Bosch HBN435AGB- Bottom Oven Not Working. Please Help!

[zakmuh]

Hi All,

I've got an issue with my Bosch double oven, in which the bottom oven not switching on (red circled switch in the pic). Top one working all fine.

Bottom one used to work fine, then it started to trip the electricity after 5 mins and now its not working at all.

Can I say it could be due to faulty element/element is earthed?

Any advice on this would be greatly appreciated.

Cheers

 

[zakmuh]

Anyone?

 

[terryplumb]

it could be a failed element ,it could be a number of things .are you thinking about repairing it yourself ? the only way to establish what's wrong is by using a multimeter coupled with the knowledge of what to do with it. if you have both you are on , if not you will need to call in an engineer. all the best terry.

 

[zakmuh]

Thanks for your reply Terry. Yes I'm going to do it by myself and I do have a multimeter and do quiet a bit of car and appliances testing using that.

First I'll remove the element and check if the lights at the switch and the inside the oven works. Would there be a separate fuse for each oven?

 

[terryplumb]

element resistance can be measured in situ .how is the oven connected to electric supply , hard wired ? I am not familiar with your oven ,but its unlikely that each element has a fuse.

 

[zakmuh]

Morning.

Ive got an update. Last night, as I mentioned above, removed the bottom oven element and tried to turn it on and it worked - temp light and the bulb inside the oven are working now. So as you've said, this tells us the element is faulty here.

When I had a closer look at element connection point, I can see the red rubbery insulation between the ceramic cover and metal pin (which connects the white wire to it) in one of the tip is deteriorated. This may not have anything to do with it, but I'll try to get a new element and try.

The oven is connected directly to thick grey wire coming from the wall (with a black circular cable connector), behind the oven unit. I had to switch off the kitchen line at main fuse box, before removing the element.

 

[zakmuh]

I think I've SOLVED the issue.

With the idea to sort out the issue another day, I put the element back in. For some reason I felt like to check it again. So I switched on the oven. Surprise....surprise! It worked. I tried to max, 200 degrees, fan kicked in when the temp reached to like 100. So far it works fine - no tripping or anything.

I would see how it goes for the moment. If the problem comes back again, I surely will replace the element. On Ebay it's around £8 and the local spares shop sells it for £15.

Thanks for your advice on this Terry

Zak

 

[terryplumb]

your welcome , zac. its a bit weird though ,if all you did was remove the element ,put it back on and now it seems OK ???? Anyway fingers crossed !

 

[zakmuh]

I'm puzzled here as well. Its a DIY miracle eh! Don't know if it has a computer inside (like in cars) to register any faults and when I operated the oven without the element, it would have cleared issue?

I've used the oven this weekend and so far it's all fine. So yes, fingers crossed!

Cheers

 

[terryplumb]

hi Zak, when the electric tripped ,was it tripping the circuit breaker for oven circuit only. ,tripping a RCD ?. they react to different faults. I suspect it was your RCD ,so you may have leakge to earth on the oven.regards terry.

 

[zakmuh]

What is RCD?

It was NOT tripping the main fuse (which powers the entire house) in the box, it was only tripping one switch (is it called circuit breaker??) which is supplied to all the electrical appliances in the kitchen.

Basically when oven tripped it, double oven unit, microwave, dishwasher, kettle, extractor fan, hob all wouldn't work.

Sorry, I don't know the exact words

 

[terryplumb]

an MCB ( miniature circuit breaker) protects individual circuit against overcurrent, I.e. too much current .so typically you would have several , one or two for lighting circuits , sockets , shower and an oven circuit usually has its own circuit, all mounted in your consumer unit ( fuseboard ) . RCD ( residual current device ) which is also on the consumer unit , alongside the mcb's , protects against current leakage to earth and are highly sensitive. if your electrical installation is outdated you may not even have RCD protection. you also have a main isolator on there ,which you use to turn power off to all circuits .Can you take photo and post on here ? anyway the reason I was asking, was to assist in diagnosing exactly what is going on with your set up.your last post kind of indicates more than one circuit is affected when trip occurs. as electric oven and hob ( assuming its not gas) as well as sockets for kettle etc , are not USUALLY on the one circuit .so if you can confirm exactly what trips , would help.

 

[zakmuh]

Terry, I've some pics here.. The last pic shows the one get tripped when the bottom oven switched on (RCD?).


The second one from left at OFF position (MCB?) is the one for the oven, hob, extractor fan and fridge. I was wrong earlier- kettle and microwave are not connected to this.

The first one on the left at OFF position is the one get tripped when the bottom oven switched on.

 

[terryplumb]

hi ,thanks for pics. the far left one that trips is indeed the RCD .and are you sure that is the ONLY thing that trips ? if you notice the green coloured section on the left of the board ,that denotes the circuits protected by the RCD , and you have two . one marked cooker ,the other marked sockets .if there is a fault on either of those two circuits ,that causes the RCD to trip ,it cuts the power to both circuits ,even though the two mcb's stay in the on position .the other mcbs ,on the red coloured section of the board ,are not protected by the RCD ,and are not connected to it. modern consumer units have 2 RCD 's protecting ALL circuits . hope this gives you a better understanding of your set up , for future .Anyway what does it all have to do with your oven problem ,you may well ask !!! the short answer is the RCD trips when a very small current "leaks " out of a circuit its connected to. This can be a real pain to track down !! failing insulation ,moisture ,faulty swiches ,appliances , wiring issues, even a bulb blowing, to name a few. and to make your life even more complicated ,your problem is intermittent .but it seems to me that changing the element ,if you have further problems ,would be worthwhile. regards terry.

 

[zakmuh]

Terry, I thank you a trillion for all the advice you've given me. Now I think I understand it.

RCD trips only for the bottom oven. So I suspect it'd be the element. If it goes off again, I'll replace it and see what happens then.

Cheers