viessman 100-w

[ej-ay]

Hi Guys hope y'll got something to talk about now the olympics is here kool opening ceremony wasn't it, but that's not why i am here... why am i here went to do a gas cert in these prop, and discovered the boiler wouldn't fire upon any demand and soon went about showing me a fault code F5...there was no MI and i havent worked on any viessman so i rang up techincal department the next day and they told me theres a flap connected to the fan and it does stick but need to take out the burner i did and unstick it and reassemble it...and i did took out the burner and the flap wasn't sticking put everything back together and another fault code came up F4...mind you the only thing not working up until now is the igniter its not firing, but there was some suspiciously looking black powder around the electrode the one that has the ceramic coating and goes into the burner, so is that the fault before deciding to put in a new one and do i change the whole spark genereator or just the red lead with the electrode...babble on for a minute there:banghead::furious3::59:

Thanks to all patient and helpful contributors

 

[phpaul]

a few problems with these the flaps stick causing the f5 issue requiring a full strip down .
the boilers have a few weakness first the set screws that hold the burner door can strip the threads in the soft ali heat ex side plates.
f4 fault code could be no gas or no spark .if the spark gen is black or red one is the old one that can packup also the spark probe can packup as can the pcb also be-sure all wires are replaced correctly

 

[M77]

Power at gas valve??