3-Way Fridge running on AC in a Motorhome - Power Consumption Test

[wildebus]

I created a topic around 3 years ago regarding running an normal domestic 240V AC Fridge in a Campervan (see AC Fridge In Campervan - Power Consumption Test to view)

I have since bought a motorhome that is fitted with a 3-way (12V, 240V and Gas) Fridge and want to run this in the most economical way (off Solar-Recharged batteries). This thread revolves around attempting this task and how well it will work .
Will it be or will it be ? Read on to find out!

Preamble

The Motorhome fridge is a typical 3-way Fridge that are fitted into Motorhomes. Mine is a Thetford unit with a freezer compartment and is fitted with an electronic controller that detects which energy sources are available and switches to them based on a pre-determined priority, based on expected energy costs (rather then efficiency).

1. Highest priority is 12V DC - Available when the engine is running (so the 12V power is regarded as a free byproduct of driving the vehicle)
2. Second priority is 240V AC - Assumed to be used when at a campsite with mains EHU (where usually a fee is paid for hookup/day and not based on usage)
3. Lowest Priority is Gas - Used when either electrical source is not available, but always costs money all the time the fridge is running.

As 12V is 'free', we will use that when available (bearing in mind 12V DC on a 3-way fridge is not that good and will not cool a fridge down, just maintain the temp - you need Gas or AC to cool). But the task is to try and eliminate the use of Gas even when not hooked up and no EHU available!


The Campervan fridge was a highly efficient A++ Energy rated Compressor Fridge that would draw around 40W when running, and had a duty cycle (time on vs time off) of around 20%. There are much more details about this in the other thread, but basically I could run that fridge non-stop in the campervan without the need to recharge from anything but Solar.
Doing an initial test of the Motorhome fridge on AC, it is rather a different picture. It draws 200W when running and has a duty cycle more like 66% (on twice as long as it is off). That adds up to a power consumption around 7 times greater than the Compressor Fridge! So is it feasible? Will it just kill the batteries and/or not leave room for anything else to work?


The Setup

The Motorhome is equipped with 300Ah of Lead Carbon AGM Batteries, a Roof mounted Solar Array of 270W connected via a Victron 100/20 MPPT Controller and a Victron EasyPlus 1600, of which a core element is a 1300W Pure Sine Wave Inverter.
The weather was fairly good with intermittant cloud so a reasonable day for solar harvesting (End of April and 55.6 Deg North if you want to look up expected irradiation/m3 )
I enabled the fridges AES (Automatic Energy Selection) mode at 10:00 to switch it from GAS to auto-detect (and so it selected AC immediately) and sat back to watch what happened.

The battery SoC (State of Charge) at 10:00 was 93.6%. The fridge actually started up at 10:20 (it must have just finished a cooling cycle) and starting drawing power from the inverter.

This graph shows how the fridge cycled on and off during the day (This Thetford is actually quite an advanced fridge of its type I believe. Some fridges are just always on).

3-Way - AC Daytime by David, on Flickr
In this view I purposefully selected an 6 hour window in the daytime so you can also see what is happening to the battery during this time period when the solar is active and the fridge is going on and off...

You see when the fridge is on, there is a current draw of upto 15A shown - and when the fridge is off, there is a current in of up to 10-12A - the numbers vary as the solar harvesting varies, but the end average effect of running the Fridge on AC off the batteries during this time is best shown in the Battery SoC graph below.

3-Way - SOC Daytime by David, on Flickr
In the time period selected, the Batteries charge level went from 93.7% down to 90.8% - so under 3% battery draw to run the fridge for 6 hours.
That's not bad. And actually, it could well have been 0% or the battery still gaining charge if the solar has been more efficient.

The maximum harvesting from the 270W array I was seeing was around the 200W max (it actually peaked at 199W) so whilst we never met the demand the fridge had totally from solar, it came fairly close at times and in the fridges "Off time", could make it up to a degree.

This graphic shows the 200W load from the fridge, with 190W coming in from the Solar Array.

3-Way - Dashboard Daytime by David, on Flickr
Together with the inverter overhead and other general DC demands, we have a shortfall of 43W that the battery has to make up. With a bigger array, that would happen. If I had connected up my 100W portable solar panel to work alongside the 270W array, we would have been in 'credit' even when the fridge was on at some times.

