Grill Thermocouple

[Meantime]

5 minutes ago, FairTmiddlin said:

Differs from my Propane Butane CORGI training then.

Its interesting because even Thomas Seebeck who discovered the effect, hence the name Seebeck effect initially believed it was due to magnetism. 

What is the Seebeck Effect?

The Seebeck effect (often misspelled as ‘Seeback effect’) is the build-up of an electric potential across a temperature gradient in different electrical conductors or semiconductors.

For example, a thermocouple measures the difference in potential across a hot and cold end for two dissimilar materials (e.g. an electrical conductor or semiconductor). The potential difference measured is proportional to the temperature difference between the hot and cold ends.

This phenomenon was discovered by German physicist Thomas Seebeck (1770-1831). Seebeck discovered this by observing a compass needle which would be deflected when a closed-loop was formed between those two different metals or semiconductors.

Seebeck initially believed that it was due to the magnetism induced by the temperature differences and he called the effect as a thermo-magnetic effect. However, Danish physicist, Hans Christian Orsted realized that it’s an electrical current that is induced, which because of Ampere law deflects the magnet.

[Vaughan]

12 minutes ago, Meantime said:

Seebeck initially believed that it was due to the magnetism induced by the temperature differences and he called the effect as a thermo-magnetic effect. However, Danish physicist, Hans Christian Orsted realized that it’s an electrical current that is induced, which because of Ampere law deflects the magnet.

Which is why I referred to the thermocouple as a solenoid.

Which is an electro-magnet.

It is also an extremely reliable, proven and fail-safe device.

[Meantime]

28 minutes ago, Vaughan said:

Which is why I referred to the thermocouple as a solenoid.

Which is an electro-magnet.

It is also an extremely reliable, proven and fail-safe device.

Although the thermocouple connects to the control valve, which contains the solenoid. They are two discrete separate components. A thermocouple does not have to be connected to a solenoid, and in the case of ovens the thermocouple is often 1300mm long. Again if the solenoid did need to be changed, that would require disturbing the gas connection, which in turn I would leave to a gas safe engineer.

[Ray]

You guys certainly know your stuff! A very interesting discussion, thank you.

From a strictly lay person point of view I've learned a lot and my main practical take is of course to proceed with caution and do nothing to disturb the gas connection.

[Meantime]

2 minutes ago, Ray said:

You guys certainly know your stuff! A very interesting discussion, thank you.

From a strictly lay person point of view I've learned a lot and my main practical take is of course to proceed with caution and do nothing to disturb the gas connection.

In the picture below the left hand copper connection is the thermocouple connection to the gas control valve. This can just be unbolted without disturbing the gas connection. In the case of your thermocouple Ray it will be a spade connection. The middle connection is the oven thermostat and as the oven heats up it will start to close the valve to regulate the gas supply to regulate the temperature. The right hand silver pipe is the gas connection. The main body contains the valve and the solenoid. As you can see from this picture to replace the solenoid would mean disconnecting the gas. However the thermocouple is fine to replace.

The picture below shows the thermocouple disconnected from the control valve. If you were to turn the oven on and hold the k.n.o.b in to defeat the flame failure valve you would be able to measure a small millivolt voltage between the copper body and the silver centre despite the thermocouple not being connected to anything supplying it with electric. It is purely the Seebeck Effect which is inducing a voltage at the cold end.