fairweather camper Posted August 2, 2012 Share Posted August 2, 2012 Hi All, I hope you can help me (again), while away for a few days our fridge started playing up on gas, it would light but not stay lit, when we got home Hubby cleaned it all and blew it with a compressor, now as soon as you switch it to gas it lights by itself without pressing the knob, but it then wont turn off until you switch the gas off at the manifold. We are hoping to go away again next week and can't get anybody to look at it for 3 weeks, please can anyone help. It is an Electrolux C40/110 type, model no RM6401L it is about 10yrs old. It works perfectly on 240v and 12v. Thanks Val 8-) *-) :'( Link to comment Share on other sites More sharing options...
Geoff Cole Posted August 2, 2012 Share Posted August 2, 2012 Hi Val, From what you say it sounds like the thermocouple has failed. This device shuts the gas off in the event of flame failure. You may have disturbed it when cleaning the burner, the capillary pipe from the gas valve to the thermocouple may have broken of due to corrosion. The replacement is available from www. partsmaster.co.uk part No 5031-6875-7211-0 price £36.99 plus the inevitable vat and p&p. regards Geoff C Link to comment Share on other sites More sharing options...
fairweather camper Posted August 2, 2012 Author Share Posted August 2, 2012 Thanks Geoff, much appreciated, is it easy to fit a new one, hubby reasonably good at DIY on the Van. Regards Val Link to comment Share on other sites More sharing options...
Guest peter Posted August 2, 2012 Share Posted August 2, 2012 You may have displaced it when cleaning. It must be in the edge of the flame to work correctly. £39+ seems a bit steep. If it has gone have a look in B&Q etc as they are pretty universal bits of kit, just make sure the threaded bit on the end is the same. Worth a try and shouldnt cost more than about a fiver. Link to comment Share on other sites More sharing options...
Geoff Cole Posted August 2, 2012 Share Posted August 2, 2012 Hi Val, you will most likely need to take the fridge out to fit it not a difficult job but fiddly make sure gas connections are tight but do not over tighten. its worth taking the gas jet out blow out with airline and clean the flue whilst its out. Make sure that the thermocouple is properly located, its tip should be in the flame. I agree with Peter that the part is pricey, I think it highly unlikely that B&Q would even know what a thermocouple is. I always use specialist parts suppliers when sourcing domestic spares. Unfortunately gas spares particularly electrolux( dometic) are pricey for what they are a normal gas cooker or gas fire themocouple is around £40.00 it is essential to get the right one as the temperature operating range varies between appliances. Regards Geoff C Link to comment Share on other sites More sharing options...
Geoff Cole Posted August 3, 2012 Share Posted August 3, 2012 Just a couple of points on fridge problems. Problems with the pilot light on fridges not staying on can be caused by rust particles falling down the flue and preventing the flame from heating the thermocouple correctly it will also cause the flame to burn incorrectly and produce a yellow or dirty flame. Giving the flue and burner a good clean will usually cure the problem. If it still persists then it is usually the flame failure device (thermocouple) that has failed as seems most likely in Val's case. Fridges in campers are not in the best environment they get bounced about which loosens any debris in the flue pipe which drops onto the burner and damp when not being used can cause corrosion in the flue. I made plywood panels which I replace the outside vents with in the winter to keep the damp out from the back of the fridge,I find it also helps keep corrosion at bay if the fridge is on 12v periodically in the winter when taking it for a run to help keep the workings dry. Geoff C Link to comment Share on other sites More sharing options...
fairweather camper Posted August 3, 2012 Author Share Posted August 3, 2012 Thanks to everyone who has replied to my post, much appreciated. Val Link to comment Share on other sites More sharing options...
fairweather camper Posted August 26, 2012 Author Share Posted August 26, 2012 Hi Guys, Well I did what was advised and fitted a new thermocoupler, no problem, lit the fridge, and everything seemed ok, turned the fridge off, but when we checked, the pilot light was still on albeit very faint, the only way to turn it off is by turning off the stop valve in the wardrobe. Can anyone shed light on this for me please. Im starting to tear my hair out, as we cannot get anyone to look at it for us, so will have to do it ourselves. Thanks in advance Val Just gone to try the fridge again, and as soon as i turn the fridge to gas it lights by itself, and wont turn off. so it is exactly as it was before we fitted the thermocoupler. Link to comment Share on other sites More sharing options...
