Fridge freezer knackered! Thetford N175

in h

Full Member

Messages
791
Firstly, if you choose a 3-way fridge, Domestic are far better than Thetford. Well worth the extra cost.

A compressor fridge is cheaper, requires less maintenance and is less likely to struggle in hot weather. But there are snags. Some are a bit noisy, but most aren't. Buyer beware.

The problem with compressor fridges is the power consumption and running cost.

Working on a typical 50Ah per day, this is easily manageable if you have covered your roof with solar panels, spend a bomb on controllers and have filed your lockers (and payload) with batteries.

But even so, in winter you will have a problem unless you drive for an hour or two every day.

The running cost of a three-way fridge on LPG is typically 300g per day, which costs 33p if you pay 55p/litre.

The running cost of a compressor fridge is in terms of battery cycle life.

50Ah is the entire usable capacity of a 100Ah lead acid battery. They typically cost about £100 and have a life of about 100 cycles. So that's £1 to run the fridge through a cloudy day. Yes, you'd need more than that one battery, but the cost works out pro rata: two batteries cost twice as much, last twice as long.

Assume instead that you have a 200Ah lithium battery costing £2000 with a service life of 2000 cycles. That's also £1 per cycle. So assuming your fridge is only using 33% of that battery's cycle life, it costs 33p per day: same as the LPG.

The essential difference is that any fool can fit a compressor fridge. Fitting a three way fridge needs care if it is to work in hot weather. And their electronics need a surge suppressor if you share hookup power with others.

Thetford fridges are very picky about being level within 3° (which is difficult) but Domestic are OK to 6° (which is at the limits of comfort anyway).

IF you already have 350+ watts of solar, 350+ Ah of battery bank, alternative charge source for cloudy weeks and everything working, consider a compressor fridge.

if you don't have all those, consider the cost and hassle of fitting them as well as the cost saving in the fridge.

It seems a lot of hassle for the one definite benefit: you can leave the fridge running when you go on a ferry.
 

David Cohen

Full Member

Messages
5
We are having to replace the Thetford N175 fridge freezer, in our 2009 Swift kontiki
Any suggestions, either, stay with Thetford or maybe change to Dometic, or anything else?
Thanks in advance
I would recomend Dometic products, switching to compressor units are more eficient but you need good batteries when of grid.
Earlier this year I changed to 2 100a Lithium batteries and found they are much better at holding a usable voltage which has kept my
12v Dometic compressor fridge,Webasto heating etc, working without any problems. In the long run I beleive this to be cheaper over time.
 

Ifor

Free Member

Messages
6
Just a suggestion, but phone Ian Walker on 07951 360260 for advice. He replaced the "cold bits" of my Dometic fridge for about 50% the cost of a new unit - he may be able to help.
 

wildebus

Full Member

Messages
3,568
The running cost of a three-way fridge on LPG is typically 300g per day, which costs 33p if you pay 55p/litre.
Where can I pay 55p/Litre for LPG? closest to me (which is not that close is 66p?Litres - so cost has increased 20%.

This also assumes a refillable system is in place. There are a lot (probably the majority) of 3-way fridge users that rely of bottle-swapping and not refilling tanks (the previous owner of my own Motorhome was in - and likely still is - in that category.
What does your 33/p a day change to when costing with Calor?


50Ah is the entire usable capacity of a 100Ah lead acid battery. They typically cost about £100 and have a life of about 100 cycles. So that's £1 to run the fridge through a cloudy day. Yes, you'd need more than that one battery, but the cost works out pro rata: two batteries cost twice as much, last twice as long.

Assume instead that you have a 200Ah lithium battery costing £2000 with a service life of 2000 cycles. That's also £1 per cycle. So assuming your fridge is only using 33% of that battery's cycle life, it costs 33p per day: same as the LPG.
Lead Acid - I think your "100 Cycles" would be pessimistic to the extreme. Even a basic wet cell Banner Bull battery is 200 Cycles and most are more.
Lithium - The price of a 100Ah Lithium Battery is more like £600 rather than £1000 nowadays - 200Ah would be £1,200, not £2,000

So with the cycle count of Lead adjusted more realistically; the cost of a Lithium Battery adjusted for current prices and the cost of LPG raised for current prices also, the COST of running a Compressor Fridge is comparable with the cost of running a 3-way on LPG. As the cost of batteries tends to drop and the cost of LPG tends to rise, the difference becomes smaller and smaller.
Once the complexity of a 3-Way (annual checks and service) over a Compressor (connect it up and that's it) ias taken into account, then Compressor Fridge will be cheaper to run.

