Gas hob numptyness rating

[Dr Bob]

16 minutes ago, Arthur Marshall said:

The problem has changed. The initial one was that it went click but didn't light. Now it lights but won't stay lit. 

 

Well no. In my defence I am a muppet......but in the OP I said I couldnt light the stove. That was a factual statement. Everytime I tried to light it, I failed to do that ......ie a gas hob with a sustained flame. Mrs Bob could.

I do admit it took until post 20 until I fully explained the situation that it was lighting but then going out and it was the going out that is a problem.

I think only needing 20 posts to fully understand what the technical issue is (on a highly complex and mind bogglingly instructive topic such as this) is pretty good for this forum. Dont you think so?

[Dr Bob]

15 minutes ago, Boater Sam said:

What delusions?

Its Bob that is deluded, he can't see the blue flame, is he colour blind? Its a Quantum Field problem caused by the Higgs Boson field which is throughout the universe. Either that or he needs an exorcist.

Roland and I rule OK? For god's sake don't argue with us.

Com'on Sam, I was getting quite excited with your analysis of flame suppression voltage rise and if that could vary person to person.

Is the higher (or lower) capacitance of my fingers reducing the voltage in the thermocouple. Still thinking then it is a faulty 'earth' (sorry Tony) on the thermocouple. I guess the tea towel (which was dry by the way) must reduce the capacitance so my fingers are increasing the capcitance compared to Mrs Bob.

[roland elsdon]

Ive met Dr Bob . he’s  met Dr S otherwise known as Mrs E.

Im the sane one trust me I was a professional.

 

they are letting me out of here in 28 days. Just in time to Brexit.

 

[Boater Sam]

I will be back for the 29th March too. Sane and sunned.

My project after convincing Bob that its sod all to do with capacitance or him stealing voltage is to close the ENGLISH channel and install a toll, free to UK shipping, Hell of a cost to everyone else. It will make the North Sea Oil Boom look like a shove  Ha'penny game.

[magpie patrick]

1 minute ago, Boater Sam said:

I will be back for the 29th March too. Sane and sunned.

My project after convincing Bob that its sod all to do with capacitance or him stealing voltage is to close the ENGLISH channel and install a toll, free to UK shipping, Hell of a cost to everyone else. It will make the North Sea Oil Boom look like a shove  Ha'penny game.

But how does that help Dr Bob get his stove to stay alight?

[ditchcrawler]

5 hours ago, Boater Sam said:

Gas ignition is not an issue.  The spark ignites the gas OK.

 

The flame on the burner has to impinge on the thermocouple tip, which generates a small voltage. This voltage is sufficient to hold on the solenoid in the gas valve to keep the port open and allow full gas flow.

 

 But the solenoid has to be held all the way down by the action on the knob long enough for this voltage to be generated.

 

It is pressing the knob IN THE CORRECT POSITION that opens the gas valve initially and closes the solenoid mechanically.

The knob should be turned to the full flame position and held fully down for a few seconds to enable the thermocouple to heat, the solenoid will then hold the valve open when the knob is released maintaining gas flow. The control of the flame size can then be adjusted.

I suspect that you have turned the knob but not to the correct position. When you cover it with a cloth you cannot see the markings and you then hold it BY CHANCE in the correct position.

 

Body capacitance, luck, static and sex have nothing to do with it. Its dumb, it just works, it doesn't know why.

now you have spoilt it talking common sense 

[Boater Sam]

Oh, I can't be bothered about that now, much more important things to do.

Besides its not what he thinks, its finger trouble, digital inaccuracy.

[roland elsdon]

He hasnt posted. Its working. Soundtherapy worked

[Dr Bob]

1 hour ago, roland elsdon said:

He hasnt posted. Its working. Soundtherapy worked

Pardon?

[IanD]

Barefoot vs. socks/slippers could be a clue. Does it work for you if you're barefoot (like Mrs. Bob)? Does it work for Mrs. Bob if she's wearing slippers/socks (like you)?

[WotEver]

Is the cooker fed with mains or 12V? If mains then check the earth. If 12V then check the -ve return. If neither (internal battery) then I have no suggestions. 

[Dr Bob]

1 hour ago, WotEver said:

Is the cooker fed with mains or 12V? If mains then check the earth. If 12V then check the -ve return. If neither (internal battery) then I have no suggestions. 

It is fed with 12V. Problem is I cant see easy access to the hob.