Basil Posted August 26, 2012 Share Posted August 26, 2012 That is because, despite the well meaning comments, it could never have been the thermocouple (which on failure would not allow the flame to stay alight) but can only be the flame failure valve letting by. The thermocouple is not a capilery tube at all, it is a concentric pair of wires (effectively one wire inside a hollow wire) that at the tip is made from disimillar metals which are fused together. Heating this tip causes a small electric current to flow, due to the dissimilar metals, which in turn powers a small electro magnet inside the Flame Failure Valve and this holds the valve that you press against it when you push the FFV button (knob) in and is why you have to hold the button in for a few seconds to enable sufficient current to flow to hold the valve open. Removal of the flame results in no current and therefore no magnetic field to hold the valve open and hence it will shut off so no gas. Clearly gas being present all the time, to a greater or lesser extent means the flame failure valve is not shutting off properly so is the culprit. Not a difficult job to change but will mean pulling the fridge forward and breaking and remaking two gas joints, so if you are not competent to do this, then you need to obtain someone who is. As you have fitted a new thermocouple you must have gained access to the rear of the valve so must have seen the two joints that need to be seperated as the thermocouple connects to the base of the valve (normally). Bas Link to comment Share on other sites More sharing options...
Brambles Posted August 26, 2012 Share Posted August 26, 2012 If you go back to the thermostat where you connected the thermocouple you should be able to with extremne care dismantle the flame failure valve. It wil have a 12 volt coil solenoid assembly around it. This needs to be removed and I think the valve comes out with it. If not you need to gently pul it out with needle noded piers . I suspect you have blown dirt back into this when playing with compressed air at the burner end. The operation is such that pressing the thernostat knob to ignite the gas opens this valve, the thermocouple when heated expands the contents of the bulb in the flame and it transfers the pressure to a small diaphram and pin at the other end,. The pin projects and operates the valve to keep it open. When the flame goes out then the pin retracts as the contents of the thermnocouple cools and the valve closes. However, in your case I think it is not closing correctly and is most likley sticking due to dirt. When you switch off the fridge or select another power source then the solenoid comes into play closing the valve. The solenoid on its own can close the valve, but it cannot open it fully as requires the thermocouple to operate or the knob to be depressed. This is a typical description so hope it helps you sort out the fault. Do be aware this is gas you are working with so be careful and if any doubt get a gas engineer to look at it. The solenoid part can be quite fragile If you need a new flame fail valve they are available separately from rest of the control unit, but suspect a clean out is all it needs. To remove you remove the thermocouple connection and then gland it screws into I believe is then removed. The solenoid coil can then gently be extracted, next is the valve assembly. DO NOT use compressed air to blow out any dirt, use puff and a straw, and finally turn on the gas and use the gas pressure to blow any dirt which is left. Do be careful! Link to comment Share on other sites More sharing options...
Basil Posted August 26, 2012 Share Posted August 26, 2012 With the greatest respect Brambles your description of operation is incorrect. The thermocouple is as I described earlier and has no connection with the thermostat other than the thermostat is built into the same unit on this particular model, there are no'contents' to expand in the 'bulb' of the thermocouple it is purely a wire within a wire. The thermostat capilary tube only varies the thermostat valve to control temperature it has no bearing on the thermoelectric flame failure device. The thermocouple is connected to the FFD which contains the electromagnet powered by the thermocouple this is a sealed unit and has the gas valve attached, this can be seen in the exploded diagram part number 500 http://www.leisureshopdirect.com/caravan/cooling/Dometic_Caravan_Fridge_Spares.aspx?pdf=14375&pdf_page_id=9196&dpn_id=1981&sch=1 it is the valve at the top of this (item 500) that is not closing off properly. You may also note from the same exploded diagram that the thermostat capillary is shown as a coiled up tube near to the front left of the main body of the combined thermostat/ FFD, this tube goes into the fridge cabinet and senses the temperature within there NOT to the gas flame. I also believe it highly unlikely that you will have blown dirt from the burner back up to the FFD, however dirt or gum (from the gas) could well be on the valve or seating as something is stopping the valve from shutting the gas off, so there could be several possibilities including a broken or missplaced spring. You can strip the FFD (i.e.remove 501, 444 and 500) but the electromagnetic coil and the valve are a sealed unit so you can only clean the face of the valve and the seat it shuts onto. But be aware that there is an 'O' ring seal that can be damaged or not reseal correctly so having spares available is advisable. If you are not experienced with this sort of device then I would strongly advise you to either change the complete valve or contact someone who is competent to work on it. Bas Link to comment Share on other sites More sharing options...
Brambles Posted August 26, 2012 Share Posted August 26, 2012 Whatever, I am correct in what I have said. End analysis of the area of probable fault is the same as yours. Jon. p.s. The thermostat's thermo couple (the coil you refer to) operated in teh same way as teh thermocouple for the flame failuer device. A thermostat will have a larger bulb atth temperature monitoring end and usually bellows fitted at teh thermostat end. The Therocouple for teh flame failure as a much higher change in temepratire is uses as a smaller bulb and tiny bellow arangement at the valve end with as I described a pin which will protrude when operating in a flame. It may actually be more like a piston than a bellow which operates the pin. The point is a pin extends when the other end is heated. So really is a very close cousin, almost a brother to the thermostat's thermocouple. Link to comment Share on other sites More sharing options...