Conclusion so far: Running a 3-way Fridge on Batteries seems good


But what about when darkness falls?

Same graph as before, but the 6 hours until midnight

3-Way - AC Night by David, on Flickr
The AC Power looks pretty much as before, but check out the current and voltage graph ... With no charging going on (except a bit before 8PM), The current is all take out and nothing going back in of course, and the voltage is on the decline (being Lead based batteries, the voltage drops as the battery depletes).
This graph of the solar confirms the charging aspect

3-Way - PV Night by David, on Flickr

So if we show the Battery SoC for the last 6 hours of the day of fridge AC use to compare to the first 6 hours of fridge AC use, there is a dramatic difference

3-Way - SOC Night by David, on Flickr

With my 300Ah Battery Bank, I am seeing the fridge take out around 5% per hour from the battery. That is really too much to be able to run the fridge on AC overnight. But compare that to the daytime - when I lost only 3% over 6 hours - 0.5%/Hour on average.

Conclusion so far: Running a 3-way Fridge on Batteries seems good when the sun is out


This is a test that I have been meaning to try out for quite a while but had to wait until I got round to installing the Solar Panels on the roof.
It does confirm as a real-world test what I had previously calculated - that being that as a matter of course, running an electrically-inefficient 3-way fridge of batteries is really only viable when you have a way to recharge those batteries at the same time. I have a fairly large battery bank of 300Ah, of which I could draw 250Ah without any issues. If I had, say, a pair of 100Ah Lithium batteries it would not provide any greater running time. If you had a bank of half the capacity, you could still run the fridge during the day off them, but the Battery SoC would fall far more dramatically once the solar started to drop away.


The approach I took to try and get the best result (which is to get the lowest gas use) within the limitations of battery power and fridge performance was to have a setup that allows the fridge to see 240V AC available when appropriate (battery at a good State of Charge) and then when the battery starts to drop to a certain point, the fridge will automatically switch to Gas.
I have done this by using a device called an SSR (Solid State Relay) that either enables or disables the passing-through of AC Power depending on if there is a DC level signal present to turn the relay on or not. And that DC signal is supplied by another relay that goes on and off depending on the batteries State of Charge.
In my case I am using a Victron Cerbo to control the relay and in the test I carried out, I used the following parameters

SOC Control Settings by David, on Flickr
The AC would be available until the Battery SOC was lower than 65% and then would shut off. And then the battery would have to recover to 80% SOC until it would come back again. (PS. the screenshot shows Start below 65%, not Stop - that is just a quirk of how the routine I am using works - it is as I described it. A alternate device such as a Victron BMV would look different)

You want a decent gap between the two as you probably don't want to have the fridge flip-flopping between AC and Gas all the time. The numbers chosen could be different for different setups and circumstances. If you were getting great solar harvesting due to array size and/or location, you might decide to run down to a lower SoC. or if you are touring each day and have a good B2B to recharge whilst driving, the same could apply.
In the test carried out, the battery actually dropped to 65% SoC shortly before midnight and the AC Power to the fridge was automatically cut off by the SSR

3-Way - SOC65 by David, on Flickr

Controlling the Fridge power with automation such as an SOC controlled relay and SSR does to a large degree also assume you have a 3-Way Fridge with AES. If you have a unit where you need to manually chose the power source, then cutting the AC power once the battery drops to a certain SoC will just stop the fridge cooling until you switched from AC to Gas. The principle still holds good however and it would be a matter of remembering to switch the fridge from AC to Gas at a certain time - in my case without AES, maybe it would be switching it to Gas before I went to bed, and back to AC mid-morning, that kind of thing. You could with a Victron BMV set an alarm to buzz once the SoC dropped and that would be your reminder to switch over?


Final Conclusion: Definately worth using the 3-way Fridge on Batteries when appropriate and on Gas when not to cut the gas bill!

 

[xsilvergs]

You want a decent gap between the two as you probably don't want to have the fridge flip-flopping between AC and Gas all the time. The numbers chosen could be different for different setups and circumstances. If you were getting great solar harvesting due to array size and/or location, you might decide to run down to a lower SoC. or if you are touring each day and have a good B2B to recharge whilst driving, the same could apply.
In the test carried out, the battery actually dropped to 65% SoC shortly before midnight and the AC Power to the fridge was automatically cut off by the SSR

Nice detailed explanation.

