trialsrider Posted February 4, 2020 Share Posted February 4, 2020 Hi there. Got a new oven. It is the Thetford Duplex with piezo ignition not the 12v one. Igniter on oven and grill just doesn't ignite oven or grill. It did when it was brand new. But now I've ran oven for an hour or two to get rid of that new oven smell it just won't light. Sometimes you can see a spark when the gas is not on but when gas is on it seems to disappear and won't light. If it sparks once it then won't spark again for a minute or so despite numerous presses of button. Is this ignition system similar to a spark plug where there is a gap that needs to be set? Oven lights normally if I use a lighter. Grill is the same. Any ideas ? Link to comment Share on other sites More sharing options...
Ninian Posted February 4, 2020 Share Posted February 4, 2020 Hi, Having just read the operating instructions you have to hold the gas on for 10 / 15 secs before trying to light and if it doesn't light wait a minute before trying again. Possibly you're not leaving it long enough. You could also contact Thetford and describe your fault and seek their advice. Link to comment Share on other sites More sharing options...
trialsrider Posted February 4, 2020 Author Share Posted February 4, 2020 Ninian - 2020-02-04 8:56 PM Hi, Having just read the operating instructions you have to hold the gas on for 10 / 15 secs before trying to light and if it doesn't light wait a minute before trying again. Possibly you're not leaving it long enough. You could also contact Thetford and describe your fault and seek their advice. Thanks. Will try that Link to comment Share on other sites More sharing options...
Keithl Posted February 4, 2020 Share Posted February 4, 2020 Just to confirm, do you get one click and spark for each push of the button, often with a fairly loud noise as the spring loaded plunger resets, or is it a push button giving multiple sparks when held in? If the former then the spark gap will be fairly critical but you may also have a damaged wire to the spark 'plug' and this could have been caused by heat whilst using the oven. If the latter then this will almost certainly have batteries of some kind hidden away, either within the button itself or maybe in a concealed 'black box'. Keith. Link to comment Share on other sites More sharing options...
trialsrider Posted February 4, 2020 Author Share Posted February 4, 2020 Ninian - 2020-02-04 8:56 PM Hi, Having just read the operating instructions you have to hold the gas on for 10 / 15 secs before trying to light and if it doesn't light wait a minute before trying again. Possibly you're not leaving it long enough. You could also contact Thetford and describe your fault and seek their advice. Tried that just now and it made no difference. No spark. I think I'll give Thetford a ring tomorrow. Thanks anyway. Link to comment Share on other sites More sharing options...
trialsrider Posted February 4, 2020 Author Share Posted February 4, 2020 Keithl - 2020-02-04 9:15 PM Just to confirm, do you get one click and spark for each push of the button, often with a fairly loud noise as the spring loaded plunger resets, or is it a push button giving multiple sparks when held in? If the former then the spark gap will be fairly critical but you may also have a damaged wire to the spark 'plug' and this could have been caused by heat whilst using the oven. If the latter then this will almost certainly have batteries of some kind hidden away, either within the button itself or maybe in a concealed 'black box'. Keith. It is the former. Link to comment Share on other sites More sharing options...
Ninian Posted February 4, 2020 Share Posted February 4, 2020 Hi, As an after thought my other van, the cooker had a AA battery in the Igniter system to the spark generator. This was fitted below the cooker on the frame. Link to comment Share on other sites More sharing options...
trialsrider Posted February 5, 2020 Author Share Posted February 5, 2020 Does anybody know what the gap between the sparking electrodes should be ? Can't find this info on any search and Thetford slow to respond to my email query. Link to comment Share on other sites More sharing options...
Ninian Posted February 5, 2020 Share Posted February 5, 2020 Hi, Did you find the AA battery. Link to comment Share on other sites More sharing options...
Keithl Posted February 5, 2020 Share Posted February 5, 2020 Ninian - 2020-02-05 2:45 PM Hi, Did you find the AA battery. Ninian, TR has confirmed he has the single click Piezo style igniter so will not have a battery. Keith. Link to comment Share on other sites More sharing options...
trialsrider Posted February 5, 2020 Author Share Posted February 5, 2020 Ninian - 2020-02-05 2:45 PM Hi, Did you find the AA battery. Definitely no battery. I'm going to have a play with the gap tonight and see if there is any improvement. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted February 5, 2020 Share Posted February 5, 2020 Only two Thetford "Duplex" appliances are marketed - one has piezo gas ignition and the other has 12V ignition. Neither has any form of torch battery. Link to comment Share on other sites More sharing options...
trialsrider Posted February 5, 2020 Author Share Posted February 5, 2020 Thetford have come back to me. Gap should be 4mm. Will check that tonight. Link to comment Share on other sites More sharing options...
trialsrider Posted February 5, 2020 Author Share Posted February 5, 2020 Update. Made sure ignition gap was 4mm. It was this distance so obviously no improvement achieved. I thought it may be an earthing issue so put finger on sparker for grill and hey presto oven sparked. Put finger on oven sparker and grill sparked. So it must be. An earth issue. So What next ? Can anything be resolved without removing oven or is it an oven out job ? Link to comment Share on other sites More sharing options...
