Potterton F not performing after a 3 port change over

I have today changed my 3 port valve on this system and followed the rules for draining down and up etc.

The valve I changed was to replace a landis and gyr obsolete model with the hortsmann from screwfix.com

Anyway replacing wire for wire (except earth as this new one is double insulated and does not require it), I fire up the system to find after fill tanks that the motrised pump is whirring around the water but the boiler is not responding to thermostat demand etc. It has not fired since draining down.

Note I waited for the tanks to fill. Bleeded all the radiators twice. And have cold water from both hot and cold taps all over the house.
I know the 3 port valve responds and sometime it changes over to ports A & B when I fiddle with the other gate valves in the airing cupoard.

No boiler flame from my trustie potterton F (I do not have a pressure gauge as I don’t think I need one on this type of system).

Any ideas to get my flame going?

check the wiring

IN addition to my previous post I have now checked the wiring and took before and after piccys and just unscrewed and screw the wires back intot he terminal blocks... same symptom, motor running not spark at boiler (note the terminal block I touched was connecting the cyclinder stat, motor and 3 port valve. BEFORE AND AFTER WIRING PICCYS below



PREVIOUS POST:
I have today change my 3 port valve on this system and followed the rules for draining down and up etc.

The valve I changed was to replace a landis and gyr obsolete model with the hortsmann from screwfix.com

Anyway replacing wire for wire (except earth as this new one is double insulated and does not require it), I fire up the system to find after fill tanks that the motrised pump is whirring around the water but the boiler is not responding to thermostat demand etc. It has not fired since draining down.



Note I waited for the tanks to fill. Bleeded all the radiators twice. And have cold water from both hot and cold taps all over the house.

No boiler flame from my trustie potterton F (I do not have a pressure gauge as I don’t think I need one on this type of system).

check you have a live feed to the boiler

Hey all is working, I put this picture and explanation here for all to see for a few weeks.
Sneakly there was a button underneath the boiler which I pushed like a child puts bananas into VCRs. And hey presto - BLUE FLAME in Window. To help indentify what this looks like on a Potterton F see below.



Thanks for all your help and keep up the good forum.

Ravi

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Potterton "F"? I think it's a Profile or similar.