is not vastly different. He determined that the presence or absence of a freezer compartment was a bigger factor in energy usage than the issue of 12c vs 240v. 

 

I also recall some folks mentioning that the standard of insulation on some 12v fridges was not great, and that 240v fridges with multiple energy star ratings are more energy efficient than a 12v fridge that is not well-insulated- perhaps the regulations for 12v fridges are less stringent in some way.

Perhaps a safe choice (if you do not have detailed knowledge about a particular 12v fridge and its insulation) would be a high-rated 240v fridge that has been converted to 12v, e.g. one of the LEC models.  

 

Regarding the significant energy drain of a fridge, in my case the solar panels usually collect more than enough power to run the fridge and everything else for 8 months of the year.

I've been moored at the same spot for I think the last 5 or 6 days, and not once had to run the engine for electricity.

In the colder months, with little solar, you either switch the the fridge off and stick your food/beer in a bag in the (cold) cratch, or else you bite the bullet and just run the engine more, in order to replace the consumed electricity. 

I think its very worthwhile checking out the charging system of any boat you're interested in. In my case its not that great, and I'm looking to upgrade my charging setup before the end of Sept (although its not a quick matter to get a knowledgeable pro to do the job), so that I'll be able to replace the consumed electricity of the fridge (maybe 40-50Ah per day) in less than 30 mins of engine running, instead of 60-80 mins as it takes currently. 

 

PS- on the subject of powering a 240v fridge: I upgraded from a 1800w Sterling modified sine wave inverter to a cheap and cheerful 2000watt pure sine model from Amazon (because a couple of latptop power supplies and batteries were damaged by the modified sine wave), and one of the unexpected side effects was that the fan hardly ever needs to run on the new one. 

The 1800 watt model used to  have a noisy fan and it came on frequently, and at all hours of the day and night,, because of the fridge- but just a 200 watt power upgrade and the new one seems to be able to cope with the fridge, hardly ever needing to run its cooling fan. 

 

 

 

 

 

 

  

Edited by Tony1
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2 hours ago, Higgs said:

I think I would use a dedicated inverter, other than the main boat's inverter. What are the power requirements of the fridge - about 45watts. So, something along the lines of a 150w pure sine wave. ?? Mains under the counter fridge with coolbox, power usage of about 130 Kwh per year. Any advances on that approximation?

 

 

Don't you need to go up to something like a 1kw inverter to cope with the starting current of a compressor fridge?

eta: When I had a gas fridge, apart from the poorer performance and lack of freezing capacity, I found it quite gas hungry. After swapping for a 12 volt, gas consumption from cooking and a gas water heater went to 4-5 weeks per 13kg from 2 weeks with the fridge.

Edited by Ex Brummie
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13 minutes ago, Ex Brummie said:

Don't you need to go up to something like a 1kw inverter to cope with the starting current of a compressor fridge?

 

That is something I couldn't be too sure of. In my case, I'd first run it up on the main 3kw inverter and check the fridge's startup needs, to determine the size of the dedicated inverter needed. There should be information out there, but it isn't at my finger tips. I've seen the 12v hit 5Ah, and I think 50w at start up, before dropping down. It's been a while since I measured it, and the fridge is now shot anyway. 

 

 

Edited by Higgs
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You are correct that the surge of current needed to start a 240v fridge's compressor is much higher than the rated current. I tried a 350w Victron inverter and that wasn't man enough. I found that the 'smallest' PSW inverter that I could get away with was an 800w Sterling unit.

 

The bigger the inverter the more quiescent energy it wastes when demand is low or zero, so unless your 3kw inverter is on 24 hours a day anyway, it may be worth having a dedicated inverter that is just big enough (800w) and even better, only have it power up when the fridge requires cooling.

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1 minute ago, Bargebuilder said:

You are correct that the surge of current needed to start a 240v fridge's compressor is much higher than the rated current. I tried a 350w Victron inverter and that wasn't man enough. I found that the 'smallest' PSW inverter that I could get away with was an 800w Sterling unit.

 

The bigger the inverter the more quiescent energy it wastes when demand is low or zero, so unless your 3kw inverter is on 24 hours a day anyway, it may be worth having a dedicated inverter that is just big enough (800w) and even better, only have it power up when the fridge requires cooling.