It is this one - just less than 2 years old - but used 80% of the year as a liveaboard

.

https://www.grasshopperleisure.co.uk/thetford-topline-931-series-3-burner-hob-black-16159-p.asp

Without seriously dismantling the kitchen, I'm not sure I can see the -ve wire from the hob and no idea where it comes back to the common -ve at the back of the boat.

The iginiter circuit works fine with a good strong spark, spark, spark at the press of the knob which sounds strong even when the Nesspresso machine is taking 130A out of the batteries (660Ahr in good nick) and always lights the gas instantly. I always try to light it now with no other loads/pumps running. I dont think it is the flame surpressor thermostats as it is the same on all 3 burners but it could be their common -ve return (I keep wanting to type 'earth'!).

The problem has gone away now that I need to turn it with my jumper or cloth between me and the knob, so everyone including the duck is happy ......but WTF is it happening?

 

 

1 hour ago, IanD said:

Barefoot vs. socks/slippers could be a clue. Does it work for you if you're barefoot (like Mrs. Bob)? Does it work for Mrs. Bob if she's wearing slippers/socks (like you)?

No, as I said a few posts ago, Mrs Bob still gets it to stay lit with socks on.

Edited February 25, 2019 by Dr Bob

[Dr Bob]

This is getting a bit ridiculous isnt it?

60 posts and I'm still non the wiser about keeping it up (the flame that is)

I bet Rusty will be along soon with the answer........although I'm not sure if he has a knob.

[WotEver]

12 minutes ago, Dr Bob said:

The iginiter circuit works fine with a good strong spark, spark, spark at the press of the knob which sounds strong even when the Nesspresso machine is taking 130A out of the batteries

Our gas fire at home does the same with the igniter fed by a D cell, so that doesn’t necessarily prove a good connection. 

[tree monkey]

15 minutes ago, Dr Bob said:

This is getting a bit ridiculous isnt it?

60 posts and I'm still non the wiser about keeping it up (the flame that is)

I bet Rusty will be along soon with the answer........although I'm not sure if he has a knob.

Do you enjoy the fresh air more than the lovely Mrs Bob, are you in the habit of opening windows or side hatch to view the new day whilst seeing to the other half desires?

[Dr Bob]

9 minutes ago, WotEver said:

Our gas fire at home does the same with the igniter fed by a D cell, so that doesn’t necessarily prove a good connection. 

...so, any more thoughts. How would capacitance affect a dc circuit. My only experience is with them as LC circuits in AC radio matching circuits.

4 minutes ago, tree monkey said:

Do you enjoy the fresh air more than the lovely Mrs Bob, are you in the habit of opening windows or side hatch to view the new day whilst seeing to the other half desires?

No, it certainly isnt to do with wind. How did you know she is lovely? I smell a rat duck.

[system 4-50]

Devices that only work for some people and not others are called Eco devices, as in EcoF**s.  Perhaps you have an EcoKnob.

Edit: This does not apply to everything. For example an Economist is a person whose utterances do not work for anybody.

Edited February 25, 2019 by system 4-50

[WotEver]

53 minutes ago, Dr Bob said:

How would capacitance affect a dc circuit. 

It wouldn’t, under the circumstances you describe. A capacitor in a D.C. circuit can be  considered as a tiny battery. Put 12V across a capacitor and then remove the voltage and the capacitor will be charged up to 12V. Put an oscilloscope across the terminals and you’ll see that 12V which will rapidly decay to zero as it discharged into the scope’s circuitry. 

 

The voltage from a thermocouple is tiny, well less than a volt, so any problem with the circuit between the thermocouple and the valve which it holds open doesn’t need to be very great. I honestly can’t imagine what your problem could be, so I’m simply suggesting simple things to check. 

 

Edited February 25, 2019 by WotEver
Clarity

[philjw]

6 minutes ago, WotEver said:

The voltage from a thermocouple is tiny, well less than a volt, so any problem with the circuit between the thermocouple and the valve which it holds open doesn’t need to be very great. I honestly can’t imagine what your problem could be, so I’m simply suggesting simple things to check. 

Agreed.  There is a fix on the Alde Comfort boiler which involves tightening the nut holding the overheat thermostat so that it will stay alight.
Doesn't explain the tea towel fix though.

[tree monkey]

1 hour ago, Dr Bob said:

...so, any more thoughts. How would capacitance affect a dc circuit. My only experience is with them as LC circuits in AC radio matching circuits.

No, it certainly isnt to do with wind. How did you know she is lovely? I smell a rat duck.

The duck sends positive reports.

 

Do you eat a lot of windy food?