Saunier Duval Xeon 60FF boiler won't run. Fan Hunting?

[Jboy]

Sorry, pc not near boiler! Just checked old & new APS both switch okay when I blow down H. Checked for 240V on NO terminal, no volts so APS not switching? No blockages on pipes, no leaks, fan blowing like a good 'un. ........

 

[Jboy]

Juat changed fan again (Luckily they sent a spare years ago when original started to hum, Fan lovely & clean & new looking) no change. I can hear the APS clicking & can see the voltmeter needle flicker on NO terminal of APS. It seems as though not enough air coming down red tube to switch it. But having said that shouldn't the boiler fire when I blow down the tube & definately switch it?

 

[gas4you]

Are you saying that you are trying it with the combustion cover/case on or off?

If it works with case off then it will be a fan venturi blockage. If not we'll have to keep thinking

 

[Rob]

What happens when you disconnect the N/O lead from the APS? Does the fan still cycle on off?

 

[nortimax]

Did you rewire the new APS correctly?

 

[Jboy]

Front cover is off. The 240v seems to disappear from terminal C on APS when APS clicks..... Almost like when it switches over to terminal NO something turns off the feed to C.....

 

[Jboy]

When NO disconnected fan still cycles on/off. APS looks okay with diag Red to C, Yellow-NC, Black to NO. I also took note when I removed old one.

 

[Jboy]

Thanks for the advise, looks like I might have to bite the bullet & "get a man in". Going for some hot soup now, finding it hard to type. If anyone else has any idea's, I'd be grateful.

 

[kevplumb]

try running the fan off a flying lead and see what happens then

 

[Jboy]

I think you're on the right track. With a flying lead on the fan the 3rd & 4th leds came on & boiler fired up!

 

[gasgeezer]

Check if pilot is on permant if it is cut power boiler will light turn down stat boiler will not light because pilot stays on if this is the case new gas valve will solve prob

 

[Jboy]

Check if pilot is on permant if it is cut power boiler will light turn down stat boiler will not light because pilot stays on if this is the case new gas valve will solve prob

Do you mean the pilot light itself? There isn't a permanent pilot. Normally the fan starts & then you hear the starter clicking & the pilot lights, then the main jet comes on.

 

[gasgeezer]

Yes if the pilot stays on after a demand has finished, the boiler will not relight the burner.But if you cut the power or gas and then reinstate it the boiler will light. its caused by the gas valve not extinguishing the pilot so the next demand it will not light burner because it thinks it is already alight

 

[Rob]

Where did you get the PCB from?

 

[Jboy]

PCB from a pukka central heating parts place.