The key difference IMO is that - assuming you can locate them - it is very fast to fill an LPG tank (or swap a Calor Gas bottle) compared to 'refilling' a battery, and that is why Compressor Fridges can be less attractive - or even an issue - in the Winter.

In Summer, much less so for anyone with solar - and with solar, that will likely put in much more energy than the Fridge will draw and the battery cycle count in the summer months will not factor into it, which makes the running cost of a Compressor Fridge even more attractive compared to a 3-Way.
 

nabsim

Full Member

Messages
2,510
Same as most things in life, it’s horses for courses. Yes undoubtably compressor fridges need adequate power storage and ability to replace power used. Lots of people only use their vans for holiday and odd weekends in good weather. By far the vast majority of motorhomes travel to a campsite the sit on ehu. If that’s the case then even a bu**ered 90ah battery would do the job.

Work out what you want and when you want to use it then look at the pros and cons of each type of device. For me it’s my 12v compressor, for you it may be 3 way. All good 😂👍
 

Ivanisafish

Full Member

Messages
5
maybe post a link to what you are referring to?
a "solar fridge" would only work in daylight I guess :) I am guessing it means as much as the term "solar generator" does :rolleyes:

12v Essentials Larder Fridge - Uses Only 10w Per Hour Average​

12v Essentials Larder Fridge - Uses only 10w per hour average

List Price: £405.98 +vat
£475 (inc vat) with 2.5% off for bank, card or cash payment

This is one I wad looking at. Assume they mean because it is low usage, you can run it off leisure battery, charged by solar?
 

wildebus

Full Member

Messages
3,568
That is pretty low power use :) you generally see around 1.3A average (so 15A ish) quoted for a fridge-type device (as opposed to a top-load box which are a bt better.
If you had a couple of hundred watts of solar, you could switch that on at Easter and it would stay running until the end of summer with no hookups. I had a Weaco 50L Compressor in my T5 with 200W on the roof and the batteries were full again by mid-morning every day.
 

SquirrellCook

Full Member

Messages
487

12v Essentials Larder Fridge - Uses Only 10w Per Hour Average​

12v Essentials Larder Fridge - Uses only 10w per hour average

List Price: £405.98 +vat
£475 (inc vat) with 2.5% off for bank, card or cash payment

This is one I wad looking at. Assume they mean because it is low usage, you can run it off leisure battery, charged by solar?
Some of them are just domestic fridges with an inverter in the back.
 

Exwindsurfer

Full Member

Messages
1,357
I’ve ran a 110ltr compressor fridge for over 8 years now and never ran out of battery power even when I was using
lead acid batteries I’ve 2 lithium batteries now + 400watts of solar .I can now remotely tilt my solar at angle angle so no prods in the winter .
 

nabsim

Full Member

Messages
2,510
Here’s a candidate for van fridge

 

wildebus

Full Member

Messages
3,568
Here’s a candidate for van fridge

That's a good price :)
Same size as the one in Clarence. more power (136KW/Annum vs 84KW/Annum) but about half the original price.

Your post reminds me .... Anyone want to buy a fridge? https://amzn.to/3w7Ju4T. Price from me - £109 :)
(I bought a backup one when it was on an offer but never needed it - and now Clarence is sold, I won't ever use it!)
 

in h

Full Member

Messages
791
Where can I pay 55p/Litre for LPG? closest to me (which is not that close is 66p?Litres - so cost has increased 20%.
Asda charges 52.7 per litre everywhere it stocks LPG. Morrisons charge about 56p, but vary the prices according to what they can get away with. Of course, if you don't live near one, and don't drive past one, that makes a difference.

Although some lead acid batteries will last a lot longer, a typical £100 100Ah battery has a usable cycle life of about 100 full cycles. Some last longer, but the reality is that many don't.

I'll take your word for the prices of lithium batteries.

As for annual inspection and service of 3-way fridges, all I can say is that in fifty years of using them, I've never yet paid for a single inspection or service. I do check and clean the vent each year, and clean the jet every two or three years. No cost, very little hassle.

On the other hand, I have to clean the channel round my car's hatch lid every month or two to stop fallen leaves blocking the drain pipes. Is that a reason to buy a saloon car? No, but it's still vastly more hassle than a 3-way fridge.

[Later]
Forgot to answer the question about refillable. Yes, it presupposes that you have refillable gas. If you don't, it's cheaper to fit than solar panels and lithium batteries. Just do it

I've no idea what LPG in bottles costs, but I'm sure it's vastly more expensive. Not a good approach for so many reasons, regardless of price differences.
 
Last edited:

Pudsey Bear

Full Member

Messages
1,729
What does "opens both ways" mean, I know you can change which way they open, but not seen one that opens both ways.
 

Users who viewed this discussion (Total:0)

Top