Thetford Fridge 3-Way on Gas

[wildebus]

Dometic say you can expect some temperature regulation on mains and gas but not 12v.
As I said earlier you can hear a thermostat click run-out when turning my old 'mechanical' fridge temp dial so presumably there would be some cycling.
The current on 12v is far too high to put through a thermostat and if I remember correctly the element wattage is lower so constant duty is used.
I can see how a capillary bulb could partially close the gas supply and reduce cooling effort.
On an electronically controlled fridge the gas could be turned off and relit I suppose.

I think mine just sets a constant flame dependent on the position of the temperature knob because after an extended time on gas I have to ease it off as the fridge gets too cold.

My Gas goes on and off as demand changes as mentioned. There is something to be said for a constant flame and no complicated electronics though!

For electric, a little photo of the back ...

so meant to be 200W at 220V - which is why I am drawing 215W as my voltage is not 220V but 237V
and is 147W at 12V - so around 12.5A (to Thetfords credit, the cable they use for the 12V supply is very chunky - think it is 6mm2)

 

[wildebus]

A great report - as ever A*
So for a 3 way the only mains electric supply you would want to us for any period of time would be unmetered - hard to come by nowadays!

Still thinking about keeping it?

This morning I woke up and I was wondering if my neighbour would give me a hand pushing it through the hab door (2-man job for sure!) and refitting it.
After doing the maths later on I am more doubtful as, as you say, I have the battery power to support a Compressor Fridge and I do like to leave the fridge on 24/7 - and on a 3-way that is pretty wasteful


But I am very pleased that the fridge would look to be A1 working condition again .
And for the grand total of £0.00 in parts as well, which is interesting considering the usual MO with fridges seems to be to throw parts at something until you run out of money or patience.
The chimney flue is clean (it is not even sooty); the little vane jobby is in there neatly and fully intact; all looks good if a bit rusty on the pipe surfaces.

 

[wildebus]

Right .... Decision made I think!

After looking on eBay and seeing how much used Thetford 3-Way fridges are selling for, my N180 is going up for sale!

 

[wildebus]

Thought I would post the 12V Update ....

So been running on 12V to simulate driving from around 10:00AM to just before 3:00PM today. A 5 hour drive is fairly long so this will be a good indiction of how well the 12V element is doing its job.

Again, temps for Fridge and Freezer sections. I'll show the entire timeline as that I think is quite typical ... turn the fridge on the afternoon before a trip, running on AC for initial cooldown overnight before setting off on a trip.

Fridge first

Temp increases slightly as 12V is not as good as Gas or AC in use, but still a very decent 3.9C after 5 hours on 12V and only a 1.7C rise from the very coldest.

Freezer now

Here we are actually getting a slight drop in temp, so the food will certainly stay frozen.

The ripple in the temp shows the power is cycling on 12V just as it does on AC
Slightly different duty cycle however - the ON duration is less than the OFF. This makes sense as the element is smaller so would need to stay on longer to get the same overall hourly output.

(The power output shown from around 09:00 includes some constant battery charging - I am running the fridge off a charger, but also connected to a battery to provide a bit of smoothing and bulk in case of any load spikes)

There was a question on what kind of control the fridge could have on the 12V side? The fridge will only switch to the 12V input (either in Auto mode or use in Manual mode) when the D+ signal is high, regardless of the presence of 12V on the load terminals. So there is a 12V relay inside the fridge controlled by the D+, and so also controlled by the electronics - which means the fridge can disable 12V based on cooling requirements just as easily as the other power sources

 

[ramblefrog]

I spoke to soon!! Just arrived back from a few days away running the fridge off gas. No problems until the last day when is started flashing with error code 11.
The manual says its a supply issue but I have 3/4 tank of LPG. It runs on battery, with the engine running and 230v on hook up but not gas.
So I am desperately ringing every place in Sussex I can find to get it fixed before next Thursday
I just dont have the confidence or skill to be poking around in the fridge workings.

lee2479@gmail.com
07732707909
The above gentleman fixed our 3 way fridge at short notice. He is in Peacehaven E.Sussex and registered motorhome habitation person.
He fixed a few things on our van which is a fairly old CI Fiat Ducato 2000.
Fridge worked on hook up and battery but was unreliable on gas. We did attempt to fix ourselves without success. He knew what the problem was and cleaned out pipes (rebored existing parts and cleaned). We are just back from Bath (in this heat) and the fridge worked perfectly on gas and we had ice - yeh.
I phoned on the Thursday and he said if we could go to him on the Friday afternoon he would take a look so we were grateful. He also fixed a few other niggles. We are going to book him for a habitation check - we are in West Sussex.
Good luck

 

