Gas Hob knobs wont stay pressed in for the gas to be released

[Belli]

Hello,
I have just bought my first second hand caravan and nothing seems to work so going through things one by one. The 3 burner gas hob which appears to have never been used (or is a new replacement) will not stay ignited. The gas comes out when I press and turn the knobs. The ignition does not work (no clicking) so I lit with a flame. But when I let go of the knob it springs back out again so cuts of the gas. I looked underneath and it is all shiny and new so no clogging of the knobs. The caravan is a Fendt Diamant 2008.

 

[Mr Grumpy]

Welcome aboard
Best advice get it looked at by your local mobile caravan engineer. Gas can be dangerous,.

 

[bertieboy1]

Hello,
I have just bought my first second hand caravan and nothing seems to work so going through things one by one. The 3 burner gas hob which appears to have never been used (or is a new replacement) will not stay ignited. The gas comes out when I press and turn the knobs. The ignition does not work (no clicking) so I lit with a flame. But when I let go of the knob it springs back out again so cuts of the gas. I looked underneath and it is all shiny and new so no clogging of the knobs. The caravan is a Fendt Diamant 2008.

Sounds like your not holding the knob in long enough after burner ignited.Let knob go when gas burner ignites after say 5secs.

 

[ProfJohnL]

Helo Belli. fo

I wonder if its case of not holding the knob in for long enough after the gas has been ignited. The knob might need to be held in for up to 10 seconds before being released. If its works try again untill you discover how long your hob needs.

If its longer than 10 seconds then some thing is potentially wrong and you should arrange to have it checked by a local professional.

 

[Jcloughie]

Hi and welcome to the forum.

Two issues, are lighting and staying alight.

To light, sparks are generated by a piezoelectric source which may be powered by the caravan battery or a dry cell battery. To work, the tip near the burner needs to have a small spark gap. If too big or too small it will not operate.

To stay alight, a sensor is located in the flame, this is connected to a control that turns the gas on. This is called a thermocouple. They are cheap and easy to fit without disturbing gas connections. But often very difficult to get to.

John

 

[ProfJohnL]

To light, sparks are generated by a piezoelectric source which may be powered by the caravan battery or a dry cell battery. ...

FYI:-

Most modern hobs do use a an electronic spark ignitor which is battery powered.

However this is not a Piezo ignitor. Piezo are a crystal lattice which if stressed will produce a voltage across the lattice. If struck hard enough the voltage is sufficient to cause a spark capable of igniting a gas flame. Piezo ignitors are usually manually operated.

 

[Belli]

Sounds like your not holding the knob in long enough after burner ignited.Let knob go when gas burner ignites after say 5secs.

Thank you. I will give that a try.

 

[Belli]

Helo Belli. fo

I wonder if its case of not holding the knob in for long enough after the gas has been ignited. The knob might need to be held in for up to 10 seconds before being released. If its works try again untill you discover how long your hob needs.

If its longer than 10 seconds then some thing is potentially wrong and you should arrange to have it checked by a local professional.

O.K Thank You. I will try that.

 

[Belli]

Hi and welcome to the forum.

Two issues, are lighting and staying alight.

To light, sparks are generated by a piezoelectric source which may be powered by the caravan battery or a dry cell battery. To work, the tip near the burner needs to have a small spark gap. If too big or too small it will not operate.

To stay alight, a sensor is located in the flame, this is connected to a control that turns the gas on. This is called a thermocouple. They are cheap and easy to fit without disturbing gas connections. But often very difficult to get to.

John

Thanks John. So far I haven't found the battery so I will connect to the car to see if the ignition spark will work.

 

[Buckman]

Does the Fendt have a 12v battery as it may be like the Hobby caravan where the battery is an extra?

 

[Belli]

Does the Fendt have a 12v battery as it may be like the Hobby caravan where the battery is an extra?

I have not found a battery but I did find a reducer which I think converts the 230v into 12v. One of the fuses has blown so I will replace that and see what happens.

 

[Mel]

Thanks John. So far I haven't found the battery so I will connect to the car to see if the ignition spark will work.

I might be wrong but I don’t think that connecting to the car ( if you mean hitching the van to the car) will work the ignition on the cooker.
mel

 

[bertieboy1]

Hi and welcome to the forum.

Two issues, are lighting and staying alight.

To light, sparks are generated by a piezoelectric source which may be powered by the caravan battery or a dry cell battery. To work, the tip near the burner needs to have a small spark gap. If too big or too small it will not operate.

To stay alight, a sensor is located in the flame, this is connected to a control that turns the gas on. This is called a thermocouple. They are cheap and easy to fit without disturbing gas connections. But often very difficult to get to.