Brambles Posted August 27, 2012 Share Posted August 27, 2012 my p.s. spellling corrected as run out of edit time. p.s. The thermostat's thermocouple (the coil you refer to) operates in the same way as the thermocouple for the flame failure device. A thermostat will have a larger bulb at the temperature monitoring end and usually bellows fitted at the thermostat end to give a fine comtro of movement v temperature. The Thermocouple for the flame failure has a much higher change in temperature and it uses a smaller bulb and tiny bellow arangement at the valve end which as I described has a pin which will protrude when operating in a flame. It may actually be more like a piston than a bellow which operates the pin. The point is a pin extends when the other end is heated. So really it is a very close cousin, almost a brother to the thermostat's thermocouple. Electric thermocouples are often used along with electronics to monitor them, but in a flame failure device they are not used as they must operate when there is a loss of electrical power. Link to comment Share on other sites More sharing options...
Basil Posted August 27, 2012 Share Posted August 27, 2012 Sorry Brambles, but you are not correct. The thermostat does NOT use a thermocouple it uses a liquid filled cappilary tube, with or without an end bulb according to the contents of the tube, and bellows. The liquid, in a thermostat capillery, does indeed expand on temperature rise thus operating the bellows and valve. A thermocouple is a completely different device working on a different principle see definition of thermocouple http://www.allwords.com/word-thermocouple.html Although, as you put it, the end result appears to give the same outcome I believe it is important that correct information is given so that the OP understands what he is dealing with when working on a possible volatile situation. There is a Flame Supervision Device that works on the principle you have described (the liquid used to be Mercury, due to its exponential expansion charecteristic, in the sensing capillery but that is now normally volotile alcohol or water) but this is normally used in a situation where a solenoid operated gas burner needs to be supervised for outage, e.g. a gas oven burner (although motorhome/ caravan ovens usually use thermocouple operated FFD's). However this is NOT a thermocouple which is the device I have described and is shown in the exploded diagram, link in my previous posting, for this refridgerator. If anyone is interested in learning about the different devices the following may help your understanding the Thermoelectric valve and thermocouple is shown on page four, a Vapour/ Liquid Expansion Valve is shown on page eight and a thermostat is shown at the top of page nine http://www.radmidlands.co.uk/ControlsDom.pdf The device fitted to this particular refridgerator is a combination of the FFD and a thermostat, however the thermostat plays no part whatsoever in 'supervising' the flame. Bas P.S. Edit to clarify and spelling correction Link to comment Share on other sites More sharing options...
Brambles Posted August 27, 2012 Share Posted August 27, 2012 Sorry Basil, all due respect etc, but page 4 (and 5) are totally wrong. I gave up reading any further. I am correct all I can do is repeat what I have already said. Look at the diagram on page 2 of your link. It is not an electric thermocouple. There is no coil in that particular valve. It is all mechanical. A thermoelectric valve is very similar but contains a solenoid as well to operate the valve from an additional electrical supply. The coil as shown in your earlier parts list is NOT powered from an thermoelectric thermocouple 'Seebeck effect' (which would not have the power to do so anyway). The thermocouple fitted in the fridge being discussed and many others is the expansion type thermocouple as I have already stated. As a very respected poster on these threads once said, when Brambles speaks you would do well to not say a word, sit back and listen (or words to that effect). I am beginning to agree. I am of the belief you are misreading my posts because you have a fixed wrong idea of what is fitted in these fridges and I am at a loss how to persuade you where you have gone down the wrong track not helped by misinformation on the internet. I just wish I could find a picture on the internet showing what I have desribed in detail. I think the best plan is for you to obtain a thermocouple which you beileve is concentric cables and cut it open, but 1st heat the phial end and see what happens at the other. Jon. p.s. "The device fitted to this particular refridgerator is a combination of the FFD and a thermostat, however the thermostat plays no part whatsoever in 'supervising' the flame. " Can I jusy clarify this as no where did I say it did. What it does do though is control another valve which alters the flame height/gas flow. I referred to the thermostat because the capilliary tube and phial is similar to that used in the thermocouple used for flame failure in principle of operation. For flame failure it is just a much smaller phial needed and is usually steel not copper so it can withstand the heat of the flame. Link to comment Share on other sites More sharing options...