[Jenrai]

lee2479@gmail.com
07732707909
The above gentleman fixed our 3 way fridge at short notice. He is in Peacehaven E.Sussex and registered motorhome habitation person.
He fixed a few things on our van which is a fairly old CI Fiat Ducato 2000.
Fridge worked on hook up and battery but was unreliable on gas. We did attempt to fix ourselves without success. He knew what the problem was and cleaned out pipes (rebored existing parts and cleaned). We are just back from Bath (in this heat) and the fridge worked perfectly on gas and we had ice - yeh.
I phoned on the Thursday and he said if we could go to him on the Friday afternoon he would take a look so we were grateful. He also fixed a few other niggles. We are going to book him for a habitation check - we are in West Sussex.
Good luck

Hello, thank you info. This is the same person that has come today to look at my faulty fridge. Everyone else was too busy. He is so helpful and once my new pcb arrives said he will swap it for me. Honestly I can't recommend this guy enough he is brilliant.

 

[ramblefrog]

Hello, thank you info. This is the same person that has come today to look at my faulty fridge. Everyone else was too busy. He is so helpful and once my new pcb arrives said he will swap it for me. Honestly I can't recommend this guy enough he is brilliant.

What a coincidence.
Great to hear you are nearer a resolution.

 

[wildebus]

Think you can see when the power was switched from the 3-way fridge to the compressor fridge

 

[xsilvergs]

Here is my Victron 500W Phoenix Inverter powering the Thetford N3170 yesterday, it did carry on for another hour until 1AM. A compressor fridge would be nice.


There are 2 110Ah Lithium batteries charged from 750W of solar panel.
Here is the SoC.

In this instance the inverter was switched off when the SoC dropped to 50%. Trying to get good solar predictions to determine a reliable and variable SoC cutoff isn't proving that easy.

Heating the water via the Truma is another idea for using the solar energy.

 

[Markd]

@wildebus
I've just ordered one of the thermometers you're recommending - I fear I'm in for a shock when I run my fridge.
I expect then I'll be wrestling it out and turning it over for a few days - at least I won't be stripping it down to get it out of the van
Did you agitate yours at all or just leave it dissolve the crystals or whatever it does?

 

[wildebus]

@wildebus
I've just ordered one of the thermometers you're recommending - I fear I'm in for a shock when I run my fridge.
I expect then I'll be wrestling it out and turning it over for a few days - at least I won't be stripping it down to get it out of the van
Did you agitate yours at all or just leave it dissolve the crystals or whatever it does?

I just turned it upside down and left it for a week. I guess it did have a fair bit of agitation taking the thing out the door!

 

[wildebus]

Here is my Victron 500W Phoenix Inverter powering the Thetford N3170 yesterday, it did carry on for another hour until 1AM. A compressor fridge would be nice.
View attachment 60462

There are 2 110Ah Lithium batteries charged from 750W of solar panel.
Here is the SoC.
View attachment 60463
In this instance the inverter was switched off when the SoC dropped to 50%. Trying to get good solar predictions to determine a reliable and variable SoC cutoff isn't proving that easy.

Heating the water via the Truma is another idea for using the solar energy.

I've tried using the "excess" solar for both water and 3-way fridge now....
It will depend on how much solar energy you are harvesting (weather and array size), but it say you like to leave the water heater on to give you on-demand hot water (not sure if people do that or just switch on the water for a planned 'event' like a shower or washing up?), I've found the hot water on electric will take care of any spare power the solar gives.
In the case of my Truma Ultrastore, it is on initially for around an hour and then on again every 90-12 minutes for 10 minutes to top up the heat. That is often a fair proportion of the solar harvesting (and of course a fair bit needed for battery recharge) - and of course if water used, that is another full water heat cycle probably?
With the new compressor fridge being 500wHr/Day and the roof solar giving ~1000wHr/day on sunny days, the water boiler would more than use any excess so is a good way to maximize the harvest.

With your 750W of solar panels, you could have a Compressor fridge and still have a couple of all-electric showers probably

 

[Deleted member 1368]

I had a similar problem
Fine onmains and 12volt when travelling
Found a clip on u tube were it shows a valve that can stick when not used a lot
Remedy is to tap it with something gently to move the valve
Have a search on u tube for sticking gas valve im sure you will find it but it cured my problem

 

[Cathy]

Question for you 3-Way Fridge Gurus .....
I have a Thetford 3-way Fridge. Think it is a N175 with the internal freezer compartment. It is a model with the Auto Energy select feature.