Derek Uzzell Posted February 6, 2020 Share Posted February 6, 2020 Did you install the Thetford oven yourself, or is there someone else who did this and who you can ask to investigate the present problem? Thetford’s User Manual includes a SERVICING section that says Spark Ignition (where fitted) Disconnect from gas supply (1). Remove appliance from housing (2). Grill burner - Remove the screw from the bracket and spark ignition probe in the top of the burner. Trace the electrode wire back to the generator and pull off the connector. Oven burner - Trace the electrode wire up the back of the cooker to the generator and pull off the connector. Unscrew the fixing screw on the spark electrode inside the oven cavity, then carefully pull the electrode from inside the oven and remove. Piezo Electric Generator –Remove all electrode wires. Remove the lock nut and carefully remove from panel which suggests that any problems with the piezo ignition system would require the oven to be removed. Thetford warns that the oven MUST be earthed, but I’m not sure whether - if the earthing has not been done adequately in your case - it would affect the piezo gas ignition system. There are plenty of on-line comments about Thetford oven problems, but these generally relate to the oven failing to stay lit rather than the piezo igniter not lighting the gas. The push-button piezo igniter for our Rapido’s 2-burner gas-hob produces a very visible spark at the burner, but the burner often fails to light immediately. Although my wife manages to get the burners to light eventually by repeatedly (and vindictively!) pressing the piezo push-button, it still irritates. I’ve never been able to decide why the burners will light instantly sometimes, but are occasionally so difficult to light. I’ve tried all sorts of ‘procedural’ techniques, but none of them guarantee immediate lighting. However, as your oven won’t spark reliably at the burners, obviously lighting your oven’s burners will be much more problematical. Link to comment Share on other sites More sharing options...
trialsrider Posted February 6, 2020 Author Share Posted February 6, 2020 Derek Uzzell - 2020-02-06 8:45 AM Did you install the Thetford oven yourself, or is there someone else who did this and who you can ask to investigate the present problem? Thetford’s User Manual includes a SERVICING section that says Spark Ignition (where fitted) Disconnect from gas supply (1). Remove appliance from housing (2). Grill burner - Remove the screw from the bracket and spark ignition probe in the top of the burner. Trace the electrode wire back to the generator and pull off the connector. Oven burner - Trace the electrode wire up the back of the cooker to the generator and pull off the connector. Unscrew the fixing screw on the spark electrode inside the oven cavity, then carefully pull the electrode from inside the oven and remove. Piezo Electric Generator –Remove all electrode wires. Remove the lock nut and carefully remove from panel which suggests that any problems with the piezo ignition system would require the oven to be removed. Thetford warns that the oven MUST be earthed, but I’m not sure whether - if the earthing has not been done adequately in your case - it would affect the piezo gas ignition system. There are plenty of on-line comments about Thetford oven problems, but these generally relate to the oven failing to stay lit rather than the piezo igniter not lighting the gas. The push-button piezo igniter for our Rapido’s 2-burner gas-hob produces a very visible spark at the burner, but the burner often fails to light immediately. Although my wife manages to get the burners to light eventually by repeatedly (and vindictively!) pressing the piezo push-button, it still irritates. I’ve never been able to decide why the burners will light instantly sometimes, but are occasionally so difficult to light. I’ve tried all sorts of ‘procedural’ techniques, but none of them guarantee immediate lighting. However, as your oven won’t spark reliably at the burners, obviously lighting your oven’s burners will be much more problematical. No the oven was installed by the converter. He says he never earth's this model and this is the only oven he fits. It would not be difficult to connect an earth lead from base of oven frame to floor of van. I may try that next. He also suggested making sure the electrode is screwed in tight. I will check that later too. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted February 7, 2020 Share Posted February 7, 2020 I can’t see why earthing the oven to the motorhome’s chassis would make any difference as far as the piezo ignition is concerned. As your converter does not do this when he fits the Thetford oven (and, presumably, his other customers don’t have this 'non-sparking’ issue) you can probaly forget earthing and check the electrode tightness. However, as both the oven and grill exhibit the same symptoms, it seems more likely that the piezo igniter itself is the culprit. Link to comment Share on other sites More sharing options...
Will86 Posted February 7, 2020 Share Posted February 7, 2020 Is there air entering the gas flow which ignites if a large widespread handheld flame is offered but fails from a small though powerful spark. Link to comment Share on other sites More sharing options...
Keithl Posted February 7, 2020 Share Posted February 7, 2020 How old is the oven? If still under warranty then return to the converter for him to fix it. Keith. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.