Ferroli 77F Popular

[fleabo]

I have a 77FF Popular combi. The pilot light went out and can't be relit. Following the instructions, the fan runs and after 20s, the electrodes will fire when the ignition button is engaged, the pilot will then ignite. However, after sufficient time has elapsed (at least 15s) and the ignition button disengaged the pilot goes out. That is, the pilot ignites but does not hold.

The Thermocouple gives a rising voltage as heat is applied - around 14mv.

The cut-out thermostat reads zero ohms between its contacts.

The fault finding chart says that if the thermocouple and cut-out check OK then the problem is the gas valve.

Have I missed anything else that could be causing this problem?

Thanks.

 

[fleabo]

Is it possible to test the function of the gas valve in anyway?

 

[BingoBongo]

there is a way of bypassing the stat and fitting the t`couple to the gas valve but i wouldnt recomend incase you left it like that.

call in the gas man

 

[fleabo]

I said the thermcouple checked out OK. What I should have said is that I tested against an open flame and got a no-load voltage of 14mV.

When I put the thermocouple back in circuit in the boiler I get no volts from the thermocouple when the pilot is ignited. Also, the thermocouple's internal resistance is over 10kOhms. So not very much current even if it is shorted. But maybe the gas valve solenoid is typically a very high-resistance?

Any pointers gratefully received.

Thanks

 

[tonybhoy]

Personally I would just buy a thermocouple and try it cause they are relatively in-expensive and you boiler is relatively old so nothing ventured and all that however pretty sure your looking for 28/30 MV on a heated thermocouple and 14 MV or so on a cold one.

 

[fleabo]

Thanks for that - I get bo diddley at room temperature.