Another Gas Fridge Problem!

Discussion in 'Fridges & Ovens' started by DBK, Jun 14, 2018.

  1. DBK

    DBK Funster

    Joined:
    Jan 9, 2013
    Messages:
    11,300
    Location:
    Plympton, Devon
    Ratings:
    +25,198
    An alternative title to this Thread could be "Convince me I don't to spend £150" :).

    Here's the problem. One for the fridge experts.

    Anyone who has followed my trip reports over the last couple of years might recall we have had intermittent problems with our Dometic RM3510 manual three-way fridge when running on gas. The initial problem was getting it to stay alight once lit. We worked out if we let it cool down for twenty minutes after running on electric it would light and stay lit.

    Then on this trip we have experienced three occasions when it wouldn't work properly on gas. It would light and stay lit but it didn't cool things effectively. The top of the flue was hot but the fridge temperature wouldn't go much below 16°C. The fault was not permanent and cleared itself if we left it switched off overnight. The first two times this happened we were on aires so were unable to use EHU.

    Two days ago I made a sort of diagnostic breakthrough by discovering the flame was lighting but only staying at the low level state. My understanding is the thermostat controls the temperature by switching between a high and low flame.

    Further evidence is the last two times I have lit it after an overnight rest I can distinctly hear a gentle roar from the flame which I couldn't when lighting it in its failed state. The fridge would then run perfectly on gas. The first two times also happened after a day of driving on very rough roads and steep hills making me wonder if the fault might be the refrigerant was getting "mixed up" somehow but the last time it failed it was after a day of gentle driving and it began to work as soon we were on EHU and the fridge switched to mains. So I think the failure after the rough roads was just coincidence. The fridge was also level on each occasion.

    My suspicion is the gas thermostat valve is failing. This is a picture of the beast.

    31Zyz3FrhGL.jpg

    There is a little electrical meter on the front of the fridge with a needle which swings across into a green zone when it is operating on gas. It may be relevant to the fault diagnosis that when we first bought the van the needle shot across very quickly into the green zone. These days it only moves very slowly and only just into the green zone.

    Now to the alternative title for this thread. :). I've found a UK supplier of this valve but it is (gulp) £150 although a German supplier is offering them at €140 so if the shipping cost is reasonable I know who I will go to.

    It is now running well on gas after a night on EHU - I intend to keep it on gas until we board the ferry! We also have an electric coolbox so we have not suffered from warm beer while the fridge was playing up.

    So, here's the question: Do you think replacing this valve is the way forward or can anyone think of any other cause for the faults we have seen?
     
    Last edited: Jun 14, 2018
  2. PhilandMena

    PhilandMena Funster

    Joined:
    Feb 9, 2008
    Messages:
    4,063
    Location:
    Corby, Northants
    Ratings:
    +6,903
    I am aware of several failures when on gas and all down to a dirty flue, causing the heat exchange to be significantly reduced. I had a failure on mine too whereby no alarm or warning with a good flame but the fridge suddenly refused to cool. Once the flue was cleaned the problem was solved. You may want to check this before splashing the cash.
     
    • Thanks Thanks x 1
  3. DBK

    DBK Funster

    Joined:
    Jan 9, 2013
    Messages:
    11,300
    Location:
    Plympton, Devon
    Ratings:
    +25,198
    Thsnk you, I forgot to mention I have checked the burner and flu and they are clean. If the flue was blocked it would consistently not work well I think. My fridge works fine on gas - but only after it has had a rest. :LOL:
     
    • Like it Like it x 1
  4. kaasbroodje

    kaasbroodje Funster

    Joined:
    Sep 14, 2013
    Messages:
    1,072
    Location:
    Bristol
    Ratings:
    +1,698
    I've experienced this a few times over the years, always after using the fridge continuously for more than a week or two.
    I've been told that the fridge can work too efficiently, causing the gubbins to freeze and stop cooling (technical description :))
    By leaving it off overnight, the rear can defrost, allowing it to start working again the following day...
    Perhaps related to your problem?
     
    • Thanks Thanks x 1
  5. DBK

    DBK Funster

    Joined:
    Jan 9, 2013
    Messages:
    11,300
    Location:
    Plympton, Devon
    Ratings:
    +25,198
    Interesting thought, thank you. It does work reliably on mains but perhaps the cooling (and freezing) effect is greater on gas?
    I'm playing with the fridge thermostat setting at the moment to get it to a reasonable temperature inside. It was exactly 0°C this morning in the middle of the fridge after a night on EHU which is a bit chilly as it is full of salad stuff. It's now running on gas and after a bit of twiddling the middle of the fridge is around 4°C which is about right.
    I'm using a remote sensor from a cheap weather station to measure the temperature. :)
     
  6. kaasbroodje

    kaasbroodje Funster

    Joined:
    Sep 14, 2013
    Messages:
    1,072
    Location:
    Bristol
    Ratings:
    +1,698
    As I understand it, gas is the most efficient way of cooling.
    If it's not cooling, the obvious action would be to turn it up. Apparently 'less is more' in this case, turning the thermostat down is more beneficial. Our thermostat is set between 2-3 and keeps the fridge around 4°c.
    Monitoring fridge temperature remotely - that would be a nice addition to motorhome 'tech' (y)
     
    • Thanks Thanks x 1
  7. Podney

    Podney Funster

    Joined:
    Feb 21, 2016
    Messages:
    1,092
    Location:
    Uk
    Ratings:
    +2,836
    Beat me! Turned ours down and it seemed to work better.
     