At the moment my inverter switches OFF at a 75% SoC and switches back ON at 76% SoC. I am trying to get the gap (1%) as small as possible to use as much battery as possible. With so much sun, the fast charging of lithiums and 450 watts of solar panel things are working OK at the moment. The batteries are two 110Ah Ecotree type.

Question. Should your Thetford fail and be beyond economic repair, would you 'A' buy another Thetford, or 'B' replace it with a domestic 230V fridge/freezer?

 

[wildebus]

Nice detailed explanation.

At the moment my inverter switches OFF at a 75% SoC and switches back ON at 76% SoC. I am trying to get the gap (1%) as small as possible to use as much battery as possible. With so much sun, the fast charging of lithiums and 450 watts of solar panel things are working OK at the moment. The batteries are two 110Ah Ecotree type.

Question. Should your Thetford fail and be beyond economic repair, would you 'A' buy another Thetford, or 'B' replace it with a domestic 230V fridge/freezer?

What you have found with your Lithiums recharging faster is for sure a big benefit over Lead Batteries. Running the fridge it wouldn't make much difference during the ON cycle, but on the OFF it will and you may be able to recover faster.

Something I haven't checked yet ...
The Victron MPPTs have by default an 'Adaptive' Absorption duration, whereby you set your maximum time you want the controller to be in Absorption mode that day (batteries have a recommended time duration they like to sit at maximum charge voltage) and the default is 6 hour. The adaptive part is that depending on the voltage the battery is at when the controller wakes up in the morning will determine how long that absorption duration is. If the battery voltage is low, you get the full time, if it is higher, you get 1/3rd (I think) and if it is high, you get just 1/6th the time.
Yesterday because my starting voltage was pretty high, my MPPT controller would only give me 1 hour (1/6 of the 6 hour default) of Absorption until it switched into Float. And then after each bulk mode (when the fridge was on), it skipped Absorption

3-Way - MPPT Mode by David, on Flickr
Because this was the first time I really used the electrics extensively after fitting the panels I hadn't noticed the settings were at the default and I was loosing out on some harvesting. Noticed odd drops in the voltage when I looked at the info around 1 o'clock and when I looked at the settings saw it was still on the default 'adaptive' setting. Changed to 'fixed' and you will see from the graph above the controller never went to Float again that day, just to Absorption.
The bit I haven't checked .... Does this 'adaptive' setting apply when you have a Li-on setting on the MPPT Controller? I suspect not as the voltage of lithium is such you would always end up at 1/6th the number - and you tend to stay at bulk anyway with lithium - but could be worth checking?


If the 3-Way failed and I couldn't repair it pretty cheaply (so maybe spending less than what might be determined as 'economic' normally) I would go Electric Compressor, and almost certainly domestic 240V AC. You could get a very very nice 240V fridge for a lot less than the price of a 3-way Motorhome jobby.

 

[wildebus]

Question. Should your Thetford fail and be beyond economic repair, would you 'A' buy another Thetford, or 'B' replace it with a domestic 230V fridge/freezer?

This is a potentially useful PDF that shows what new Thetford Fridge is a match - at least in terms of Dimensions - to an older fridge.

https://www.jacksonsleisure.com/content/pdf/thetford/Thetford-Refrigerator-Conversion-Overview.pdf

It kind of assumes a like for like replacement in terms of energy sources, but if you compare just against sizes, you can find all-electric models that are a like-size for a 3-way absorption fridge.
For example, in my own case if I wanted a Thetford Compressor replacement for the current fridge, it would likely be (depth a few mm more though) the Thetford T2175, which looks like a very nice unit and would definately (IMO) be a better buy than the Absorption equivalent.
Still an expensive option there compared to a domestic AC fridge, so if one available to suit the hole (1246 x 525 x 606) that would be the more cost effective solution.
A quick look on Amazon shows quite a few options. For example this LEC AC fridge is just £255 - https://amzn.to/3vpmgpZ
It is 20mm short and 25mm narrower so would fit in pretty easily with some bracing on the sides to secure and a custom-made front bezel to make it look integrated - the cost saving of nearly £1,000 over the Thetford 12V Compressor Fridge/Freeze would pay for quite a bit of shopping to fill her up


Something to bear in mind for anyone who decided they want to swap out a 3-way for a 12V Compressor Fridge ... the 12V wiring to the fridge would have to be worked on. The 12V supply from the leisure battery only supplies power to the light and electronics board and will be inadequate to run the compressor. An AC mains compressor fridge should be fine though as the AC cabling to it should handle the current required (but you should still confirm for yourself of course. Whilst the running power is lower, Compressor Fridges have a high but very short duration in-rush current on each compressor startup, and that current is much more than an absorption fridge will demand).

 

[Nabsim]

Questions Dave, because Lifepo4 would maintain a higher voltage throughout the time you had no solar harvesting would it actually use less power than your lead carbon? I know higher voltage systems are more efficient but not sure if 1v is negligible if I have explained well enough.
Would a good test not be to drop to 12v at a certain SOC rather than going to gas? I know a lot of people with compressor fridges apparently turn them off at night (not adequate system?) and dropping to 12v would maintain temperature.
Being in the van a lot of the time I see a problem in taking out without being able to charge as you can easily get two wet days together in summer with little harvesting. May need some fancy programming then to swap between 12v and 240v for maximum efficiency from the battery bank. In reality you would just limit using 240v to high SOC but I was thinking of people using their 3–way without gas at all.

 

[wildebus]

Hi Neil,
Lithium would be slightly more efficient as a higher voltage would mean less current, but talking a couple of percent. Variances in solar harvesting would make much more impact.
If it was a 3-way, dropping to 12V would be tricky as that is supplied by the vehicle battery and only then when engine is running. You would need to rework the electrics for one thing and the 12V is maybe the least efficient - it would be a constant drain like a basic coolbox and kill the starter battery by the morning.
And yup - turning off compressor fridges overnight is common amongst campervan folk with undersized batteries because they get sold a myth of how they just tickle a battery and run on fairy dust electric.
I don't believe it is possible to genuinely run a 3-way fridge off batteries 100%. They are just too inefficient. When I was looking last night at alternatives that fitted, I was also seeing the power consumptions quoted of a 3-way ... 4kWh/day! That is massive! A 100Ah lithium battery will give you 1300Wh. So you would need 3 lithiums to run just a 3-way for a day with no charging. That is not viable. The only way to use a 3-way without gas would be pack it with insulation and turn it off overnight. My own objective is to be able to use something "normally" (so don't hold with the turning compressor fridges off overnight either. Dangerous practice when it comes to food, especially in a freezer compartment )
I guess the backup plan if poor solar would be (assuming no generator) to run the engine for a short time. Remember a compressor fridge is much more efficient and if you ran the engine for say 30 minutes, that will put into the batteries a days worth of fridge power.

Ignoring the electrical inefficiency, I like my fridge and I do also like the fact I have the options of alternative sources of energy so not swapping it out in the near future, but 3-ways are a dinosaur of a product, especially with how common solar is and the way lithium allows more battery power in a limited space.

 

[wildebus]

Going to review my fridge power usage again today, as the weather has turned significantly, and is cooler as well as raining and cloudy so solar will be much poorer. I also turned the temperature setting up as it was set fairly low. So we could have quite a different scenario today
I plugged into hookup yesterday to fully charge the batteries and get the SoC right back to 100% (aside comment: the State of Charge Monitors like the BMV need occasional resyncing - mine I suspect was around 5% low looking at the data).

A bit oddly, the fridge went off around 23:30 last night and has not come back on
I actually went into the van this morning to check it has not reverted to Gas or something but no, it is still on "Auto" and showing AC as the power source, and I checked the inside with a thermometer and it is around 2C in the fridge and -2 in the freezer (maybe that is a touch too high?). So just a combination of cooler weather and a lower setting has made a seemingly massive difference to the energy usage. Just shows how hard it is to have consistant comparisions - but as I have said previously on the other tests on the compressor fridge, this is not a lab environment, just someone doing some testing and sharing their results

As of now (10:30) the batteries are still at full power (EHU is disconnected); The Solar is providing all the electrical demands currently and the fridge has not drawn any power for 11 hours(!)

I'm hoping the fridge will kick in soon as I want to see it still works!