It doesn't seem to want to always work on gas. Electric (12V and 240V) is fine, but the gas seems a touch unreliable. I sometimes go to the fridge and find it is no longer cold. I have gas in the bottle (right now it is virtually full) and the gas cooker starts no probs so gas is coming out the bottle and regulator.
I tried to start it yesterday and the auto ignition was doing its clicking thing for the 15 seconds and then timing out. I'd try again and same thing again.
When I took the vent off and watched what was happening I could see a spark going on; I could hear the gas coming out, so the basic actions seemed out but the burner just would not light?
This morning I tried again after coming back from driving the van and tried the fridge again and it worked straight away - burner lit on the first or second click.

Any ideas what this intermittant working might to due to? something needs cleaning? servicing? adjusting? I don't really 'do' gas so not familiar with the details of it.

Also, I watched a little youtube video on this kind of thing by someone with the same fridge this morning. it didn't really help, to be honest, but I did notice that he had a cover over the burner/thermocouple assembly part that he took off to show the burner, etc. I don't have any cover on mine? I am wondering if that might have been removed for servicing at some time and never refitted? would not having a cover cause the fridge not to work properly? maybe allow dirt in the area or mess with the airflow and be less efficient? I guess I should buy/make a cover plate to put back.

You don’t say how old your van is, but we had this problem with our 20yr old van and it appeared that the gas system was very sensitive to parking on a slope. If the van was at more of an angle of plus or minus 3 degrees, the fridge would stop working. We added a spirit level to the kit! The garage who checked the gas out for us said newer fridges tend not to be as sensitive.

 

[wildebus]

Apparently around 3 Degrees fore/aft and 6 Degrees side-to side for the typical side-mounted 3-way Fridge are the limits (if you had a fridge in an end-kitchen you would switch the fore/aft and side-to-side numbers).
Therford are also meant to be more sensitive to this than Dometic/Electrolux apparently.

Anyway, that was not the problem, but useful to note for other people who wonder why their fridges sometimes work and sometimes do not.

 

[Markd]

Thanks for the fore-aft figure - I was aware of 3⁰ and was wondering if that was both ways.
In my mind I'd decided that side to side was critical and that as fewer obvious front to back flows that was likely be less important.

I got my Govee thermometer yesterday and have set fridge going this morning - I'll check current tilts which I know aren't perfect at the moment.

Quick update freezer dropped from 25⁰ to 11⁰ in one hour which is pretty satisfying and better than I thought it would be after last week's unmeasured effort.
If it continues at that rate it's going to save me a wrestling match

This beats watching paint dry
-4.6⁰C after 2 hours - so as good as one could hope for I guess.
Mind you all it's doing is cooling the thermometer and some air
At least I know the system is functioning pretty well and soon will have confirmation of minimum temperature at the setting I've chosen and can move thermometer into fridge (not as flush as Wildebus) to see how that's doing.

Obviously cooling food will take longer and that's why we're always advised to pre-chill both food and fridge.

 

[wildebus]

I'm trying to work out the best way to fit a wired temp sensor into a fridge
The obvious way - and what I have done to date - is just through the door opening and rely on the seal closing around the wires, but not sure it does seal fully? (especially with the very heavy cable that victron use on their sensors!)
Might have to just cut the cable and insert a short length of thin cable with thinwall insulation (which will change the sensor reading as relies on level of voltage drop to sense temp change and no calibration option - but end of the day it is about change and not actual values that is monitored, once you know what the sensor temp value actually is in fact)

Your freezer temp drops seem perfect.
You should have bought them when I first posted the link - would have been 30% cheaper

 

[Jenrai]

You guys are not going to believe this! This morning after getting a new pcb (the correct one) I removed the old one and replaced it with the new pcb. Loads of pictures before and marking wires but it all went in. And the good news it all works on all 3 energy sources. Honestly I am chuffed to bits. The least technical person on this forum

A big shout out to everyone on this thread for your advice and support and for listening to me. Free beer when you see me

 

[Markd]

I got a discount down to £11.89 so not too bad
The thermal inertia is quite high and when moving from freezer to fridge it took c30 minutes to come up - I should have left it outside in 25⁰ air for a few minutes if i was that bothered - another downside of being a cheap skate!

Anyway the bottom line is that my fridge-freezer is working fine with an initial cool rate to match the rejuvenated Thetford.
I got down to -18⁰ in freezer but this gave -3⁰ in fridge so my usual running position of about a third of the way round the dial is still a good setting.
It got me thinking as to where the thermostat is placed and I came to conclusion that it would probably be in the fridge any thoughts anyone?

 

[Markd]

You guys are not going to believe this! This morning after getting a new pcb (the correct one) I removed the old one and replaced it with the new pcb. Loads of pictures before and marking wires but it all went in. And the good news it all works on all 3 energy sources. Honestly I am chuffed to bits. The least technical person on this forum

A big shout out to everyone on this thread for your advice and support and for listening to me. Free beer when you see me

Just shows that patience and perseverance pays off - well done!
No longer the least technical person on the forum