    • Thanks Thanks x 1
  8. DBK

    DBK Funster

    Joined:
    Jan 9, 2013
    Messages:
    11,300
    Location:
    Plympton, Devon
    Ratings:
    +25,198
    It is is turned down to almost minimum now and still only just above freezing. Looks increasingly like the thermostat is goosed. :(
     
    • Nice One! Nice One! x 1
  9. Podney

    Podney Funster

    Joined:
    Feb 21, 2016
    Messages:
    1,092
    Location:
    Uk
    Ratings:
    +2,836
    Sorry,maybe I’m being thick,but earlier you said 4 degrees was about right,so just above freezing is ok isn’t it?
     
    • Thanks Thanks x 1
  10. tonyidle

    tonyidle Funster

    Joined:
    Aug 6, 2013
    Messages:
    5,373
    Location:
    Kendal, Cumbria
    Ratings:
    +7,167
    I'd agree. From your description it's the same as a Thetford fridge l had a lot of trouble with in my last van caused in the end by an incorrect burner being fitted prior to my ownership. There are 3- and 4- slot burners available. Mine was 4 and should have been 3. Symptoms were similar to yours. Incidentally the meter thingy reads the voltage generated by the FFD thermocouple so how high it goes depends on how hot it gets.
     
    • Thanks Thanks x 1
  11. Podney

    Podney Funster

    Joined:
    Feb 21, 2016
    Messages:
    1,092
    Location:
    Uk
    Ratings:
    +2,836
    Dometic.
     
    • Thanks Thanks x 1
  12. namwaldog

    namwaldog Funster

    Joined:
    Jan 2, 2015
    Messages:
    863
    Location:
    Cumbria
    Ratings:
    +2,177
    Is this the part you want?

    http://www.caravan-components.co.uk/Thetford-Fridge-Manual-Gas-Valve-Version-2-and-Thermostat

    A bit cheaper at GBP 62

    I had to search for a part for our fridge and did it thus...

    On Google type in your product name (sometimes pays to keep it to as few relevant words as you can)

    In your case I typed "Dometic RM3510 gas thermostat valve"
    When the results come up, select "Images" see below...

    Untitled.jpg

    Scroll through the images until you find a match and then click on "Visit" which will take you to the site that included the image.

    Untitled 2.png
    Probably 8 in 10 will be a waste of time but you might strike lucky and find the part listed on a small time or even international website that doesn't load in the first few pages of Google if you simply search, for say, " Dometic RM3510 gas thermostat valve for sale"

    Hope this helps
     
    • Thanks Thanks x 1
  13. tonyidle

    tonyidle Funster

    Joined:
    Aug 6, 2013
    Messages:
    5,373
    Location:
    Kendal, Cumbria
    Ratings:
    +7,167
    Too late - edited :D.
     
    • Thanks Thanks x 1
  14. DBK

    DBK Funster

    Joined:
    Jan 9, 2013
    Messages:
    11,300
    Location:
    Plympton, Devon
    Ratings:
    +25,198
    Many thanks for that. It is a Dometic fridge but that much cheaper Thetford links looks exactly the same part. :) I got the £150 quote using an image link but I only looked at a couple. It may be safest to remove the thermostat and send a photo to the supplier and ask if what they have is identical.
     
  15. DBK

    DBK Funster

    Joined:
    Jan 9, 2013
    Messages:
    11,300
    Location:
    Plympton, Devon
    Ratings:
    +25,198
    I may have misled you. :) When it isn't working properly on gas, despite being lit, the internal temperature was typically in the teens. It now seems to be running with a full flame but I'm not sure it is being regulated correctly. The photos below might help to explain this.

    DSC_0342.JPG

    In the above the thermostat is turned almost down to minimum but we have never had to turn it down this far before. Even so the internal temp in the fridge is now cooler than I would like.

    DSC_0343.JPG

    The upper temperature shown above is the ambient temperature.

    I can live with the present situation for this trip. It is running on gas and if I don't turn it off we should be fine. :)
     
  16. DBK

    DBK Funster

    Joined:
    Jan 9, 2013
    Messages:
    11,300
    Location:
    Plympton, Devon
    Ratings:
    +25,198
    But it has worked fine in the past. The problem seems to be intermittent, working one day but not the next .
     
  17. tonyidle

    tonyidle Funster

    Joined:
    Aug 6, 2013
    Messages:
    5,373
    Location:
    Kendal, Cumbria
    Ratings:
    +7,167
    I wasn't suggesting that the jet was the problem. I think you are correct to consider the gas valve.
     
    • Thanks Thanks x 1
  18. Podney

    Podney Funster

    Joined:
    Feb 21, 2016
    Messages:
    1,092
    Location:
    Uk
    Ratings:
    +2,836
    Got it!
     
    • Thanks Thanks x 1
  19. DBK

    DBK Funster

    Joined:
    Jan 9, 2013
    Messages:
    11,300
    Location:
    Plympton, Devon
    Ratings:
    +25,198
    Still working! (The dog is an optional extra for the thermometer. :))

    DSC_0366.JPG
     
    • Like it Like it x 1
    • Funny Funny x 1
    • Nice One! Nice One! x 1

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice