Gas cooktop failing to ignite after initial lighting

[artzend]

Thanks for that too. Mine is just a cooktop set in a bench (it's an Avan cruiseliner) so I have to take the plate out. I will go and see what the van places can offer and if they have spares. I am off on a trip shortly so don't want to be missing parts when I go. It may have to wait for a bit until I have time to sort problems.

Thanks for all the help though.

Tim

[artzend]

Hi

I have since seen that it is possible that it may be the safety magnet that is at fault, I never would have found that, but it now seems that I have two lines to follow, when I get home again, by swapping parts around.

Tim

[Old Techo]

Tim, never heard of a safety magnet

Do you mean a safety cut-out operated by the lid position?

[Wombat96]

My dometic thermocouples look accessible via the griller area. Here is a pic via a mirror.

'A' is the knob end of the copper pipe and 'B' the actual thermocouple (hidden under the knob control) where it pokes up to reach the burner.

Don't encourage them, OT.

[Old Techo]

Don't encourage them, OT.

Fair enuff.... but I'm only referring to the thermocouple connection and that is a millivolt DC electrical circuit and nothing to do with any gas plumbing or connection.

[artzend]

It was on the caravans plus website and some guy was referring to them having changed size since his was made. I haven't taken my cooktop out to see what is there yet, so have no idea if I have them or not. They made reference to the fact that these magnets can be the cause of the problem I am having. Here is the page link. http://caravansplus.com.au/catalog/prod ... ts_id=9264

I am interested to see your take on this.

Tim

[Old Techo]

Thanks Tim, I get it now

Never heard them called that but I'm not a gas appliance expert.

The way they work is the thermocouple generates a very small voltage when heated by the gas flame. Think of it as connecting a battery. This tiny voltage is not enough to operate a regular solenoid however it is enough to hold in a solenoid that has been manually actuated i.e you pushing in the knob.

What I call a solenoid others have apparently called a magnet.

Sure, this component could be faulty but I've never heard of a failure. A basic solenoid has a moving part and a coil (turns of copper wire wound in a coil) that generates a magnetic field when current flows through the coil. I imagine coil failures to be rare but maybe some mechanical aspect could stick. Dunno... complete guess in this regard

The thermocouple that generates the 'hold in' voltage is the typical failure, possibly due to being heated/cooled so many times. Thermocouples can glow red in normal operation.

[TramcarTrev]

I think your on the money there OT. If you look at them at the tip there is a little blob of metal. That's the join where the wires meet. It's that exact interface where the voltage is generated and any abuse of that interface can cause malfunction. They are usually filled with ceramic dust as an insulator if that moves or allows the wire to touch and short it's all over as well. It's an intriguing problem, I wish o was closer to pull it to bits.
For the OP I hope it's not the safety magnet they are expensive.

[artzend]

Thanks guys, I will let you know how I go when I get to it. Got a 6 week trip to Cairns and Cooktown first.

T

[dieseltojo]

Hi artzend,
Before you do get a replacement just check that the problem one is actually screwed in tight in the first place. If it is loose it might not be sending the valve open correctly.

Also check that the bit near the flame is in the flame the same as the others.