Conrad J Posted November 3, 2019 Share Posted November 3, 2019 Our Thetford hob has decided it would like to have the ignition click away for longer than it used to be happy with before cooking our dinner. Any ideas on how to encourage it to light up straight away? Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 4, 2019 Share Posted November 4, 2019 When the gas-igniter clicks, have you confirmed whether a spark is always produced at the burner? (ie. Does every click produces a spark?) If there’s always a spark per click, then the gas not lighting immediately may be due to how the gas is being delivered to the hob’s burners. If sparking is irregularly produced, then the issue is more likely to be with the ignitin system. Details of your motorhome (make, model, age) might be useful, just in case it’s a known problem. https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/ALL-FORUM-MEMBERS-PLEASE-READ/47195/ (My Rapido has a 2-burner gas-hob with piezo ignition. Lighting the gas burners has always been an art not a science and I’ve never found a technique that guarantees that either of the burners will always light the first time that the igniter button is pressed. There’s no doubt that, when the button is pressed, a strong spark is produced at the burner but, despite trying all sorts of methods and always managing to get the burners to light fairly quickly, I still can’t always get ‘first button-press’ ignition. Now I just let my wife do it as she doesn’t care whether it takes one button-press or five...) Link to comment Share on other sites More sharing options...
Will86 Posted November 4, 2019 Share Posted November 4, 2019 Find a way of allowing the gas to flow before pressing the ignition button. Remember gas does not flow evenly at the start, it can appear in a corkscrew pattern, if the ignition spark operates at the opposite side to the 'actual' gas flow then no flame !! and again this can be repeated until a solid full gas flow is achieved and can take many button presses. Link to comment Share on other sites More sharing options...
tonyishuk Posted November 4, 2019 Share Posted November 4, 2019 I don't think any of my click to light appliances , fire up on the first, second even third click. BBQ, fridge, hob in the mhome all take time. The quickest to light is the hob at home, when it does not light, the gas flame spreader has moved too close to the igniter. Rgds Link to comment Share on other sites More sharing options...
peterjl Posted November 4, 2019 Share Posted November 4, 2019 I would echo comments on reliability of first time piezo lighting.This is why we have defaulted to matches for the hob. Simple and reliable. Peter Link to comment Share on other sites More sharing options...
Alanb Posted November 4, 2019 Share Posted November 4, 2019 Several contributors have mentioned piezo ignition, however our Smev 4 burner hob features electronic ignition. With this type of ignition, the clicking sound is actually that of the spark. One of the burners on our hob does not like being the last to be lit, it fails to light. I attribute this to the dynamic drop in gas pressure when the other burners are already lit. Perhaps it would be worth checking the gas presure delivered from the regulator. Alan Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 4, 2019 Share Posted November 4, 2019 Out of curiosity today I tried lighting the hob burners of my Rapido that had only residual pressure in the gas pipework. Both burners lit immediately... ;-) Link to comment Share on other sites More sharing options...
Alanb Posted November 4, 2019 Share Posted November 4, 2019 Derek, Given your earlier post in which you describe lighting hob burners as an art, could it be that you gas / air mixture is not optimal for ignition, and having only residual pressure resulted in a better mix? Alan Link to comment Share on other sites More sharing options...
Conrad J Posted November 4, 2019 Author Share Posted November 4, 2019 Thanks for the ideas, I’ll check it out. Realised the problem isn’t failure to light the gas, it goes out when you let go of the knob once it has lit, and we have to keep it clicking away for another ten seconds to make sure flame won’t go out. Sometimes is ok, no rhyme or reason why sometimes isn’t. Derek, I did have van details on my profile as you suggested, somehow disappeared! I’ve updated. Link to comment Share on other sites More sharing options...