John

Piezo needs no external electrical supply

 

[bertieboy1]

I have not found a battery but I did find a reducer which I think converts the 230v into 12v. One of the fuses has blown so I will replace that and see what happens.

Something that changes 230v ac to 12V dc is a transformer/rectifier not a reducer.

 

[ProfJohnL]

Hi Belli,

It seems you have two faults, the first is the spark ignition system does not seem to be working, and secondly the Flame Failure Device/system (FFD) is not holding the gas valve open when a flame has been established.

We are working blind here, as you may have gathered, your caravan is a continental brand, and as far as I know they haven't been manufactured for the UK market so they may not have all the same safety interlocks as UK models. We also do not know which models of appliances you have, so again we can't know if our comments are actually fully relevant regarding where the power for the hob ignitor comes from.

Some hobs may have a manually operated piezo ignitor ( push it in until it clunks which should produce one spark, and you may need to repeat the process a number of times) or whether you have a 12V operated ignitor which takes its power from the caravans battery, or whether it has its own battery pack.

As Mel has suggested if it is wired in accordance with UK guidance, then the caravan might have a "habitation" relay, which isolates all the normal 12V items from the caravans 12V supply when the car is connected to prevent them accidentally being left turned on when you tow the caravan.

Perhaps if you could post some pictures of the hob we might be able to identify it.

It would be helpful to us to know if any of the suggestions we have made have been of any help.

 

[Buckman]

Despite all the excellent suggestions, I would strongly recommend that you get a qualified AWS technician to service the caravan and repair any issues. They will be able to advsie you regarding any issues. Have you checked the age of the tyres?

 

[Hutch]

My gas hob requires the electrics master switch to be ON to get the gas to light using a spark, at each gas ring.

 

[Belli]

Hi Belli,

It seems you have two faults, the first is the spark ignition system does not seem to be working, and secondly the Flame Failure Device/system (FFD) is not holding the gas valve open when a flame has been established.

We are working blind here, as you may have gathered, your caravan is a continental brand, and as far as I know they haven't been manufactured for the UK market so they may not have all the same safety interlocks as UK models. We also do not know which models of appliances you have, so again we can't know if our comments are actually fully relevant regarding where the power for the hob ignitor comes from.

Some hobs may have a manually operated piezo ignitor ( push it in until it clunks which should produce one spark, and you may need to repeat the process a number of times) or whether you have a 12V operated ignitor which takes its power from the caravans battery, or whether it has its own battery pack.

As Mel has suggested if it is wired in accordance with UK guidance, then the caravan might have a "habitation" relay, which isolates all the normal 12V items from the caravans 12V supply when the car is connected to prevent them accidentally being left turned on when you tow the caravan.

Perhaps if you could post some pictures of the hob we might be able to identify it.

It would be helpful to us to know if any of the suggestions we have made have been of any help.

Hi,
I finally managed to test out the previous ideas (could not do it earlier) and even holding in the button for 30 seconds does not help. It will not stay in when I let go so cutting off the gas. Also there is no clicking sound when I push in the button. Gas comes out but no ignition 'click' So I have to light the flame with a lighter. But non of that helps as the button won't stay in. I have also noticed there is nothing I can see that connects the hob to electricity. No leads or battery. I am presuming there needs to be an electrical feed. I will take some photos. Thank You

 

[Belli]

My gas hob requires the electrics master switch to be ON to get the gas to light using a spark, at each gas ring.

I can't find and electrical source connected to the rings.

 

[ProfJohnL]

This is now clearly a job for a qualified technician,

 

[bertieboy1]

Hi,
I finally managed to test out the previous ideas (could not do it earlier) and even holding in the button for 30 seconds does not help. It will not stay in when I let go so cutting off the gas. Also there is no clicking sound when I push in the button. Gas comes out but no ignition 'click' So I have to light the flame with a lighter. But non of that helps as the button won't stay in. I have also noticed there is nothing I can see that connects the hob to electricity. No leads or battery. I am presuming there needs to be an electrical feed. I will take some photos. Thank You

Sometimes there is a second switch that controls the ignition and you need two hands to light a burner.

 

[ProfJohnL]

Sometimes there is a second switch that controls the ignition and you need two hands to light a burner.

You could be correct, Some older hobs used a manual piezo ignitor and that would need two hands but regardless of whether i's one or two handed job, the fact once a flame has been established even after 30 seconds of keeping the gas valve pushed in to keep the gas burning the flame failure system should hold the valve open. So there is definately some fault with the system.