Dirty burners?

[acropolis22]

The gas hob works fine. The gas oven works fine. The grill lights, but goes out when you let go of the button, however long you leave it. What would cause this? Is it likely that only the grill burners need cleaning? I've no idea what other causes there might be.

 

[poppycamper]

The safety thermocouple will be duff/needing adjusted.
It sees flame and stops gas flow if it doesn't...

 

[Lenny HB]

Agree probably the thermocouple.

 

[Ninjabob]

I thought this was another "nasty diesels" thread

 

[acropolis22]

The safety thermocouple will be duff/needing adjusted.
It sees flame and stops gas flow if it doesn't...

So it thinks there is no flame when there is?

^{_{Subscribers  do not see these advertisements}}

 

[poppycamper]

So it thinks there is no flame when there is?

Exactly.... if it does not think there is a flame it turns off gas so it does not continue to flow and filling your van with gas just waiting for a spark to make a big BOOM .
When you hold in knob when lighting burner you are overriding safety device until flame is lit.

 

[dunnah01]

Try removing the grill knob and putting a bit of card into the socket to move the knob a bit further away from the facia plate. This allows the button to push the valve bit further to register the flame

 

[acropolis22]

Try removing the grill knob and putting a bit of card into the socket to move the knob a bit further away from the facia plate. This allows the button to push the valve bit further to register the flame

Could it be that easy?

 

[acropolis22]

Exactly.... if it does not think there is a flame it turns off gas so it does not continue to flow and filling your van with gas just waiting for a spark to make a big BOOM .
When you hold in knob when lighting burner you are overriding safety device until flame is lit.

So, is changing/adjusting the thermocouple a DIY job?

 

[dunnah01]

Could it be that easy?

Always works on mine - a bit of fiddling to get the knob packed enough but a simple fix (usually)

^{_{Subscribers  do not see these advertisements}}

 

[dunnah01]

Without getting to close to innuendo it is often possible to just get your fingers behind the knob to prise it away a little bit. If there is enough friction between the knob and shaft then it often does the trick and keeps the flame lit.

 

[poppycamper]

I would first check that you have not knocked thermocouple out of position....possibly with grill pan.. It should sit in the flame and when flame is burning thermocouple should glow cherry red.

 

[airwave]

Seriously speaking , i've never come across a dirty burner , and i have some quite old burners , so i would also plumb for the thermocouple . It's by far the most common fault with cookers , ovens , heaters , and in particular fridges , is the thermocouple .

Personally , i would replace the thermocouple , unless it's some fancy bit of kit it's both relatively easy , and cheap before , i started bending or adjusting anything else .

 

[dunnah01]

I baulked at replacing the thermocouple on my hob. Getting the hob out with all the gas disconnections and space limitations was going to be a right PITA. A good clean up of the bits I could reach underneath after partial removal did the trick. I think just taking the knobs off and putting them back would have done the same tbh but all still fine after 12+ months of use.

 

[helzie2020]

The gas hob works fine. The gas oven works fine. The grill lights, but goes out when you let go of the button, however long you leave it. What would cause this? Is it likely that only the grill burners need cleaning? I've no idea what other causes there might be.

We have this from time to time on our gas hob in the van.

Last time it happened, I could see that some of the jets were lighting a bit more slowly than the others so I just cleaned around the jets with a dishwashing brush and that fixed the problem.

^{_{Subscribers  do not see these advertisements}}

 

[G-RMPS]

I baulked at replacing the thermocouple on my hob. Getting the hob out with all the gas disconnections and space limitations was going to be a right PITA. A good clean up of the bits I could reach underneath after partial removal did the trick. I think just taking the knobs off and putting them back would have done the same tbh but all still fine after 12+ months of use.

Similarly, I reach behind the offending knob and push the wires towards the knob. Seems to work for us.

 

[acropolis22]

Thanks everyone for your suggestions. I'm going to have a good look at the workings tomorrow in daylight. I'm a bit confused about some of the ideas. What exactly are we trying to do by fiddling with the knob? This is nothing to do with the thermocouple suggestion is it?

 

[Manic]

The burners on my Smev hob sometimes don’t work well and have to remove the burner top plate and remove the rust.

 

[dunnah01]

Thanks everyone for your suggestions. I'm going to have a good look at the workings tomorrow in daylight. I'm a bit confused about some of the ideas. What exactly are we trying to do by fiddling with the knob? This is nothing to do with the thermocouple suggestion is it?

It's somehow linked to the safety valve and ensures that the load signal from the thermocouple is sufficient to ensure gas only flows if there is a flame. I'm no gas engineer but presumably the valve's internal switch has a better contact if pushed a bit further with the knob.