 

A 1000w would seem to be a better choice. Plenty of spare power. Never really good to run machines at their limit. 

 

 

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1 minute ago, Bargebuilder said:

You are correct that the surge of current needed to start a 240v fridge's compressor is much higher than the rated current. I tried a 350w Victron inverter and that wasn't man enough. I found that the 'smallest' PSW inverter that I could get away with was an 800w Sterling unit.

 

The bigger the inverter the more quiescent energy it wastes when demand is low or zero, so unless your 3kw inverter is on 24 hours a day anyway, it may be worth having a dedicated inverter that is just big enough (800w) and even better, only have it power up when the fridge requires cooling.

Dedicate an inverter to the fridge, it will need to be close to 1000w to ensure proper starting of the compressor. Wire the fridge thermostat to the inverter on/off switch so that the inverter is only on when the fridge needs it.  Works for me.

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24 minutes ago, Tony1 said:

 

Apologies in advance as I have limited experience, but these are a couple of the issues I recall being discussed: 

 

The guy below on youtube did a comparison test of 12v and 240v fridges, and with an inverter that is not too 'greedy' (i.e. doesnt draw too much current itself), the energy use is not vastly different. He determined that the presence or absence of a freezer compartment was a bigger factor in energy usage than the issue of 12c vs 240v. 

 

I also recall some folks mentioning that the standard of insulation on some 12v fridges was not great, and that 240v fridges with multiple energy star ratings are more energy efficient than a 12v fridge that is not well-insulated- perhaps the regulations for 12v fridges are less stringent in some way.

Perhaps a safe choice (if you do not have detailed knowledge about a particular 12v fridge and its insulation) would be a high-rated 240v fridge that has been converted to 12v, e.g. one of the LEC models.  

 

 

  

 

Almost all 12v fridges are just standard 240v fridges with the compressor changed for a 12volt unit. They are costly because the 12 compressor (which you can buy yourself) is expensive, and also the 240 volt compressor probably gets thrown away/sold on cheaply. If the insulation is poor that is only because the conversion companies choose to convert cheaper fridges to keep the cost down a bit. I think this is a false economy.

 

If you have a boat where you keep the inverter on full time then a mains fridge makes sense.

A figure that I have never seen is a comparison of the same fridge model in 240 and 12 volt configurations. I suspect the 12 volt is better but by how much??????

 

.............Dave

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17 minutes ago, dmr said:

 

Almost all 12v fridges are just standard 240v fridges with the compressor changed for a 12volt unit. They are costly because the 12 compressor (which you can buy yourself) is expensive, and also the 240 volt compressor probably gets thrown away/sold on cheaply. If the insulation is poor that is only because the conversion companies choose to convert cheaper fridges to keep the cost down a bit. I think this is a false economy.

 

If you have a boat where you keep the inverter on full time then a mains fridge makes sense.

A figure that I have never seen is a comparison of the same fridge model in 240 and 12 volt configurations. I suspect the 12 volt is better but by how much??????

 

.............Dave

 

Thanks Dave, the thing about poor insulation on some of the 12v models was something I saw reported elsewhere, I've not seen it myself.  Someone reported that they'd watched a 12v fridge get cut into, and the insulation was very little. 

I managed to find a cheap inverter that was 2kw but still only uses 0.5 amps when under no load, so I leave it on 24/7 for the sake of the fridge.

But if I abandon the fridge this winter, I'll start switching off the inverter at say 10pm, and save myself 10 hours at 0.5 amps... so maybe 5Ah saved.

 

https://www.amazon.co.uk/gp/product/B07DHKDTKB/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

 

I'm still pondering the idea of bodging together a heath-robinson setup, whereby I put a tube through the hull side with a very small fan on a timer, to suck in cold external air directly into the fridge for say 15 mins every hour.

From Oct to end of March, the external temp is generally cold enough to keep food decently well, and I could maybe turn off the fridge power supply for long periods- certainly overnight. 

The problem is there is a major risk that it just wont work very well, or will use almost as much power for the inlet fan as it would use for the compressor....  

 

 

Edited by Tony1
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