Thetford Fridge

[alcam]

My experience is going the other way .... after a compressor coolbox and 2 compressor fridges in my 3 self-builds, when I bought a "proper" Motorhome, it came with a very nice Thetford 3-Way Fridge/Freezer.
It was nice not using any battery power (the MH had a pair of knackered batteries when I bought it) but not so long afterwards, it wouldn't light reliabily or cool as well as I wanted. Messed around with the burner and the thermocouple and got it working again for a while, but then started playing up again. Had enough and just took it out and fitted a Compressor Fridge.
the BRAND NEW Compressor Fridge-Freezer cost the same as I got for the 14 year-old Thetford 3-way fridge on eBay. With a 3-way fridge, you have burners to clean, flues to clear, vents to close off in winter and open in summer,etc. With a compressor fridge, servicing is plugging it in when you fit it and .... that's it!
I can't recall anyone who switched to a compressor fridge and used it for more than a year and then wished they had a 3-way instead.

Yea honestly not doubting the technical evidence . Stastically speaking though you had 1 bad experience with a 3 way , I've had 4 good experiences !
Maintenance ! What is this of which you speak ?
Current fridge almost 6 years old has spent 90% of its life on gas . Never run out of gas . Burners , flues , vents never touched them .
Almost certainly going to be the proud owner of a compressor fridge quite soon .
Good to know I can continue with my maintenance regime !

 

[trevskoda]

This time of year it would do better hanging vertically on the side of the van

Or in winsheld and point van at sun, thats my next job with a small 30w panel i have, going to make one cigy socket a direct feed to regulator input.

 

[alcam]

As I said simple , short term , solution would be just to double up leisure battery.
Have messaged various companies for estimate on complete new installation. Solar , lithium and all associated equipment.
One back so far , £1800 . From what I've read on here doesn't seem too bad .
Will get under mattress and see what is left !

3 estimates so far . Obviously full details not finalised yet but highest estimate just short of £4k

 

[Robmac]

3 estimates so far . Obviously full details not finalised yet but highest estimate just short of £4k

It will vary on what gear they use (obviously!). Victron is widely reported to be the best and it's what I've gone for along with Fogstar Lithium. Cables and Crimps, Shunts, Busbars, Mega Fuses etc etc. all add up to a pretty Penny as well.

Having said that many people have gone with cheaper gear and are more than happy with it. I would ask for a breakdown of the costs if I were you and see what they are charging for labour, also it may well be that you can get the various boxes etc. cheaper yourself and just pay for the install if you don't fancy doing it yourself.

(not wishing to teach granny to suck eggs of course!)

 

[Robmac]

...there are various kits such as this available as well;

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine

12V solar panel solar charging kits for motorhome caravan boat campervan yacht marine off-grid

www.photonicuniverse.com

Ecoworthy do various size kits as well.

 

[wildebus]

3 estimates so far . Obviously full details not finalised yet but highest estimate just short of £4k

but again ... what are you getting for the £4k? and are the quotes for the £1800 and the £4000 for the same size battery, same amount of solar, etc? (even ignoring what kit is being talked about).
£4k is not neccessarily enough for a signicant quality upgrade.

 

[alcam]

It will vary on what gear they use (obviously!). Victron is widely reported to be the best and it's what I've gone for along with Fogstar Lithium. Cables and Crimps, Shunts, Busbars, Mega Fuses etc etc. all add up to a pretty Penny as well.

Having said that many people have gone with cheaper gear and are more than happy with it. I would ask for a breakdown of the costs if I were you and see what they are charging for labour, also it may well be that you can get the various boxes etc. cheaper yourself and just pay for the install if you don't fancy doing it yourself.

(not wishing to teach granny to suck eggs of course!)

You're not Rob . All advice is welcome . Certainly won't be a diy job .
Spent many years running cables , wiring equipment etc . Even a little in vehicles.
Not doing it again

but again ... what are you getting for the £4k? and are the quotes for the £1800 and the £4000 for the same size battery, same amount of solar, etc? (even ignoring what kit is being talked about).
£4k is not neccessarily enough for a signicant quality upgrade.

Obviously would need to finalise all of that .
£4k way above what I'd be spending.
Appreciate this will require some compromises .
Would be happy with reasonable (again, not exactly scientific) increase in power .
Only difference on current usage of power will be the fridge .
Think decent batteries , compatible charger etc , maybe another solar

 

[wildebus]

You're not Rob . All advice is welcome . Certainly won't be a diy job .
Spent many years running cables , wiring equipment etc . Even a little in vehicles.
Not doing it again

Obviously would need to finalise all of that .
£4k way above what I'd be spending.
Appreciate this will require some compromises .
Would be happy with reasonable (again, not exactly scientific) increase in power .
Only difference on current usage of power will be the fridge .
Think decent batteries , compatible charger etc , maybe another solar

This is what I would suggest to someone who wanted to be able to spend more time off-grid but also wanted to to spend as little as possible - within reason. And is on the assumption that the vehicle they are updating is a keeper for the freseeable future - say 4+ years....

B2B Charger - worth installing for sure. I would go for Ablemail or Victron 30A units (Ablemail top quality but a little pricey. Victron good but tends to run a bit hot) at around £200+ . Or a Victron 50A Orion-XS B2B at around £300+. Depending on base vehicle you may or may not need a fresh cable run. Proper UK/EU pure copper cable is NOT CHEAP. Prepare to pay. Far East cable is pants. avoid.
Solar Controller - MPPT needed. And whatever size to match panels. Victron SmartSolar MPPT range now very good value. I wouldn't use anything else currently.
Mains Charger - if mostly off-grid, maybe stick with what is fitted if reasonable, or get a 20A or 30A unit. Watch out for the ebay bargain ones. They may well work, but usually so noisy they are not suitable for a camper. (I've replaced respectable working mains chargers for silent Victron ones for customers).
If considering an Inverter, think of a Victron Multiplus- good value compared to a separate Mains Charger (AC-DC) and Inverter (DC-AC) as same things in reverse and Victron use that fact to combine components and save costs.

