Gas Hob problems

[mangocrazy]

About 9 months ago I bought a gas hob that could run on natural gas or LPG, and took it down to the moeypit in France. It was fitted into the worktop last October and I made the final connections between gas bottle and hob when I was down there last month. The bottle was a 3/4 full one that we'd been using previously on a freestanding cooker and the regulator was similarly a known good one.

Having connected the hob to the bottle, I turned on one of the burners and hit the ignition button. Nothing, rien, zilch, nada. I tested the connection with a hand-held gas leak tester and not only was there no leakage from the hob to bottle joint, there was clearly no gas being emitted from any of the burners.

I disconnected the bottle from the hob, fired up my portable compressor and shoved the blowy nozzle (technical term) up the inlet elbow, switched all the burners to full and gave it a dose of compressed air. No air came out of any of the burners.

I even undid one of the jets, switched all but that burner off and tried again. No disturbance in the Force could be felt.

So - what could be blocking the passage of air/gas from the inlet to the burners? Do new gas hobs come with a blanking plate installed that needs to be removed? Or could it be a malfunction with the flame failure security device that is shutting down the supply at some point? Or is the hob kust plain faulty?

Any suggestions/ideas/hints/tips gratefully received...

 

[Cobbler]

Just a thought, you are holding the knob down to disable the thermocouple until the flame heats it up?

 

[CompoSimmonite]

Does the hob have a glass top that comes down to cover the burners when they are off ? Such tops have a valve to cut off gas if burners left on.

 

[Kayos]

Sounds like the fsd isn't opening, usually press knob as you turn it, they can fail but are individual to each burner so can't see 4 going

 

[mangocrazy]

This is a picture of the hob in question.

I pressed down on the knob(s) for several seconds when trying to ignite them. Nothing happened. No ignition occurred at all.

 

[Ton-up]

Does it need mains power, have you plugged it in?

 

[500e]

Our glass\gas hob will work without leccy & there is no gas thermocouple on any ring not really feasible with Pietro press lighter you are not going to stand holding the button down for every ring

 

[Crater Creator]

Have you maybe kinked the hose when lowering the hob into place?

 

[mangocrazy]

The piezo ignition does require mains ignition and this is available and working. The connection to the hob is by rigid 10mm copper pipe, which then converts to normal flexi hose at the bottle. The 10mm copper pipework flows gas (proven by my tester and also by compressed air). Everything tells me that the blockage (whatever it is) exists between the gas inlet and the burners. And I've tried every burner and none of them emit gas (or compressed air).

 

[rtbcomp]

Is there a safety trip. like on a motor, that needs resetting? May have got tripped in transit? On/off tap between the inlet and the burners?

 

[mangocrazy]

Yes, I was wondering about an on/off tap in line or a safety trip. The only problem is the hob is installed into the worktop and the metal undertray would need to come off to check, which will be tricky. I have a suspicion that the hob will need to come out of its aperture to check properly, which means I'll have to remove the sealant between worktop and hob that I applied so carefully...

 

[Rig Pig]

You haven't left a plastic plug in the supply line?

 

[mangocrazy]

You haven't left a plastic plug in the supply line?

That would just be too obvious, wouldn't it... ? Can't check right now, as I'm best part of 1000 miles away, but it's one of the things I'll be checking when i go back.

 

[WorkshopChris]

That would just be too obvious, wouldn't it... ? Can't check right now, as I'm best part of 1000 miles away, but it's one of the things I'll be checking when i go back.

Ok lets hope you post back to this thread with a positive outcome as opposed to a post in http://www.mig-welding.co.uk/forum/threads/the-confessional.72607/ about how you once left a plastic blanking plug in place.
Is it much of a pipe run once you sort the problem, i used to rent out holiday caravans and the first time at the start of the season it used to feel like hours before the gas would come through and fill the line to finally light.

 

[mangocrazy]

Yes, I fervently hope I don't have to enter the confessional in a few month's time...

The kitchen is on the first floor and the gas bottle is on the floor below in the garage. 10mm copper pipe goes straight up the garage wall, through the floor and into the back of the kitchen cabinet, and then into the hob. Probably 9-10 foot run of 10mm pipe. With everything connected, i opened the gas bottle, went upstairs and just cracked the gas union open a touch, and my gas testing probe went apesh1t. So gas was definitely getting through.

 

[Tigman]

I always thought you had to change the nozzles for LPG , sure Ive seen a little bag containing the nozzles I could be wrong !

 

[mangocrazy]

Yeah, the hob came with a set of LPG jets to replace the natural gas ones. One of the first jobs I did on it.

 

[Tigman]

Generally they ignite and you have to hold the knob down for a few seconds then it will stay alight , certainly sounds like the gas aint getting through !

 

[colnerov]

Hi, How cold is it down in the garage? If it's too cold it may not be gassing sufficiently and LPG being heavier than air may not be able to rise easily.

Colin

 

[mangocrazy]

It was reasonably warm while I was there. Outside temps were in the low to mid 20s C, and inside was probably 4 or 5 degrees lower, so doubt the temps would be an issue. Also the LPG canister is pressurised to around 13 bar from memory. so I think it should have sufficient heft to propel it up one floor. My gas tester confirmed that the gas was reaching the union with the hob.