 

[mb2tv]

This is all very interesting for me, as I am looking at the options. I am just at the start of looking into it, and the current thought is to make the jump and buy a 12v compressor fridge. Thetford does not come 'high' in reviews, so not considered. New MH come mostly with a 12V compressor and not an absorption one.
My worry with your setup Dave, is that you rely on an inverter - for me that is another 'component' that can fail, so might consider a separate inverter (lower power) just for the fridge. That way, you have the backup of the big inverter. Then I looked at prices: if you go for a quality fridge (there plenty of cheap ones, rating varies) and calculate the additional inverter, the difference between the two options is smaller.
I also need to consider that my daughter will also use the MH, so fiddling is not an option.
The two brands that I have seen use are Dometic and Vitifrigo.

 

[wildebus]

This is all very interesting for me, as I am looking at the options. I am just at the start of looking into it, and the current thought is to make the jump and buy a 12v compressor fridge. Thetford does not come 'high' in reviews, so not considered. New MH come mostly with a 12V compressor and not an absorption one.
My worry with your setup Dave, is that you rely on an inverter - for me that is another 'component' that can fail, so might consider a separate inverter (lower power) just for the fridge. That way, you have the backup of the big inverter. Then I looked at prices: if you go for a quality fridge (there plenty of cheap ones, rating varies) and calculate the additional inverter, the difference between the two options is smaller.
I also need to consider that my daughter will also use the MH, so fiddling is not an option.
The two brands that I have seen use are Dometic and Vitifrigo.

The inverter is a potential failure point - and one that can be eliminated by a 12V Compressor Fridge. However, look at the flip side .... a 12V Compressor Fridge is around 4 times the price of a 240V Compressor Fridge. you can get a lot of inverter for that money saving or even carry a spare!
A lot of this has been discussed in the other thread about using an domestic AC fridge in a Campervan - might be worth having a look at that to see some of the points raised? But to recap the basic points:
I use an inverter anyway, so there is no additional cost for it; A fridge is on 24/7 so you need an inverter that is designed for that kind of usage (when it comes to leisure electrics, Inverters are maybe the most variable in quality and it really is a matter of getting what you pay for); A 240V Compressor fridge has a high start up current - so even though you only need a tiny inverter when running, you need an inverter that can deal with 900W surges. So basically if you are an inverter user anyway, just get a decent one and use it for the fridge as well

Is using an inverter really a worry? In my Camper I have a 240V fridge that cost £170. The 12V option from Weaco would have been around £700+ and actually less efficient. Until a few months ago it was running 24/7 for a couple of years and the only reason it is not now is there is no reason to leave it on. Got no concerns at all with the fridge working and the Inverter running it.
Fiddling to work it? having a fridge that looks just like your fridge at home can't get much easier? the Inverter is just left on and runs it. What fiddling is there to deal with really?
Another thing to consider .... replacement costs. If that was a Dometic 12V fridge or Waeco and it went wrong (just 1 or 2 years warranty), it would be another £700+ to replace and have to source. A domestic fridge can be found in thousands of stores across the UK and Europe for a fraction of the price. I actually have a spare fridge in my Shed the same as the one fitted - paid £85 in a Prime Deal on Amazon, so if the fridge DID go wrong, it would be very little to replace compared to the 12V options

My Fridge is a Thetford so I am just comparing like for like for ease as the sizes all match. Not done any quality comparisions myself as I am not looking or hoping to buy anything at the moment

 

[mb2tv]

I did read the other discussion - I am still sitting on the fence, that is why the questions. Thank you for the info and rhe patients !

 

[Nabsim]

My fridge is a 110ltr Waeco 12v only and I run it constantly. I have noticed over the last couple of weeks I am using less power overnight Dave. Not massive amounts but maybe 5% more on SOC when I get up. This surely has to be less interior/exterior lights and less diesel heater though?
Looking forward to see what today brings, will make up for a bad weather day for you if nothing else (he says as the sun pops out)

 

[wildebus]

The fridge has still not come on at all! I am going to have to go out and check the internal temp and that it is still set for AC (probably lower the temp setting as well just to make it come on!)

still cold (ish. think setting a little high). turned it off and on and still selected AC automatically as it should. lowered temp a click or so and started up

 

[SquirrellCook]

This is all very interesting for me, as I am looking at the options. I am just at the start of looking into it, and the current thought is to make the jump and buy a 12v compressor fridge. Thetford does not come 'high' in reviews, so not considered. New MH come mostly with a 12V compressor and not an absorption one.
My worry with your setup Dave, is that you rely on an inverter - for me that is another 'component' that can fail, so might consider a separate inverter (lower power) just for the fridge. That way, you have the backup of the big inverter. Then I looked at prices: if you go for a quality fridge (there plenty of cheap ones, rating varies) and calculate the additional inverter, the difference between the two options is smaller.
I also need to consider that my daughter will also use the MH, so fiddling is not an option.
The two brands that I have seen use are Dometic and Vitifrigo.