 

[acropolis22]

It's somehow linked to the safety valve and ensures that the load signal from the thermocouple is sufficient to ensure gas only flows if there is a flame. I'm no gas engineer but presumably the valve's internal switch has a better contact if pushed a bit further with the knob.

Presumably I could check to see if the "knob" suggestions will work by taking the knob off and holding in the shaft while lighting the grill? (Apologies for the lashings of double entendres)

^{_{Subscribers  do not see these advertisements}}

 

[dunnah01]

Presumably I could check to see if the "knob" suggestions will work by taking the knob off and holding in the shaft while lighting the grill? (Apologies for the lashings of double entendres)

It's definitely worth a go before ripping everything apart (not a single double entendre was harmed in this post )

 

[Googlebot]

I had 7 new thermocouples fitted (yes 7) under warranty by Cosford Caravans. It was just out of warranty when it wouldn’t light again.

A mate I used to Labour for who is a Gas Fitter told me to get some pliers and bend the metal bracket holding the thermocouple so that it pushed it right at the hottest part of the flame. I was reluctant as it seemed a bit extreme. The bracket was built into the back of the grill and took some bending!

Guess what? Worked a treat ever since and was fine when I sold the van.

 

[acropolis22]

Ok, this is getting silly now. I tried doing what Googlebot suggested before he suggested it, about an hour ago. I tried to bend the bracket with my fingers and it felt like it wouldn't move. However, I just tried to light the grill and it worked fine. Could some tiny movement in the bracket have cured the problem? I will try again tomorrow. I may be back....

 

[jockaneezer]

There are two types of thermocouple in common use, one is a "capillary tube" type in which the contents of (a usually copper) tube expand on heating and this expansion pushes on the flame failure device, holding it open to allow the burner to operate. The other type is electrical and usually has a porcelain insulated section with a metal rod poking out into the flame, on heating this this up, it generates a miniscule electric current which is sufficient to hold open the flame failure valve and allows gas to the burner.
On our Smev hob, I've had to pull off the connector to the knob and refit it after cleaning off any tarnish to get it to stay lit. Because the voltage is so low, it doesn't need much contamination to stop it operating.
Also, as others havevmentioned, whatever type is fitted, the flame must impinge on it directly.

 

[Googlebot]

Ok, this is getting silly now. I tried doing what Googlebot suggested before he suggested it, about an hour ago. I tried to bend the bracket with my fingers and it felt like it wouldn't move. However, I just tried to light the grill and it worked fine. Could some tiny movement in the bracket have cured the problem? I will try again tomorrow. I may be back....

Yes, it could. They can be very picky about the part of the flame they need to be in.

^{_{Subscribers  do not see these advertisements}}

 

[plumbob]

There are normally two types of flame failure devices one a thermocouple and the other flame rectification device. Have A look in once you have pressed in control knob and ignition and check if thermocouple is enveloped by flame if it is thermocouple is possibly u/s but it could be loose where it connects to solenoid
Tom

 

[plumbob]

The other thing you need to look for is the thermocouple in the burner flame or separate pilot flame if so you may need to check the pilot injector.
if I can help at all I’ll try
Ex self employed gas fitter natural and calor for 40 years
One thing you should be aware of is if you have to break a gas joint should use a Gas safety registered installer

 

[plumbob]

After reading all posts if your bending the bracket to get the pilot to envelop the thermocouple it generally means dirty pilot injector dirty or blocked

 

[acropolis22]

It seems OK now, having tested again twice. I bent the thermocouple, but it felt as though it hardly moved. Very stiff. But it seems to have worked.......

 

[mitzimad]

There are two types of thermocouple in common use, one is a "capillary tube" type in which the contents of (a usually copper) tube expand on heating and this expansion pushes on the flame failure device, holding it open to allow the burner to operate. The other type is electrical and usually has a porcelain insulated section with a metal rod poking out into the flame, on heating this this up, it generates a miniscule electric current which is sufficient to hold open the flame failure valve and allows gas to the burner.
On our Smev hob, I've had to pull off the connector to the knob and refit it after cleaning off any tarnish to get it to stay lit. Because the voltage is so low, it doesn't need much contamination to stop it operating.
Also, as others havevmentioned, whatever type is fitted, the flame must impinge on it directly.

Your not quite right there jock the small copper tube type contain to different
Metals which when heated produce a current to hold a valve open with an electro magnetic there's no capillary involved .you maybe getting confused with an oven thermostat which is capillary operated
The second type with the pin and ceramic is flame rectification which is fed a current travels across the flame to ground and tells the electronics there is a flame
I hope you don't think I'm correcting you for the sake of it I know from what you've shown on here you a very capable engineer and I hope to inform