Gas cooker oven working operation?

[paulpeters]

Hi, i am not sure if this is the correct place to ask this question but I have been trying to find out an answer with no joy.

I have a gas cooker, oldish type but works well, and am just trying to work out how it actually works, like the operating of it.

When I turn the dial for the oven, i then hold in the spark switch for a second or so and on releasing it the oven lights. After about 20-30 seconds it lights fully (the flame gets bigger) and all is well.

My question is how does the gas get down to the burner, is it via the dial when i push it in and turn it clockwise, eg to gas mark 5? I have read in a book that oven burners's in gas cookers have a bypass hole, but i do not understand what this does? WHat is the point of the bypass hole?

Is the thermostat to the oven linked behind the oven's gas dial as well?

If anyone can help me understand how it works i'd be very grateful.

 

[powell30]

Whats so interesting about your oven's working? As for bypass i am just not convinced this is just an innocent question.

Gas work by diyers is not something i would recomend therefore i won't help. Others will have to make a judgement call as to your motives.

 

[paulpeters]

I'm just curious how it works/lghts... and what a bypass does. My cooker's been serviced and I have a landlord certificate for it. Was just trying to learn.

 

[glasgowgas]

post it in the infamous Combustion Chamber and all your answers will be revealed

 

[macfudd]

The bypass comes into action when the temperature in the oven reaches that set by the thermostat.It allows a small amout of gas through to the burner to keep the burner alight and the temp steady.

 

[Legion]

Hi, i am not sure if this is the correct place to ask this question but I have been trying to find out an answer with no joy.

I have a gas cooker, oldish type but works well, and am just trying to work out how it actually works, like the operating of it.

When I turn the dial for the oven, i then hold in the spark switch for a second or so and on releasing it the oven lights. After about 20-30 seconds it lights fully (the flame gets bigger) and all is well.

My question is how does the gas get down to the burner, is it via the dial when i push it in and turn it clockwise, eg to gas mark 5? I have read in a book that oven burners's in gas cookers have a bypass hole, but i do not understand what this does? WHat is the point of the bypass hole?

Is the thermostat to the oven linked behind the oven's gas dial as well?

If anyone can help me understand how it works i'd be very grateful.

You have a phial and bellows type of thermostat, it depends on a liquid or vapour to open or close gas valve.The thermostat is set by a cam which is mounted at the front of the tap core, it acts on a spindle which pushes up on the valve arm.The springs on the arm, valve and spindle end of the arm ensure that any overshoot of temperature will not damage the control. As the temp rises the bellows expand and act on the centre of the arm closing the valve. When temp falls the bellows contract allowing valve to open and letting more gas to burner.The phial and bellows part of your thermostat is sealed it contains a liquid or vapour which when heated expands, the bypass ensures that when the valve is closed enough gas gets to the burner to provide a maintenance rate. The actual bypass hole is very small and can easily become blocked it is not a good idea to try and unblock with a pin etc, best to use compressed air so as not to largen the bypass hole which will increase the bypass rate and f*uck it up basically.

If you think that I know about cookers don`t be mislead I have just read out the blurb from my cooker book. if you understand any of it please get back and explain it to me because I still can`t get my head around oven thermostats. Thanks.

British gas pay subbies 5 quid to service a cooker, you now know more than any service engineer, make sure he greases yer taps missus!

 

[ChrisR]

Legion - no you don't understand, do you

I don't see any harm in explaining the principles of how they work. I wouldn't advise anyone fiddles with them at all, even gas qualified. Horrid things. Only gas engineers should replace them, and then there's a bunch of tests to do.

Right, there are two mechanisms.
Flame supervision device
You turn the knob and let a little gas through bypass #1, which gets ignited, by whatever means.
That warms up a liquid/vapour expansion thingy which opens the gas valve so the flame goes to full rate.

The thermostat is cold of course.
When the stat gets to the temp on the dial, it closes a valve, via another expansion thingy. It does it slowly, but not in a calibrated way, so think of it as closing a valve fully. The gas then has to go through bypass #2, to keep the flame alight.
When the oven cools the tstat valve starts to open, so it hovers around the right temp.
If either bypass is wrong in any way, the oven doesn't work, or you blow your house up, or burn everything in the oven. Leave the damned things alone!