Gas oven and grill issue

[rustypaperclip]

Hi there,

 

I have a gas water heater, hob and gas oven and grill. 

 

The issue I am having is that when I push in the knob and light the oven, it only stays lit if I keep the knob pressed.

 

When the knob is depressed, the flame goes out. Same with the grill. Only when I keep it pressed for a few minutes does the oven stay lit. It used to light and stay lit instantly but not now.  

No issue lighting my hob or water heater. 

 

Why might this be? And how to rectify it? Any pointers much appreciated. Thanks. 

[Tony Brooks]

The flame failure probe is not in the oven gas flame, because the relevant burner "jet" is blocked, the burner is is displaced, or the probe is displaced.

 

You do need to keep the knob pressed in for a few seconds.

 

Edited July 6 by Tony Brooks

[rustypaperclip]

31 minutes ago, Tony Brooks said:

The flame failure probe is not in the oven gas flame, because the relevant burner "jet" is blocked, the burner is is displaced, or the probe is displaced.

 

You do need to keep the knob pressed in for a few seconds.

 

Not sure I understand. Are you saying it might be that the burner is displaced or the probe is? How would I get it out of being displaced? Is it case of repositioning it?

 

Its more than a few seconds, upwards of minutes and sometimes it still doesn't stay lit.  

 

 

[LadyG]

Try a soft toothbrush and a torch. Keep the area clean using a dustbuster vacuum if necessary. 

Pipecleaners may be used to clear the jets, but are not always readily available.

Edited July 6 by LadyG

[nicknorman]

There are a few possible different technologies for flame failure detection, one is a thermocouple that gets heated, a small voltage is produced that keeps the gas valve open. It takes a few seconds for the thing to be heated enough. If the flame isn’t really playing on the probe, or the probe is generally “tired” then it can be slow or malfunction. As mentioned, if the flame isn’t playing on the probe this is usually because something is upsetting the flow of gas and/or air. Dirt or corrosion in the jet and burner.

 

Another technology is a flame conductivity check - an electrode is bathed in the flame which also reaches the metal of the burner. The flame is a plasma which is highly conductive and the system detects low resistance and keeps the gas valve open. This type of system needs a power supply (battery or supply from the boat) , whereas the first I mentioned doesn’t. The latter generally uses the sparking (lighting) electrode as the flame probe, and the flame shape is more critical than the thermocouple as the flame has to touch both the electrode and the burner metal. But again, dirt and corrosion in the jet and burner are usually at the root of the problem.

[Tony Brooks]

And we won't have a chance of guessing which one or to answer the questions is we don't know the cooler's make and model.

[rustypaperclip]

3 minutes ago, Tony Brooks said:

And we won't have a chance of guessing which one or to answer the questions is we don't know the cooler's make and model.

It's a Thetford duplex 

[Tony Brooks]

1 hour ago, rustypaperclip said:

It's a Thetford duplex 

 

This may help you located and inspect the suspect area. the probe is marked as 11, and it is a convectional thermocouple.

 

https://www.thetford.com/app/uploads/2024/07/SPL-Oven-MK3-SOV70XXX.pdf

 

More info, it seems they may have changed from thermocouple to flame conductivity  depending on when built, so you may need to find the model and serial numbers.

Edited July 6 by Tony Brooks