Hi gents

Thermopile and a flame switch and a piezo igniter used on the burner assembly.
The pilot is lit all the time ,but the burner does not light up .
How do I measure the millivolt to make sure the thermopile is OK??
How do I check out the flame switch to make sure it is not faulty>??
Any response will be appreciated .

You need a volt meter to check voltage and millivolts is so low of voltage that you can not check it with a regular volt meter. If you have a regular volt meter with an amp probe on it I can tell you how to check the amps and that would indicate that there is voltage.

So let me know if you have one.

The biggest problem with a millivolt system is that the pilot is not burning good or the valve is bad.

You need a volt meter to check voltage and millivolts is so low of voltage that you can not check it with a regular volt meter. If you have a regular volt meter with an amp probe on it I can tell you how to check the amps and that would indicate that there is voltage.

So let me know if you have one.

The biggest problem with a millivolt system is that the pilot is not burning good or the valve is bad.

Thanks for your response . Yes I do have a clamp on amp .
Would appreciate if you would please show me how to check the amps to make sure there is any voltage and also I would like to know how to check the flame switch on a F/P as well as how to check a thermocoupl too . Tks again
Looking forward to your response .

Take a length of small wire with a cover Wrap it ten wraps around one of the clamps of the amp meter, set the meter at the lowest amp reading. Not disconnect one of the wires on the valve, touch one end of the wire that you wrapped around the meter to the post that you disconnected the wire from, touch the other end of the wrapped wire to the wire that you disconnected from the valve. The meter should read some amperage if the power is going through the valve.

Let me know if this works.

Take a length of small wire with a cover Wrap it ten wraps around one of the clamps of the amp meter, set the meter at the lowest amp reading. Not disconnect one of the wires on the valve, touch one end of the wire that you wrapped around the meter to the post that you disconnected the wire from, touch the other end of the wrapped wire to the wire that you disconnected from the valve. The meter should read some amperage if the power is going through the valve.

Let me know if this works.

Thanks for your response yes I got some voltage however I am not posititive how much voltage would be correct for proper functiioning of the thermopiles though . Possibly it would give me some voltage and the question is does that work for the two functions or just one function . Anyway thanks again.

Most thermopiles run off 750 millivolts.

And the amp meter would check a complete system for you, it is to show if you unit is overloading the heat anticipator of a thermostat.