Question - Thetford N150 fridge freezer (1 Viewer)

[Jaws]

We have had an on going problem with our fridge freezer ( yep. the problems just keep on coming for us :-( )
It works REALLY well on hook up ( Indicating the heat exchanger is working perfectly ) and when the motor is running in switches just fine and will maintain what ever temperature it is at, so still no problem.

But..
It has never worked well on gas..
I have had it apart and the gas burner is perfect ( actually, it is very posh stainless steel ) and I get a beautiful two tone blue flame.. The flue gets nice and warm too.

We tried a few things that have been suggested ( including trying to find a 'sweet spot' setting and adjusting the thermostat up and down over a period of several days but not had any luck.

I have contacted Thetford themselves by mail ( the only option offered ) and had NO reply at all.

Foned up a couple of people in the UK who are Thetford repair centres and they could not even give basic information about the thing !

Sooo
Here is the question ( at last !! )

Maureen found a tiny little switch on the side of the control panel mounting.

The only info I can find out about it anywhere is...
It is the balance switch

No one I have spoken to has ANY idea what that switch is, let alone what could possibly be causing the poor performance of the unit on gas

 

[Jaws]

Ok.. now know what the switch is.. Apparently it is a heater element round the freezer door ( !!! ) in case the door freezes closed ..

great ..
Now all I have got to do is get the bloody thing to freeze in the first place !!

 

[DanielFord]

I am intrigued, as you say, the heat exchanger must work, so why not on gas? Ours seems to work better on gas than on EHU. I can't think of anything else to suggest, it is a real mystery, I shall watch this thread with interest as I am keen to know the answer now.

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[icantremember]

Hi John, seems like you are collecting problems!

You mention the flue getting warm on gas, but is the pipework and heat exchanger getting HOT? If not then maybe the flame is just not in the correct position.

 

[Jaws]

I am wondering if the Thetford fridge is particularly sensitive to being level.
We found that while we were told the Dometic had to be level, that close enough was good enough for it to work really well

Must admit that while on the road and making nightly stops we kinda do not really bother too much..
Perhaps this unit really does need to be on the level to get the best from it..
If that is the case it is a bloody stupid model to fit in a motorhome !!

Has anyone else had issues with any Thetford fridge freezers that need to be really level to work properly ?

 

[Jaws]

Hi John, seems like you are collecting problems!

You mention the flue getting warm on gas, but is the pipework and heat exchanger getting HOT? If not then maybe the flame is just not in the correct position.

That is something I am gonna be checking soon
The flame is good, is a good colour and seems perfect, but I have noticed there is a pressure control valve for the gas so it MAY be it is not getting enough of a flame

Gonna get Darrell to put his pressure checker on it and seeing exactly what it is set at compared to what it should be ( which I am gonna have to get info on )

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[rb62]

Interesting you say there is a pressure valve for the fridge/freezer as ours stops working on gas while the hob and heating will still work as there is still some gas in the bottle!

 

[Jaws]

I think they all do that RB..
Certainly all the vans I have had have done the same..

Interestingly, the fridge had worked reasonably well for a day or so on the way home, then the Spanish bottle ran out and I switched it back over to the refillable system which was about half full.. it was then we started seeing the problem start again.
Could be a clue

 

[Lenny HB]

The Spanish bottle would have been butane which has a higher calorific value than propane, as you probably know we used to run butane at 28mb & propane at 37mb. Now we run both at 30mb, so when on propane it could be like you think it's just not getting enough gas pressure.

Yet to see a grill that actually works since 30mb regulators were introduced.

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[Jaws]

Noooo.. Spanish bottle is Propane .. We do not go with the butane option at all as it does not like gassing at low temperatures ( and up in the mountains of Spain it gets DARNED cold !!! )

 

[Red Dragon]

Had a very similar problem with mine,and the cure was to make sure the Van was within 2 Degrees laterally not so critical lengthways and not had a problem since,HTHs

 

[SandraL]

When we came back from Spain in Jan we ran out of gas on refillable cylinder, Changed to new cylinder , filled in uk and all ok . At home found "empty" cylinder had about 1 or 1.5kg of liquid lpg. I assume that when we filled up on way down in France we got a mixture of propane and butane. In coldish weather propane gassed off ok but the butane wouldnt. We noticed it when gas water heater/space heater failed to light.

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[jonandshell]

I reckon our Thetford N140 is more sensitive to tilt than the Dometic in our old van.
But shouldn't that be the case on all power modes?

