Modulator Polarity on Ravenheat CSI85AT combination boiler.

[SueBeebies]

I had a problem recently and had to disconnect the gas valve. The boiler is now working. However both the leads to the modulator valve are the same colour although on testing they are DC. The voltage across the leads rises to about 9v once the boiler gets going but I can't see any difference to the flame whichever way round I connect them.

I can obviously tell which lead is positive and which is negative. Does any one know which way round they go on the gas valve or if it matters.

Many thanks,

Sue.

 

[Agile]

In theory it does not matter.

But sometimes the solenoid plumger gets a little magnetised so the gas flow may be a little different whichever way round its connected.

They use the same colour leads because its not important.

Tony

 

[megawatt]

But sometimes the solenoid plumger gets a little magnetised so the gas flow may be a little different whichever way round its connected.

You do have a habit of posting things I feel compelled to question Tony

Any further explanation of how this works would be fascinating?

 

[Agile]

If I dont answer then I get criticised but if I do answer that can also be the case as few installers have much understanding of electronics or physics.

I would have thought that you would understand the situation though!

For others I will endeavour to explain but it has little relevance to the OP.

If you subject ferrous materials to a magnetic field, according to their properties they can retain some magnetic field and become a permanent magnet.

Of course the material used for a solenoid plunger is designed to minimise the remanence. But they can retain some and if that happens they will aid or repel the field of the solenoid thus creating a slightly different gas pressure according to the polarity of the coil connections.

In practice the hysteresis of the plunger movement is usually much more significant. I have encountered hysteresis of as much as 2 mB on some gas valves which made setting up the valve quite tricky.

Tony

 

[megawatt]

Thanks for the explanation ... Much appreciated

 

[SueBeebies]

Thanks Tony. I also appreciated the extended answers you gave.

Sue