In the Murky build I have two inverters, one running from the engine start batteries and the other from the habitation. When driving at night, by moving a three pin plug I can swap mains circuits to run from the engine inverter. This enables me to run the mains fridge, charge the habitation batteries and any other thing like phone/pad chargers. The plug and socket just interrupt the EHU feed. Very easy to do.

 

[wildebus]

In the Murky build I have two inverters, one running from the engine start batteries and the other from the habitation. When driving at night, by moving a three pin plug I can swap mains circuits to run from the engine inverter. This enables me to run the mains fridge, charge the habitation batteries and any other thing like phone/pad chargers. The plug and socket just interrupt the EHU feed. Very easy to do.

Am I right in thinking the one on the engine battery is a 24V input and the one on the habitation battery is a 12V input?

 

[wildebus]

The fridge has still not come on at all! I am going to have to go out and check the internal temp and that it is still set for AC (probably lower the temp setting as well just to make it come on!)

still cold (ish. think setting a little high). turned it off and on and still selected AC automatically as it should. lowered temp a click or so and started up

View attachment 3782

Since adjusting the temp setting a bit low it hasn't gone off! I think it was a little too high before as the freezer was only just below freezing. might be quite senstive to the settings? will need to keep an eye on this. I'll be putting a temp sensor inside the fridge and connecting that to the Cerbo once I work out the best routing for it so will be able to easily see what is going on.

Also lowered the SOC cutoff down to 40% (which would mean approx 12 hours of fridge running time with a typical on/off pattern - the actual time will depend on duty cycle) as I am interested just how long it will run in what seems to be a initial cooldown process, even though must have been very close to start with?
(just looked at VRM and just this minute the Inverter switched to Low Power)

 

[SquirrellCook]

Am I right in thinking the one on the engine battery is a 24V input and the one on the habitation battery is a 12V input?

Yes you are correct, Mercedes bit 24 volt. Amateur bit 12 volts.

 

[Sprinter 1 cup]

Fill fridge up with any thing as that will store engery too.

 

[xsilvergs]

Today at 51.33792° N, @ 15:43 my 450W of solar is producing ~335W which is running the inverter for the fridge, supplying the parasites and putting 2A into the battery. SoC now 99.3%. Not bad. Drove down from Hereford this morning so battery was at 99% when we arrived.

I have set the fridge switching threshold back to 90% but plan to use solar charger state (On Off), SoC and time to adjust the threshold on the fly.

 

[Traveller]

Nice article, I have been thinking of doing this also with my setup. To use this system without an inverter I plan to do the following.
My fridge is wired up to the house batteries directly. There must be a wire from the ignition circult to tell the fridge that alternator is running to tell it to draw power from the 12v house batteries. I could place a diode in this circuit. Add a switch with another diode from the heavy 12v wire form the house battery. So if either the alternator is running or the switch is on the fridge will run off 12v.
Circuit: (existing Ignition) --|>|-- (connection on fridge where existing ign. connection went to) --|<|-- (manual switch) -- (heavy 12v wire from house batteries).
Additionally if I want to make it automatic install a BM712 and use the relay output in series with the new switch to turn on at 95% and off at 80%.

 

[MatijaSever]

Nice detailed explanation.

At the moment my inverter switches OFF at a 75% SoC and switches back ON at 76% SoC. I am trying to get the gap (1%) as small as possible to use as much battery as possible. https://eldfall-chronicles.com/product/single-model-thenrin-swashbuckler/ With so much sun, the fast charging of lithiums and 450 watts of solar panel things are working OK at the moment. The batteries are two 110Ah Ecotree type.tojiro knives

Question. Should your Thetford fail and be beyond economic repair, would you 'A' buy another Thetford, or 'B' replace it with a domestic 230V fridge/freezer?

I'm glad you found the explanation helpful!

Regarding your question, it depends on your preferences and requirements. If you are satisfied with the Thetford fridge/freezer and it meets your needs, you might consider buying another Thetford.