 

[tonyidle]

I had this issue with our Thetford fridge. The flame was perfect, easy to light, lovely blue flame, everything - except the freezer produced condensation only & no ice. Eventually I took out the burner & cleaned it thoroughly. There was a tiny dirt particle of dirt in the jet. Once that was cleared the flame size increased & it has been fine ever since. I'm pretty sure you're having the same trouble.

 

[Lenny HB]

I reckon our Thetford N140 is more sensitive to tilt than the Dometic in our old van.
But shouldn't that be the case on all power modes?

Agree if it works on other power sources can't anything to do with leveling.

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[PeteH]

Have you checked the size of the flame? Perhaps have a look at another fridge? and compare. What appears to be happening is that the AMOUNT of TOTAL heat is insufficient to make the evaporator work properly, The function of this type of "fridge requires a Certain volume of total (Boyles or Charles Law?) heat to efficiently evaporate the liquid in the coil, that seems to be happening with the 230 and 12V. which would rule out a gas leak (no cooling at all).

I am NOT advising this, BUT if say extra heat was applied, eg; with a blow torch (NO!!) you may find that the fridge would start to cool down!. Low gas pressure OR a partially blocked jet (or even the WRONG size of jet?) would give this effect. The effect of low pressure will likely be more critical with the fridge than any of the other appliances?.

Dirt (Rust Debris etc) in the upper flue restricting the passage of hot gases might also have some effect so cleaning the flue to improve hot gas flow might help?.

Pete.

 

[SMB]

We have had an on going problem with our fridge freezer ( yep. the problems just keep on coming for us :-( )
It works REALLY well on hook up ( Indicating the heat exchanger is working perfectly ) and when the motor is running in switches just fine and will maintain what ever temperature it is at, so still no problem.

But..
It has never worked well on gas..
I have had it apart and the gas burner is perfect ( actually, it is very posh stainless steel ) and I get a beautiful two tone blue flame.. The flue gets nice and warm too.

We tried a few things that have been suggested ( including trying to find a 'sweet spot' setting and adjusting the thermostat up and down over a period of several days but not had any luck.

I have contacted Thetford themselves by mail ( the only option offered ) and had NO reply at all.

Foned up a couple of people in the UK who are Thetford repair centres and they could not even give basic information about the thing !

Sooo
Here is the question ( at last !! )

Maureen found a tiny little switch on the side of the control panel mounting.

The only info I can find out about it anywhere is...
It is the balance switch

No one I have spoken to has ANY idea what that switch is, let alone what could possibly be causing the poor performance of the unit on gas

I have contacted Thetford THREE times by email regarding a problem with the interior lights on my N3112 fridge and STILL haven't received a reply. The van is under warranty and since the dealer couldn't help either (other than give me contact details for Thetford, oh how I laughed) they can sort it out. PS this is the second Thetford fridge in two years I have had fitted, the first just gave up

 

[Jaws]

I reckon our Thetford N140 is more sensitive to tilt than the Dometic in our old van.
But shouldn't that be the case on all power modes?

Yesss.... except when we are on hook up we are always dead level.. When we are travelling and just doing a wild stop over we park at any old angle !

Interesting posts from Tony and Lenny
Must admit I never took the burner right apart, just took the cowlings off and cleaned and inspected the burner in situe
When I have another look at it I shall take it right apart and use a jet cleaning needle ( I think I can go down to about a 30 size which in real terms is about 2 human hairs !! LOL !! ) to make 100% sure it is all spotless

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[PeteH]

It`s a Bit of an Anomaly. I know but this category of refrigerator Needs HEAT to make it COOL!! It`s all to do with the combination of gas mixture in the system separating and combining throughout the cycle (Partial pressures for anyone who is remotely interested!!) and the "driving force" is the amount of HEAT imparted to the Coil in the evaporator.

We had to cover the "science" as part of the Certification (Yes! I am Certified!!) as a Marine Engineer, A VERY long time ago!!

Pete

 

[BigClick]

Agree if it works on other power sources can't anything to do with leveling.

Doesn't the requirement for being level come from the fact the flame will always be vertical (like water always being level)? In which case the fuel type could be a factor because the electric element would be tolerant of angles?

 

[Jaws]

The Thetford is an Absorbtion type.. Basically it requires heat to make the amonia/hydrogen and water hot enough to start evaporation which then does the biz .. When on leccy the only difference is the heat source, so reckon those who have said the gas flame is not big / good enough have got it bang on.
I am sure one day it will stop bloody raining here and then I will take a good gander again

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[Neckender]

I would take the burner and burner supply pipework out clean and blow the jet and pipework out then reassemble this should cure the problem.

It only needs the slightest bit of dust in the pipework and you will have problems.

John.