Solar Panels - if Glass framed, just about any is fine. Get them to suit the space on the roof (I happened to get Victron on mine not because they were Victron, but the shape of their panels just happened to be just what I needed. Used EcoWorthy previously and been perfect as well). Yes, there are nuances to different glass panels but that only comes into play when at the upper end of upgrades I would say.
If semi-flexible, watch out for 'bargains'. Only semi-flexibles I would fit are from Photonic Universe - not cheap!
If I was doing an install and someone gave me no-name semi-flexible panels to fit, I would decline as they will likely fail prematurely - and it will of course be the installers fault as far as the supplier is concerned.

Battery - depends what space you have. Lithium has become much more of a commodity now as prices have fallen, but those falling prices means the quality players such as BMS Tech, Battery Megastore and Alpha Batteries have had to drop prices to compete. I would spend the bit extra and get a battery from a vendor I know & trusted and has been around for a while, such as those three, rather than from an Amazon or eBay listing.

 

[molly 2]

My 3 way thetford died while in warrenty , it lost its gas so scrap .wot a waste .

 

[Chasn]

The one regret with my 2018 Carthago that it has a good sized 3 way fridge rather than a compressor fridge. The size is great but when I run it on my inverter it takes 15A. Fortunately I have 600Ah lithium battery. Even if I could find a compressor fridge that fits the narrower 400mm aperture I am not inclined to rip out the existing one until I have to. One question. Is it any more efficient to run a 3 way fridge on 12v DC rather than 240v AC? My inverter uses about 1A on standby so even if the energy used at the fridge was the same there might be a small saving there.

 

[alcam]

The one regret with my 2018 Carthago that it has a good sized 3 way fridge rather than a compressor fridge. The size is great but when I run it on my inverter it takes 15A. Fortunately I have 600Ah lithium battery. Even if I could find a compressor fridge that fits the narrower 400mm aperture I am not inclined to rip out the existing one until I have to. One question. Is it any more efficient to run a 3 way fridge on 12v DC rather than 240v AC? My inverter uses about 1A on standby so even if the energy used at the fridge was the same there might be a small saving there.

Don't you run it on gas ?

 

[wildebus]

The one regret with my 2018 Carthago that it has a good sized 3 way fridge rather than a compressor fridge. The size is great but when I run it on my inverter it takes 15A. Fortunately I have 600Ah lithium battery. Even if I could find a compressor fridge that fits the narrower 400mm aperture I am not inclined to rip out the existing one until I have to.

It is easy to find a 400mm compressor fridges if you want one.

One question. Is it any more efficient to run a 3 way fridge on 12v DC rather than 240v AC? My inverter uses about 1A on standby so even if the energy used at the fridge was the same there might be a small saving there.

As i understand it, on 12V it will attempt to maintain the existing temp; on AC it will actually cool to the setting.
This picture showing the cabling to the elements is likely typical of most 3-Ways and explains why one is more effective in terms of operation and one uses less power

Thetford 3-Way Electric Power by David, on Flickr

But one reason why running a 3-Way off battery power for an extended period is not feasible....
Couple of graphs comparing 3-Way Fridge running on 240V AC Electricity vs a 240V AC Compressor Fridge

3-Way

3-Way - AC Daytime by David, on Flickr

Compressor

240V Compressor Fridge by David, on Flickr
(The initial power spike lasts around 3 seconds)

When the 3-way is running, it uses much power and it is also one more often and for longer. In terms of power consumption, the 3-Way uses about 7 times more power than a compressor fridge

 

[merl]

One question. Is it any more efficient to run a 3 way fridge on 12v DC rather than 240v AC? My inverter uses about 1A on standby so even if the energy used at the fridge was the same there might be a small saving there.

I've not measured it but a watt is a watt no matter how it's sourced so I'd imagine that AT THE FRIDGE there's no difference.
In order to ascertain the OVERALL efficiency you need to take in many other factors and inefficiencies such as the 1A standing current consumed by the inverter that you mentioned but also an inverter is only about 90% efficient in its power conversation too so in total you'd be wasting quite a bit running on 12v rather than 240. How you've gained the 12v power from needs to be considered, via mains charging, alternator or solar because only solar is truly 'free'.
The 12v side is typically energised via a relay ONLY when the engine is running so if you wanted to run the fridge from 12v while stationary a certain amount of reconfiguring of the 12v wiring would be needed.
I'm actually in a similar situation as yourself, we have a 3way and in the summer I find I have a surplus of 12v solar and sometimes I use the inverter to power the fridge while stationary to save some gas but I know I could be a little more efficient IF I used 12v instead so I've thought about the idea but another consideration is control, I've heard it said that only the gas and 240v sides are thermostatically controlled and the 12v is permanently connected, if this is correct then this would really need attention too. Also the 12V element needs to be the same wattage as the 240, if it's significantly lower then the 12v side probably wouldn't 'keep up' during hot weather.
When the weather improves I plan to do a little more investigation into the subject, too cold at be the moment

 

[wildebus]

What you can also do if the inverter is dedicated to the Fridge is do a setup where when the fridge isn't demanding power, the inverter automatically goes off rather than being on Standby.
If you have a 240V AC Compressor Fridge, doing this can save a fair bit of power as the fridge is on only around 25-33% of the time. Less effective with a 3-way as they will be on for the majority of the time.

I just have mine going into low power/standby mode though as I use the Inverter for other things.