Gas hob problem

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bmcecosse
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Gas hob problem

Postby bmcecosse » Mon Sep 16, 2013 2:54 pm

Any of you know about gas hobs?? Daughter just bought a flat - all 4 gas rings light up ok with good flame length with the automatic sparking when the knob is pushed down and turned - but NONE of them will stay alight when the knob is released. Is there a common link that would affect all 4 rings....? The flames appear to wash over the tips of the little sensors - but even after a few minutes - the gas is still cut off as soon as the knob is released..... Any/all suggestions very welcome.....
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LouiseM
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Re: Gas hob problem

Postby LouiseM » Mon Sep 16, 2013 3:30 pm

Just did a google search for similar problems and it sounds like the thermocouple has stopped working - this is what keeps the flame alight after ignition so will effect all the rings at the same time.


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simmitc
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Re: Gas hob problem

Postby simmitc » Mon Sep 16, 2013 3:55 pm

"Flame Failure Device" safety feature. You have to keep the knob pressed with the gas alight for a few seconds until it is warm enough to stay alight on its own. If 5-10 seconds doesn't work, then there is a fault.

Matt
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Re: Gas hob problem

Postby Matt » Mon Sep 16, 2013 4:08 pm

I don't know the regulations etc... but you may find its illegal to repair yourself and you will need to get a Gas Safe registered engineer in...

dp
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Re: Gas hob problem

Postby dp » Mon Sep 16, 2013 4:31 pm

simmitc wrote:"Flame Failure Device" safety feature. You have to keep the knob pressed with the gas alight for a few seconds until it is warm enough to stay alight on its own. If 5-10 seconds doesn't work, then there is a fault.
Almost certainly this. Brilliant device, if the gas goes out for a moment, say it's blown out by wind then the device cools and cuts off the gas supply to stop the house filling with gas.

If holding the knob down after lighting isn't the answer then get a gas engineer to look at it, it's not worth taking chances

lambrettalad
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Re: Gas hob problem

Postby lambrettalad » Mon Sep 16, 2013 4:34 pm

thermocouples are a little like condensers ,some last years others two weeks
Cheers Alex
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bmcecosse
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Re: Gas hob problem

Postby bmcecosse » Mon Sep 16, 2013 4:37 pm

Thanks all - I know about the FSD - but each ring has it's own flame safety device - and all 4 are not working....which seems unlikely. The previous owner (of course!) assures us they were all working well before....... It's like getting 4 flat tyres -highly unlikely, unless some common factor was involved.......
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MarkyB
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Re: Gas hob problem

Postby MarkyB » Mon Sep 16, 2013 6:18 pm


"Once you break something you will see how it was put together"

bmcecosse
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Re: Gas hob problem

Postby bmcecosse » Mon Sep 16, 2013 6:51 pm

Yes - thanks Marky, used to change these all the time on the gas burners at work. It's the fact ALL 4 are suddenly not working that has me guessing it's a common (ie something affecting them all - not something that happens really often.. :P ) problem. Comparing to our hob at home - I notice the flame washes over the sensor rather more than seems to be happening in the flat. I'm wondering if the sensors have been pushed down during over-enthusiastic cleaning of the hob - prior to sale...... Happy to hear any other suggestions......no gas fitters in our midst??
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MarkyB
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Re: Gas hob problem

Postby MarkyB » Mon Sep 16, 2013 7:08 pm

I was going to ask "Did you take the top off for a proper look?" but a quick look at my cooker says this isn't that easy any more.
Are you sure there are temperature sensors? I only see the spark electrodes.

"Once you break something you will see how it was put together"

bmcecosse
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Re: Gas hob problem

Postby bmcecosse » Mon Sep 16, 2013 7:31 pm

Well yes, there are ignitors (spark like mad - so it can't be the coil...) sticking up through a hole in the gas spreader, and the temperature sensors round a bit - standing off the spreader slightly.....
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MarkyB
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Re: Gas hob problem

Postby MarkyB » Mon Sep 16, 2013 7:45 pm

My cooker must be too old for this health and safety stuff, I'll hang on to it!
Single point of failure does seem more likely, I'm thinking there is a common link somewhere.

"Once you break something you will see how it was put together"

brucek
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Re: Gas hob problem

Postby brucek » Mon Sep 16, 2013 8:07 pm

If the cooker lid isn't pushed fully back, then on my cannon cooker the flame won't stay lit. Also it cuts off the flame if lit when the lid is lowered. maybe that might be part of the issue? :-?


bmcecosse
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Re: Gas hob problem

Postby bmcecosse » Mon Sep 16, 2013 8:12 pm

Not sure what you mean by 'lid' - but it does suggest some sort of safety link that overrides everything.... To get at the thing is going to be a b nuisance - need to remove the oven underneath first....grrr. Going to try applying heat to the sensor from a 'chef's' gas torch - to see if that keeps the flame going.
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MarkyB
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Re: Gas hob problem

Postby MarkyB » Mon Sep 16, 2013 8:29 pm

Good call brucek, my aged Zanussi still has a lid and there is a button at the back that disables things.
If the lid itself is long gone, it's glass after all, there may also be a button or some hidden mechanism that relies on the hinges being in the up position.

"Once you break something you will see how it was put together"

brucek
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Re: Gas hob problem

Postby brucek » Mon Sep 16, 2013 8:30 pm

Aah - sounds like a different sort of arrangement then Roy. Mine has a glass lid that covers the rings when not in use so you can use it as a work surface. Good luck in finding the fault! :wink:


bmcecosse
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Re: Gas hob problem

Postby bmcecosse » Mon Sep 16, 2013 9:23 pm

I understand - and it's interesting that it can be connected in a way to cut off the flames!
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kennatt
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Re: Gas hob problem

Postby kennatt » Tue Sep 17, 2013 7:48 am

Roy could it be that each sensor is linked.so that if all gas rings are burning,if one blows out then they all shut off as a safety feature

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Re: Gas hob problem

Postby bmcecosse » Tue Sep 17, 2013 8:52 pm

I believe that can be the situation on some hobs- but as it turns out, not here. I solved it for now. I saw that the flames were barely touching the tips of the sensors (and the sensors are very firmly held where they are..) - and I also noticed that in the past - someone had slightly deepened the extra groove in each of the aluminium flame distributors, pointing towards the sensor - to try to allow a better flame to impinge on the sensors.... So - I deepened the grooves further with a hacksaw blade - and Bingo - they all work now, and yes - they still cut the gas if the flame is extinguished. I have no idea why I had to do this - the gas pressure appears to be ok, giving good heat at each burner... We will probably fit a new hob in the near future, but at least it's working for now! Thanks all for your interest, it really does help to be able to 'talk' to others about problems like this ! Roy
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Re: Gas hob problem

Postby irmscher » Thu Sep 19, 2013 12:06 pm

Roy I hope you have a carbon monoxide meter fitted in the room just to be on the safe side :D


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