Alanb Posted November 4, 2019 Share Posted November 4, 2019 Conrad, Normal operation would be to hold the knob in the lighting position for several seconds after ignition, in order to allow the flame failure device to recognise that the burner is alight. If as you suggest, the required interval has lengthened, it could indicate that flame failure device is failing. Alan Link to comment Share on other sites More sharing options...
spospe Posted November 4, 2019 Share Posted November 4, 2019 I have found that pressing the switch to operate the electronic igniter (which 'clicks' at the rate of two sparks per second) gives a slower gas lighting time than tuning on the gas and then pressing the igniter. I put this down to the spark producing a shock wave which blows the gas away from the spark gap and thus delays the arrival of a burnable mixture between the electrodes. This is true of all three gas rings on my Truma Caprice III cooker. Has the Conrad J tried both the above methods of lighting the hob? Edit: took too long posting this reply and now see that it may not be as helpful as I thought due to other posts. Link to comment Share on other sites More sharing options...
Conrad J Posted November 4, 2019 Author Share Posted November 4, 2019 Thanks spospe for the tip, but the ignition starts as soon as you turn the knob. Safety measure I suppose, to stop you having gas coming out without being lit. Link to comment Share on other sites More sharing options...
Geeco Posted November 5, 2019 Share Posted November 5, 2019 In my back garden I have a Weber full size BBQ (as opposed to a Baby Weber in the MH). It is some 20 years old and was taking forever to light. On investigation I noticed that the metal shroud around the igniter has rusted away in part. This appeared to cause the gas to not "bulk up" near the igniter. I fashioned a new shroud and it ignites correctly, but not first click. If all else fails maybe a shroud will help. Having said that does it really matter if it takes a few clicks to ignite. Cheers, Link to comment Share on other sites More sharing options...
Will86 Posted November 5, 2019 Share Posted November 5, 2019 No it doesn't matter, people are more impatient than they were Link to comment Share on other sites More sharing options...
trialsrider Posted November 5, 2019 Share Posted November 5, 2019 I don't know how old your hob is or how much use its had but I've noticed on my hobs that when I've used them all year they take longer to light. To overcome this, i then run an airline under the hob rings and around the jets and blow any debris away from them which may be occluding flow. My hobs are always smev and the rings suffer from corrosion and the subsequent rust and filings need to be cleared out when they build up. I use compressed air to do this as it means you don't have to dismantle the hob rings to do so and risk damaging the flimsy torx head screws holding them on. They work perfectly after this but I suppose not everybody has compressed air in their garage. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 5, 2019 Share Posted November 5, 2019 Conrad’s motorhome is a 2019 Chausson Flash 646 model. His original enquiry did not imply impatience: he merely asked I f anyone could suggest how the motorhome’s Thetford hob (whose gas-burners used to light immediately and no longer do so) might be returned to an ‘instant lighting’ state. Link to comment Share on other sites More sharing options...
ColinM50 Posted November 5, 2019 Share Posted November 5, 2019 Can't add anything to this discussion, but my problem's with the grill. Getting it to light isn't a problem, but keeping it alight is. Tried holding the knob in for half a minute but it still won;t stay alight. All othe rings and the oven are fine, just the grill. Any suggestions welcome Link to comment Share on other sites More sharing options...
747 Posted November 5, 2019 Share Posted November 5, 2019 ColinM50 - 2019-11-05 3:01 PM Can't add anything to this discussion, but my problem's with the grill. Getting it to light isn't a problem, but keeping it alight is. Tried holding the knob in for half a minute but it still won;t stay alight. All othe rings and the oven are fine, just the grill. Any suggestions welcome Check that the thermocouple is in the gas flame. Link to comment Share on other sites More sharing options...
spospe Posted November 6, 2019 Share Posted November 6, 2019 If a burner will light, but not stay lit, it points to a thermocouple problem of some kind. It matters not that it is a hob, grill or oven, if it will not stay lit look to the flame failure device (the thermocouple). In the past, I have had thermocouples move in their holders, such that they were out of the flame and so became ineffective. I have also had one which was in effect disconnected from the gas supply and so could not hold the gas open, Check all connections, wires and switch(es) relating to the defective burner, because that is where the problem lies. Link to comment Share on other sites More sharing options...
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