Worcester Greenstar 24i Junior

[spike.gb]

Have just replaced fan as 240v across purple and brown but fan was not running. New fan runs for 5 seconds then goes to red flashing reset and blue slow flash 3/4 seconds on 1 second off. This is without built in programmer calling. Any help appreciated could PCB be at fault as well?

 

[kb76]

Any sign of moisture/damp getting in through flue? Check primary sensor resistance on top of heat exchanger. Also continuity across flue duct stat, if showing any signs of rust it could be knacked. Have had a couple of fans take the board with it but check sensors and stats first

 

[spike.gb]

Checked continuity through stats, no moisture. What resistance should I expect from the thermistor?

 

[kb76]

About 10k at room temp, hot water sensor same. Can usually see if it's got damp, they're pretty reliable but had couple when water got in through flue and shorted it out. Is it firing up for 5 secs or fan just runs then lock out?

 

[spike.gb]

Yes fan comes on at near max rate for 5 seconds goes to reset then fan carries on running at low speed.

 

[kb76]

If it's firing, check condense clear, flue and electrodes

 

[spike.gb]

It's not igniting just fan running before going to reset.

 

[ShaunCorbs]

ap switch maybe