Hello everyone , I have some questions generally about pyrolytic cleaning ovens and following on from that particular questions on this model oven - SMEG SCP109SG8.
I understand that during the Pyro cleaning process the oven heats up to around 500 degrees. Looking at manufacturers bumpf they say oven door glass should not exceed 55 degrees and should be touchable. Yesterday decided to give oven a pyro clean ( maybe do this twice a year). It takes while and I needed to pop out for a few mins. when I returned the smell of heat was apparent and when I entered the kitchen everything smelt hot. Whilst I was gathering my thoughts suddenly all the electrics went off. I am reasonably proficient with electrics and found the RCD had tripped in consumer unit. The oven door was too hot to touch and the adjacent appliances , a fridge and a dishwasher were hot to the touch and the gas hob on top of the oven also had hot metalwork. The MCB for the oven had not tripped but I decided to flick it off and then reset RCD. All power came back on. As part of the Pyro clean it locks the door until the internal temp has cooled down but on this occasion even after half an hour it still had not unlocked. So I assume something had caused the oven the get even hotter than normal resulting in adjacent equipment getting hot , the oven door becoming untouchable and the excessive time for the door to unlock. No error codes were posted on the oven display and the only thing that saved a possible fire was the RCD tripping.
So thats what happened , now I'm trying to get to the bottom of the cause and since the RCd tripped my first assumption is that an element has gone duff.
But if it was an element gone duff then its failure mode could be go high resistance or open circuit or either of these with a path to earth hence RCD trip. I wouldn't expect it to go short circuit or even partial short circuit or the MCB should trip. Anyway I guess it could be a control problem but I would have thought there would be internal safety circuits that would shut oven off if over temperature. the model no is SMEG SCP109SG8.
So questions which occur to me are:-
1. Does anyone know which heating elements are used during PYRO clean. This oven has 3 elements , fan element at rear , bottom element and grill element.
Are all elements used or only one or two?
2. This brings up other questions , I believe the three elements are 1.2 kw base, 2 kw fan element , 1.8 kw grill element.
the oven is powered from a 13 amp socket which I associate with max 3kw capability. So I guess all elements could be used if they were all monitored / controlled.
3. An associated question / frustration is that in the manual for this oven no mention is made of its Kw rating or how many amps it draws max , which is I guess when its doing a PYRO clean. the only thing it mentions is that the supply cable should be 1.5mm CSA ??????? Now I've always associated this cable with lighting circuits , not power circuits. I see that this size cable is rated around 20 amps max. The odd thing is that I stumbled upon an Australian version of the manual and though it still doesn't give a Kw rating or amps required it does state that 2.5mm cable should be used. I know this last point doesn't really have any bearing on the initial fault but thought I'd mention it.
I will get chance to look at problem this weekend and will start by metering each element for paths to ground. if all check out OK then it may be a control problem or intermittent problem to ground in an element. I will have to decide whether its an economic repair as the cooker is 8 years old. Its certainly made me question how safe pyrolytic ovens are. Any thoughts on any aspect appreciated. thanks.
I understand that during the Pyro cleaning process the oven heats up to around 500 degrees. Looking at manufacturers bumpf they say oven door glass should not exceed 55 degrees and should be touchable. Yesterday decided to give oven a pyro clean ( maybe do this twice a year). It takes while and I needed to pop out for a few mins. when I returned the smell of heat was apparent and when I entered the kitchen everything smelt hot. Whilst I was gathering my thoughts suddenly all the electrics went off. I am reasonably proficient with electrics and found the RCD had tripped in consumer unit. The oven door was too hot to touch and the adjacent appliances , a fridge and a dishwasher were hot to the touch and the gas hob on top of the oven also had hot metalwork. The MCB for the oven had not tripped but I decided to flick it off and then reset RCD. All power came back on. As part of the Pyro clean it locks the door until the internal temp has cooled down but on this occasion even after half an hour it still had not unlocked. So I assume something had caused the oven the get even hotter than normal resulting in adjacent equipment getting hot , the oven door becoming untouchable and the excessive time for the door to unlock. No error codes were posted on the oven display and the only thing that saved a possible fire was the RCD tripping.
So thats what happened , now I'm trying to get to the bottom of the cause and since the RCd tripped my first assumption is that an element has gone duff.
But if it was an element gone duff then its failure mode could be go high resistance or open circuit or either of these with a path to earth hence RCD trip. I wouldn't expect it to go short circuit or even partial short circuit or the MCB should trip. Anyway I guess it could be a control problem but I would have thought there would be internal safety circuits that would shut oven off if over temperature. the model no is SMEG SCP109SG8.
So questions which occur to me are:-
1. Does anyone know which heating elements are used during PYRO clean. This oven has 3 elements , fan element at rear , bottom element and grill element.
Are all elements used or only one or two?
2. This brings up other questions , I believe the three elements are 1.2 kw base, 2 kw fan element , 1.8 kw grill element.
the oven is powered from a 13 amp socket which I associate with max 3kw capability. So I guess all elements could be used if they were all monitored / controlled.
3. An associated question / frustration is that in the manual for this oven no mention is made of its Kw rating or how many amps it draws max , which is I guess when its doing a PYRO clean. the only thing it mentions is that the supply cable should be 1.5mm CSA ??????? Now I've always associated this cable with lighting circuits , not power circuits. I see that this size cable is rated around 20 amps max. The odd thing is that I stumbled upon an Australian version of the manual and though it still doesn't give a Kw rating or amps required it does state that 2.5mm cable should be used. I know this last point doesn't really have any bearing on the initial fault but thought I'd mention it.
I will get chance to look at problem this weekend and will start by metering each element for paths to ground. if all check out OK then it may be a control problem or intermittent problem to ground in an element. I will have to decide whether its an economic repair as the cooker is 8 years old. Its certainly made me question how safe pyrolytic ovens are. Any thoughts on any aspect appreciated. thanks.