Basil Posted August 27, 2012 Share Posted August 27, 2012 Brambles, with the greatest respect I have cut open all types of valves for over 40 years, for 20 years training gas engineers to HNC level, I do not need to do it now! The solenoid (electromagnetic coil) is part number 500 in the exploded diagram, it is a single sealed unit and is replaceable as a whole, there is no seperate coil. Once again, however you may have been right on other matters, on this occasion you are completely wrong! Bas P.S. Due to crossed post. At no time did I say you said about the thermostat supervising the flame I was simply pointing out that it didn't and that was the only part of that valve that has a capillery, the FFD is a thermocouple operated valve and has no phial or capilery tube. Link to comment Share on other sites More sharing options...
Brambles Posted August 27, 2012 Share Posted August 27, 2012 Part 500 does not contain any electric coil. Link to comment Share on other sites More sharing options...
Basil Posted August 27, 2012 Share Posted August 27, 2012 I suggest you take your own advice and cut one open, as I have, you will then see how wrong you are! Also perhaps you could explain why the description for part 500 says 'mounting for magnetic insert'. Bas Link to comment Share on other sites More sharing options...
bob b Posted August 27, 2012 Share Posted August 27, 2012 I always understood that a thermocouple works the way Basil descibes. Anyway, I just replaced mine as the gas wouldn't stay alight when operating on LPG. It works fine on 240 & 12 volts. Had I tested the original first I would have discovered that there is nothing wrong with it!I checked the gas control valve and found that the solonoid coil is 'open circuit'. I think the meter reading should be something like 25 - 30 millivolts. I'll make some enquiries on Wednesday about a replacement solonoid assembly. Although I've got a sinking feeling that I'll have to buy the complete control valve at £152.00 odd as they won't just sell the solonoid assembly. Link to comment Share on other sites More sharing options...
bob b Posted August 27, 2012 Share Posted August 27, 2012 Brambles - 2012-08-27 7:58 PMPart 500 does not contain any electric coil.The coil is shown as part 444. Its not a good drawing of it though! Link to comment Share on other sites More sharing options...
fairweather camper Posted August 27, 2012 Author Share Posted August 27, 2012 Hi Thanks to you both for your information, you will be pleased to know that we have cleaned and blown relevant parts and the Fridge is now working well, I could not see any dirt or scum, but obviously there must have been something stopping it from turning the gas off completely. Thanks once again for your help, much appreciated. Val Link to comment Share on other sites More sharing options...
Basil Posted August 27, 2012 Share Posted August 27, 2012 bob b - 2012-08-27 8:04 PMI always understood that a thermocouple works the way Basil descibes. Anyway, I just replaced mine as the gas wouldn't stay alight when operating on LPG. It works fine on 240 & 12 volts. Had I tested the original first I would have discovered that there is nothing wrong with it!I checked the gas control valve and found that the solonoid coil is 'open circuit'. I think the meter reading should be something like 25 - 30 millivolts. I'll make some enquiries on Wednesday about a replacement solonoid assembly. Although I've got a sinking feeling that I'll have to buy the complete control valve at £152.00 odd as they won't just sell the solonoid assembly.Depending on your model of refridgerator, you should be able to obtain a spare electromagnetic coil assembly, that is what is shown on the exploded diagram, there are other diagrams for other models you can look yours up. I also believe you can buy the parts cheaper than they are offered for on that particular websitebob b - 2012-08-27 8:07 PMBrambles - 2012-08-27 7:58 PMPart 500 does not contain any electric coil.The coil is shown as part 444. Its not a good drawing of it though!Yes I saw that but I believe that part 444 may be an interuptor (notice it is fitted between the coil pack and the thermocouple itself), used when a suplementary circuit is needed to interupt the FFD, such as when an electronic flame sensing circuit (flame rectification or flame conductance) is used.Although it is shown in the exploded diagram, there is no description or part 444 shown in the parts list for that fridge, so it may be that the same diagram is used for more than one fridge but only the relevent parts are listed. But this is a 'best guess' on my part for that information.Bas Link to comment Share on other sites More sharing options...
Brambles Posted August 27, 2012 Share Posted August 27, 2012 Val, glad you have it all fixed. Must be a relief as parts are so expensive. Link to comment Share on other sites More sharing options...
bob b Posted August 27, 2012 Share Posted August 27, 2012 Thanks for your response Basil. Oddly enough I was working on the fridge today and was using that very diagram, so recognized the 'coil' from the very poor drawing. Its the RM 6401 jobbie. Link to comment Share on other sites More sharing options...
Basil Posted August 27, 2012 Share Posted August 27, 2012 fairweather camper - 2012-08-27 8:08 PM Hi Thanks to you both for your information, you will be pleased to know that we have cleaned and blown relevant parts and the Fridge is now working well, I could not see any dirt or scum, but obviously there must have been something stopping it from turning the gas off completely. Thanks once again for your help, much appreciated. Val I am pleased it is working for you now, it doesn't need much to hold the valve just off its seating. Good luck. Bas Link to comment Share on other sites More sharing options...
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